Technical field [0001] 　The present invention relates to processing-induced transformation type composite structure steel sheet and a manufacturing method thereof, particularly, high strength working induced transformation type composite structure steel sheet excellent in surface properties and hole expansion, and a method for producing the same. BACKGROUND [0002] 　Recently, various lighter components of the motor vehicle for the purpose of improving fuel economy of automobiles has been advanced. Means weight varies by required performance parts each, for example, thinning by high strength of steel sheet in skeletal part, the panel part replacement, etc. of the light metal such as Al alloy steel has been performed. However, when compared to steel, since light metals such as Al alloys are expensive, the application destination at present, are limited primarily to luxury cars. On the other hand, demand for automobiles has shifted from developed countries to emerging economies, it is expected that in the future be required to achieve both light weight and low cost. Therefore, demand for weight reduction is increased by the high strength and thinning of the steel regardless of parts. [0003] 　Further, the passenger car wheel out of automobile parts, conventionally, the design of the aluminum casting from the viewpoint and forgings have been used often. However, recently the product having the same design of the aluminum wheel by devising the material and method of construction also made of pressed steel products have emerged. Aluminum wheels and similar design properties and aesthetic properties in order to realize steel wheel, in addition to excellent fatigue resistance and corrosion resistance, design properties and aesthetic properties obtained in the wheel disc, especially visible to the end user. Therefore, also in the steel plate (steel wheel disc) used in the wheel disc, high strength to achieve thinner, in addition to improved fatigue resistance and corrosion resistance, improved workability, design property as part and improvement of surface properties in order to improve the aesthetic properties has come to be demanded. [0004] 　In the molding process of the wheel disc, the processing of the hat portion is particularly severe. Moreover, what is managed in the most stringent standards in member properties of the wheel is the fatigue durability. Therefore, conventionally, as the characteristics required for the steel sheet for the wheel disc, Bay processability, drawability and fatigue resistance has been particularly important. Especially for fatigue resistance, when a load repeatedly during actual running is added when it is onboard in wheel geometry, stress concentration caused by the applied load mode and load application direction such hat portion back and vent It occurs at the site. Therefore, the steel sheet for the wheel disc from the above reasons, the notch fatigue properties is the fatigue properties in the stress concentration under has been important. 　In general, the steel sheet for the wheel disc, the high strength of at least 540MPa is required, in recent years, further, there is also a demand for higher strength to more than 780 MPa. [0005] 　Conventionally, as a steel sheet for these wheel disc, with an emphasis on the fatigue durability of a member excellent in fatigue characteristics, a composite structure steel sheet having a composite structure consisting of ferrite and martensite (the so-called Dual Phase steel. Hereinafter, "DP steel referred to as ".) has been used. [0006] 　Non-Patent Document 1, by a composite structure of such organizations (microstructure) DP steel composed of ferrite and martensite of the steel sheet, uniform elongation in the same strength is disclosed to be improved. [0007] 　As described above, in the DP steel, that can improve the strength and elongation is disclosed. However, the DP steel, bend formability, hole expansion, local deformability represented by burring workability, it is known low. Since this has a large intensity difference between the ferrite and martensite in the tissue, large strain and stress in the ferrite of the martensite near the time of molding is concentrated, it is why cracks may occur. [0008] 　Based on the above findings, obtained by reducing the intensity difference between the tissues, the high-strength steel sheet having excellent hole expansion has been proposed. For example, Patent Document 1, tissue that predominantly bainite or bainitic ferrite, while ensuring the strength, steel sheet greatly improved hole expansion has been proposed. The technique of Patent Document 1, by a substantially bainite or bainitic ferrite single tissue tissue, suppress the strain and stress concentration caused by the hardness difference as described above, of obtaining an excellent hole expansion it is a technique. [0009] 　However, high-strength steel sheet described in Patent Document 1, since the single tissue bainite or bainitic ferrite, although excellent in hole expansion, assuming the application to the wheel disk or the like, sufficient elongation not be obtained. [0010] 　In order to solve such a problem, for example, Patent Documents 2 to 4, tissue ferrite single tissue excellent elongation, Ti, high-strength steel sheet which attained high strength by precipitation strengthening of carbides such as Mo proposed It is. [0011] 　However, the steel sheet disclosed in Patent Document 2 needs to contain a large amount of Mo, the steel sheet disclosed in Patent Document 3 needs to contain a large amount of Ti, Mo, V. Therefore, in Patent Documents 2 and 3 technology, there is a problem that the alloy cost increases. Further, the disclosed steel sheet in Patent Document 4, after which it is necessary to contain a large amount and V, it is necessary to cool the middle of rolling for grain refinement. Therefore, there is a problem in terms of manufacturing cost. 　Also in these steel sheets, while indicating high elongation compared to a single structure steel of bainite and bainitic ferrite, elongation is degraded by was greatly strengthening the ferrite itself. Therefore, it is not compatible with the elongation and hole expansion at a high level. [0012] 　Patent Document 5, to produce a bainite instead of martensite in DP steel, has a small intensity difference between tissues by a composite structure of ferrite and bainite, is proposed DP steel having excellent hole expansion ing. [0013] 　However, the disclosed in Patent Document 5 techniques, in order to secure the strength by a small bainite contribution to improving the strength than the martensite, it is necessary to increase the area ratio of bainite structure. A high area fraction of bainite, the elongation is deteriorated and can not achieve both the elongation and hole expansion at a high level. [0014] 　Furthermore, steel sheets with reduced strength difference between the tissue and the hard tissue has been proposed by precipitation strengthening the ferrite DP steel in Patent Documents 6-8. [0015] 　However, in the technique described in Patent Documents 6-8 have become content of Mo is essential, there is a problem that manufacturing cost becomes high. Furthermore, even if precipitation strengthening of ferrite, the strength difference between the martensite is hard tissue is large, it can not be obtained sufficient hole expansion. [0016] 　By the tensile strength in Patent Document 9 controls the martensite fraction in 3-10% In the above DP steel 780 MPa, the steel sheet having improved elongation and hole expansion has been proposed. [0017] 　As shown in Patent Document 9, the DP steel case of the microstructure and the composite structure of ferrite and martensite, are often a large amount of Si for the purpose of promoting ferrite transformation is contained. However, the DP steel large amount is contained Si, scale pattern tiger stripes called red scale (Si scale) is formed on the surface of the steel sheet. Therefore, the steel sheet containing a large amount of Si, the application is difficult to high design wheel disc aesthetic resistance is required. [0018] 　The steel sheet described in Patent Document 9, although excellent elongation and hole expansion is obtained, since Si is contained more than 0.5%, it is difficult around the aforementioned Si scale pattern problems. Therefore, difficult to apply to various steel sheets used in high design wheel disc aesthetic resistance is required. [0019] 　To solve this problem, for example, Patent Documents 10 and 11, suppressing the occurrence of red scale by suppressing the content of Si to 0.3% or less, further refining the precipitates by adding Mo technique to obtain a high tensile strength hot-rolled steel sheet is disclosed which has excellent stretch-flange formability yet high strength by. [0020] 　However, steel sheets disclosed in Patent Documents 10 and 11, since the essential inclusion of expensive Mo, cost increases. Further, in these inventions, a structure consisting essentially precipitation strengthened ferrite single phase, the elongation is not sufficient. Also, it does not also been studied for the fatigue characteristics notch. [0021] 　As a technique for improving the fatigue properties of the steel sheet having a composite structure, Patent Document 12, Si, Al, By including such a Mn a predetermined relationship, a technology for improving the low cycle fatigue characteristics are disclosed there. [0022] 　However, Patent Document 12, there is no technical disclosure on notched fatigue properties of fatigue properties in the stress concentration under. Further, in the Patent Document 12 technology, it is necessary to contain Si 0.6% or more, it is difficult to avoid the formation of Si scale pattern. [0023] 　Patent Document 13 and 14, Al and Si are contained in the composite, the processing-induced transformation type composite structure steel sheet having excellent ductility than DP steel by a microstructure containing retained austenite (hereinafter, the "TRIP steels" notation is.) producing techniques have been disclosed. Further, in the steel sheet of Patent Document 13 and 14, it is also improved hole expansion by the main phase of polygonal ferrite. [0024] 　However, Patent Document 13 and 14, there is no technical disclosure on notched fatigue properties of fatigue properties in the stress concentration under. Moreover, such a TRIP steel, assuming the application to steel wheels, required during the processing of the hub hole and vent the wheel, there is a problem of low local deformability such as hole expansion. CITATION Patent Document [0025] Patent Document 1: Japanese Patent 2003-193190 JP Patent Document 2: Japanese Patent 2003-089848 JP Patent Document 3: Japanese Patent 2007-063668 JP Patent Document 4: Japanese Patent 2004-143518 JP Patent Document 5: Japanese Patent 2004-204326 JP Patent Document 6: Japanese Patent 2003-321737 JP Patent Document 7: Japanese Patent 2003-321738 JP Patent Document 8: Japanese Patent 2003 -321739 JP Patent Document 9: Japanese Patent 2011-184788 JP Patent Document 10: Japanese Patent 2002-322540 JP Patent Document 11: Japanese Patent 2002-322541 JP Patent Document 12: Japanese Patent open 2010-150581 JP Patent Document 13: Japanese Patent Laid-open 5-112846 discloses Patent Document 14: Japanese Patent 2002-25 6389 JP Non-patent literature [0026] Non-Patent Document 1:. Matsumura et al, Trans ISIJ, vol 27 (1987), p 570.. Summary of the Invention Problems that the Invention is to Solve [0027] 　TRIP steels are steel obtained by dispersing and residual austenite and bainite during soft ferrite has a very high uniform elongation, yet high strength. However, between the ferrite or bainite and residual austenite, or retained austenite and ferrite or bainite is between the working induced transformation to the resulting martensite, the difference in intensity is present. Therefore, at the time of deformation, the above strain and stress concentration due to the intensity difference is adapted to generate the interface of the crystal. The voids cause ductile fracture generation, it becomes easy to grow, local deformability of TRIP steel involved in hole expansion is very low. [0028] 　On the other hand, in-out key notch fatigue properties in evaluating the fatigue property of stress concentration under Unlike normal fatigue properties to fatigue crack initiation in rupture life the majority, the majority of the rupture life It has been known to be affected by the propagation of fatigue cracks. TRIP steels have a ferrite soft, and residual austenite and bainite were dispersed in ferrite. The TRIP steel having such a structure, the fatigue crack soft ferrite preferentially propagate relatively hard retained austenite or retained austenite working induced transformation to hard martensite caused by fatigue crack propagation since decreasing the propagation velocity becomes failure, the notch fatigue characteristics are considered to be high. [0029] 　However, the fraction of retained austenite, and tissue TRIP steel such as size, and the propagation velocity of void formation and growth behavior causes ductile fracture and fatigue cracks, related detailed study has not been conducted so far. Therefore, to improve the local deformability, such as hole expansion and deformation-induced transformation type composite structure steel sheet (TRIP steel) with reduced propagation velocity of the fatigue crack has not yet been provided. [0030] 　Furthermore, aluminum wheels equivalent design properties, in terms of the aesthetic properties to avoid the formation of Si scale pattern to be realized in steel wheels, excellent strength elongation balance, corrosion resistance, to any of the hole expansion properties and notch fatigue not yet been provided also for the steel plate. [0031] 　The present invention was made in view of the above problems. The present invention has a tensile strength of at least 540 MPa, at the same time strength elongation balance (TS × El), hole expansion, excellent corrosion resistance and notch fatigue characteristics, further excellent in surface properties, high strength strain-induced transformation composite and to provide a steel sheet and a manufacturing method thereof. Means for Solving the Problems [0032] 　The present inventors, to avoid the formation of Si scale pattern, excellent in order to obtain surface properties and corrosion resistance, TRIP steel having a steel component with a limited Si content (chemical composition) (strain-induced transformation type composite structure the steel plate) on the assumption, the components and structure of TRIP steel, strength, elongation, an extensive study about the relationship between the hole expansion and notched fatigue properties was carried out. As a result, the steel component (chemical composition), and the dispersion state of the residual austenite, the strength by controlling the shape and size, elongation, and found a technique for improving the hole expansion and notched fatigue properties. [0033] 　Specifically, by containing Al in proper quantity as a substitute for Si used as ferrite formers (ferrite transformation promotion element) in general TRIP steels, after avoiding the formation of Si scale patterns, polygonal ferrite composite organized to promote to the residual austenite and bainite as the main phase the second phase a further fraction of retained austenite, by controlling such an optimum range in size, elongation,-out expansibility and cutout fatigue It was found that it is possible to improve the characteristics. 　In addition to the steel ingredients, by devising a method of hot rolling, it revealed that these optimum material is obtained with good reproducibility. [0034] 　The present invention was made based on the above findings. Its gist is as follows. (1) processing-induced transformation type composite structure steel sheet according to one embodiment of the present invention, the chemical composition, in mass%, C: 0.075% than 0.150% or less, Si: 0.50% or less, Mn: 0.20 ~ 3.00%, P: 0.010 % or less, S: 0.005% or less, Al: 0.040 ~ 1.500%, N: 0.0100% or less, Ti: 0.015 ~ 0.200%, Nb: 0 ~ 0.060 %, Cu: 0 ~ 1.20%, Ni: 0 ~ 0.60%, Mo: 0 ~ 1.00%, V: 0 ~ 0.200%, Cr: 0 ~ 2.00%, W : 0 ~ 0.50%, Mg: 0 ~ 0.0100%, Ca: 0 ~ 0.0100%, REM: 0 ~ 0.100%, B: 0 ~ 0 .0020%, the balance: a Fe and impurities, and satisfies the following formula (i); tissue in 1/4 thickness of the plate thickness, an area ratio of 50% to 85% of Po Filled with Rigo ferrite, and 3-10% of residual austenite, 5 to 47% of bainite, and a less than 1% of the fresh martensite and tempered martensite in total, and the following (ii) expression, the in tissue, precipitates containing TiC is, 1 × 10 16 atoms / cm 3 is contained more, the average particle size of the residual austenite is 1.0 ~ 5.0 .mu.m in equivalent circle diameter, recent of said residual austenite the average value of the contact distances are 3.0 ~ 10.0 [mu] m, the average diameter of the precipitates is 3nm or less. -48 × Ti (N / 14 + S / 32) ≧ 0 (i) 0.01 　is C to produce a residual austenite, an element which contributes to the improvement of the transformation induced plasticity by strength elongation balance (TS × El). Further, C is an element which contributes to improvement of strength by precipitation strengthening by forming a Ti and precipitates. Therefore, C is an important element. C content can not be obtained strength of at least 540MPa in the following 0.075%. Also, C content is less 0.075% can not be obtained the effect of improving the ductility (elongation) caused by the residual austenite ensured. On the other hand, the area ratio of residual austenite and C content exceeds 0.150% of decrease is 10% ultra next hole expansion. Therefore, C content is at most 0.075% greater than 0.150%. [0048] Si is one of the important elements in the present embodiment. Si is both a deoxidizing element, is an element to increase the temperature range of two-phase region with by enlarging the ferrite region temperature to the high temperature side ferrite and austenite with the increase of the content. Therefore, in order to obtain a strain-induced transformation type composite structure steel is originally it is desirable to include Si. [0049] 　However, Si is markedly generate Si scale pattern like tiger stripes on the surface of the steel sheet to deteriorate significantly the surface properties. Further, Si may decrease extremely the productivity of the descaling process (pickling and the like) in the finishing line line. When Si content exceeds 0.50%, significantly surface properties deteriorate, it is extremely deteriorated productivity of the pickling process. Also, it is carried out any descaling method, chemical conversion treatability deteriorates, corrosion resistance after painting is lowered. Therefore, the Si content is set to 0.50% or less. Si To scale patterns not cause is desirably a Si content is 0.10% or less, and more desirably to 0.07% or less, further desirably 0.05% or less. [0050] 　Meanwhile, Si is an element that has the effect of suppressing scales, the generation of scale-based defects such as spindle scale. Although the above effect, Si content is obtained when 0.02% or more. Therefore, the lower limit of the Si content may be 0.02%. [0051] Mn is an element contributing to the strengthening of the ferrite. Further, Mn is also an element to expand the temperature range of two-phase region of the increase with the austenite region temperature was allowed to expand to a low temperature side ferrite and austenite content thereof. If the temperature range of two-phase region is enlarged, tends to occur phase separation of ferrite and austenite during after finish rolling cooled, it is advantageous for obtaining a strain-induced transformation type composite structure steel. To obtain the above effect, the Mn content is set to 0.20% or more. On the other hand, Mn content slab cracking occurs significantly during casting exceeds 3.00%. Therefore, the amount of Mn is less 3.00%. [0052] 　Further, Mn, and too high hardenability when the content exceeds 2.50%, a long air retention for precipitating ferrite during after finish rolling cooled in order to obtain the desired tissue It must be performed occurs, and productivity may be lowered. Therefore the Mn content is 2.50% or less is desirable, or less and more preferably 2.20%. 　Meanwhile, in order to suppress the occurrence of hot cracking due to S are, Mn content and S content and it is desirable to satisfy the Mn / S ≧ 20. Each element symbol in the formulas represents the content of each element contained in the steel (mass%). [0053] 　P is an impurity element. P content segregation becomes conspicuous on the crystal grain boundaries exceeds 0.010%. In this case, it is promoted the grain boundary embrittlement, notched fatigue properties local ductility is deteriorated is reduced. The embrittlement of the weld zone becomes remarkable. Therefore, the P content to 0.010% or less. P content it is desirable small, the lower limit of the P content is not particularly defined. However, making the P content less than 0.0001%, so the manufacturing cost is significantly increased economically disadvantageous, the P content may be 0.0001% or more. [0054] 　S is an impurity element. S is weldability adversely affects the productivity of the casting and during hot rolling. Further, S is, forms coarse MnS in the steel sheet, reduce the hole expansion. Since the S content exceeds 0.005% its effect becomes remarkable, the S content to 0.005% or less. S content it is desirable small, the lower limit of the S content is not particularly defined. However, the S content be less than 0.0001%, because it is economically disadvantageous, the S content may be 0.0001% or more. [0055] Al is both a deoxidizing element, as with Si, and the content of the ferrite zone temperature was increased to the high temperature side ferrite and austenite with increasing it is an element to increase the temperature range of two-phase region. Therefore, Al is one of the important elements in the present embodiment. To obtain this effect, the Al content is 0.040% or more. On the other hand, Al content, it is difficult to exceed 1.500%, the ferrite region temperature is completed finish rolling at austenite region too enlarged to the high temperature side. In this case, deformed ferrite in the steel sheet as a product remains ductility and hole expansion is deteriorated. Further, when the Al content exceeds 1.500% Contact it also made tundish nozzle is easily clogged during casting. Therefore, the Al content to less 1.500%. However, Al content exceeds 1.000%, the non-metallic inclusions is increased, such as alumina, because it may local ductility deteriorates, Al content is preferably not more than 1.000%. [0056] 　N is an impurity which inevitably mixed during refining of the steel. Further, N represents an element that Ti, combined with Nb or the like to form nitrides. When N content exceeds 0.0100% nitrides, a relatively high temperature tends to coarsely precipitate, there is a possibility that coarse nitrides as a starting point of cracking during burring. Accordingly, the content of N to 0.0100% or less. Further, N is, Ti, to form a Nb and nitride, Nb described later, the effect of Ti is reduced. Therefore, Ti, N content in order to make effective use of Nb is small is desirable. 　Aging degradation the N content exceeds 0.0060% becomes severe. Therefore, in case of suppressing the aging degradation, it is desirable that the N content is 0.0060% or less. Further, after standing at room temperature more than two weeks after manufacture, when applying the steel sheet according to the present embodiment with respect to members that assumes be subjected to machining, N content, from the viewpoint of aging deterioration measures 0.0050 % and more preferably less than or equal to. Also, standing under summer high temperature environment, or in consideration of the use in environments involving export by ship or the like to the low latitudes, N content is more preferably less than 0.0040%. [0057] Ti is an important element in advance steel sheet according to the present embodiment. Ti is precipitated as TiN in austenite region during the hot rolling, in addition to contributing to the refinement of austenite grain size, the remaining Ti simultaneously ferrite transformation proceeds during cooling after hot rolling finished TiC etc. finely precipitated as carbide. Strength is improved by carbides such as austenite grain size refinement and TiC by TiN precipitation is precipitation strengthened ferrite grains. In order to obtain these effects, it is necessary to set the Ti content of 0.015% or more. On the other hand, not only the Ti content is effective even exceed 0.200 percent saturated, also reduces the solid solution C by Ti carbide or Ti carbosulfide is precipitated in the austenite region, the desired metal after transformation it becomes difficult to obtain the organization. Therefore, the Ti content is 0.200% or less. Moreover, if the Ti content exceeds 0.150%, the tundish nozzle is easily clogged during casting. Therefore, the Ti content is desirably 0.150% or less. [0058] 　Further, in order to obtain the above-mentioned effects, Ti content, in relation to the N content and S content, it is necessary to satisfy the following formula (i). Ti-48 × (N / 14 + S / 32) ≧ 0 (i) 　the formula (i) is less than 0, since the Ti to be precipitated as TiC no longer present, precipitation strengthening can not be obtained. 　Each element symbol in the formulas represents the content of each element contained in the steel (mass%). [0059] 　Steel sheet according to the present embodiment contains the above chemical components, and the balance basically that the Fe and impurities. However, further, in order to enhance the strength and hole expansion, instead of a part of Fe, the extent shown below containing Nb, Cu, Ni, Mo, V, Cr, one or more selected from W it may be. However, since these elements do not necessarily have to be contained, the lower limit is 0%. Here, the "impurities", in manufacturing the steel industrially, ores, raw material scraps, a component mixed by various factors of the manufacturing process, is allowed to the extent that the present invention does not adversely affect means shall. [0060] Nb, Cu, Ni, Mo, V, Cr and W, the effect of improving the strength of the steel sheet by precipitation strengthening or solid solution strengthening is an element having. Therefore, it may be contained if necessary one or more selected from these elements. To obtain the above effect, Nb: 0.005 ~ 0.060%, Cu: 0.02 ~ 1.20%, Ni: 0.01 ~ 0.60%, Mo: 0.01 ~ 1. 00%, V: 0.01 ~ 0.200 %, Cr: 0.01 ~ 2.00% , and W: it is preferable that its content be at least one selected from 0.01 to 0.50%. 　On the other hand, the effect can be excessively by containing these elements is saturated, it is uneconomical. Therefore, even if to be contained, the Nb content 0.060% or less, a Cu content of 1.20% or less, a Ni content of 0.60% or less, the Mo content of 1.00% or less, V content 0.200% or less, the Cr content of 2.00% or less, the W content is set to 0.50% or less. [0061] Mg, Ca and REM (rare earth elements) are ductility and hole become starting points of fracture controlling the morphology of nonmetallic inclusions causing degradation of expansibility, it is an element that improves the workability of the steel sheet. Therefore, it may be contained if necessary one or more selected from these elements. To obtain the above effect, Mg: 0.0005 ~ 0.0100%, Ca: 0.0005 ~ 0.0100% , and REM: containing one or more selected from 0.0005 to 0.100% the cause is desirable. On the other hand, even if excessively by containing these elements, the effect is reduced economic efficiency saturated. Therefore, even if to be contained, the Mg content of 0.0100% or less, a Ca content of 0.0100% or less, the REM content is 0.100% or less. The REM, means 17 elements combined Y and Sc to 15 lanthanoid elements, REM content means the total amount of these elements. [0062] 　B increases the hardenability of steel, which is an element having an effect of increasing the structural fraction of the retained austenite. To obtain this effect, B content may be used as 0.0002% or more. More preferably, it is 0.0010% or more. On the other hand, when the B content is excessive, the effect is reduced economic efficiency saturated. Therefore, even if to be contained, B content and to 0.0020%. Further, B is an element responsible for causing the slab cracking in after continuous casting cooling process, from this point of view it is desirable that the B content is 0.0015% or less. [0063] 　Steel sheet according to the invention according to the present embodiment is not intended to detract from Zr as the impurity element, Sn, Co, also contain 1.0% or less in total of Zn its effect. However, since flaws during high content to the hot rolling of Sn may occur, the Sn content desirably 0.05% or less. [0064] 2. Microstructure 　will be described organization of the steel sheet according to the present embodiment (microstructure). Organization of the steel sheet according to the present embodiment, representative tissue is considered to be obtained, a tissue position in the plate thickness 1/4 thickness (1/4 of the position of the sheet thickness in the sheet thickness direction from the surface). [0065] 0.01 　polygonal ferrite is an important organization in ensuring elongation. Among ferrite, than high bainitic ferrite dislocation density, towards the polygonal ferrite dislocation density has excellent ductility low, contributing to improvement of elongation. Therefore, in order to obtain excellent stretch, the area ratio of polygonal ferrite is 50% or more. On the other hand, when the polygonal ferrite is 85%, it is difficult to ensure the strength. Therefore, the area ratio of polygonal ferrite to 85% or less. 　Polygonal ferrite produced by diffusion mechanism does not have an internal structure in the grains, and the grain boundary is a straight line or arc. On the other hand, bainitic ferrite or bainite has an internal structure, and a grain boundary shape Ashukyura have distinctly different tissues and polygonal ferrite. Therefore, the polygonal ferrite, and bainite or bainitic ferrite, a structure photograph obtained by using an optical microscope after etching by nital, can be determined by the presence or absence of grain boundary shape and internal structure. The internal structure is not clearly appear, and the grain boundary shape Ashukyura - if shape structure (quasi polygonal ferrite) is present counts as bainitic ferrite. 　Incidentally, like the case where the temperature of hot rolling is too low, there is a case for receiving the rolling after the ferrite was produced. Ferrite receiving such processing as deformed ferrite, distinguish polygonal ferrite. Deformed ferrite, the grain boundary shape is linear, and therefore has a shape extending in the rolling direction by rolling, discrimination between other tissues, such as polygonal ferrite is possible. Or without internal structure in this embodiment, counting when the grain boundary shape aspect ratio of linear and and maximum length in the rolling direction of the grain and a thickness direction of the maximum length of 4 or more as a deformed ferrite to. [0066] 　It retained austenite transformation induced plasticity: an important tissue for expressing excellent elongation by (TRIP TRansformation Induced Plasticity). When the area ratio of the dispersed retained austenite islands is less than 3%, it is difficult to ensure sufficient elongation. In addition, delay the effect of the propagation of the fatigue crack is lost. On the other hand, when the area ratio of residual austenite is more than 10% are considered to voids site, distance between the hard martensite each other produced by strain-induced transformation from the residual austenite is reduced, it becomes a void is easily connected. In this case, hole expansion tends lead to ductile fracture is deteriorated. Thus the area ratio of residual austenite of 3 to 10%. [0067] 　The steel sheet according to the present embodiment, from 5 to 47% of bainite area ratio. The bainite is less than 5%, enrichment of C into austenite becomes insufficient, securing of residual austenite becomes difficult. Therefore, the 5% limit of the area ratio of bainite. It is preferable from the viewpoint of 10% or more. On the other hand, when the bainite exceeds 47%, ductility is lowered. Therefore, the 47% upper limit of the area ratio of bainite. Area ratio of bainite is from the point of view is desirably 40% or less. 　The steel sheet according to the present embodiment, permits the inclusion of fresh martensite of less than 1% (M) and tempered martensite (tM) in total. Hole expansion with fresh martensite and tempered martensite is 1 percent in total is degraded. Martensite and tempered martensite, it may be 0%. 　Further, the steel sheet according to the present embodiment, polygonal ferrite, residual austenite, bainite, bainitic ferrite, in addition to the fresh martensite and tempered martensite, if 1% or less, further, other tissues (e.g., perlite also include deformed ferrite, etc.), it does not impair the effect. 　Here, the deformed ferrite, hot rolling temperature is Ar 3 when made in the following transformation point, the elongation in the rolling direction polygonal ferrite receiving rolling, and the dislocations introduced by the processing in the grains It refers to a condition that includes. 　In the present embodiment, the bainite is bainite (alpha B) containing no coarse carbides between lath. This carbon to austenite is discharged during bainite transformation, which is a characteristic microstructure when containing a sufficiently stable retained austenite at room temperature. [0068] 　Each tissue can be determined as follows. That is, tissue fraction (area ratio) can be obtained by the following method. First, a sample collected from the hot-rolled steel sheet is etched with nital. To structure photograph obtained by viewing the 300 [mu] m × 300 [mu] m in a plate 1/4 depth position of the thickness using an optical microscope after etching, by performing image analysis, polygonal ferrite, the area ratio of the deformed ferrite and pearlite and obtaining the total area ratio of bainite and martensite. Then, using the Repera corroded samples, with respect to structure photograph obtained by viewing the 300 [mu] m × 300 [mu] m at the position of 1/4 depth of thickness with an optical microscope, by performing image analysis, residual austenite and martensite to calculate the total area ratio of the site. 　Furthermore, the rolling surface normal direction using samples scalping to 1/4 depth of plate thickness from the obtained volume fraction of retained austenite in the following manner by X-ray diffraction measurement. That is, simply obtain the volume fraction using the following (ix) from equation difference of the reflection surface strength between austenite and ferrite with Kα line of Mo. Vγ = (2/3) × {100 / (0.7 × α (211) / γ (220) +1)} + (1/3) × {100 / (0.78 × α (211) / γ ( 311) +1)} (ix) However, α (211), γ ( 220) and gamma (311) are each ferrite (alpha), an X-ray reflection surface strength of the austenite (gamma). 　The volume fraction of retained austenite are the equivalent to the area ratio, which is the area ratio of residual austenite. 　By this method, it is possible to obtain polygonal ferrite, deformed ferrite, bainite, martensite, residual austenite, the respective area ratios perlite. 　The volume fraction of residual austenite is because the value was almost identical using any of the methods of optical microscopy and X-ray diffraction method can be obtained, no problem by using any of the measurements. [0069] 　In contrast, in polygonal ferrite area ratio described above and, the area fraction of retained austenite 10 If% or less, in order to obtain a more 540MPa tensile strength should be strengthened by reinforcing tissue deposition. That is, it is necessary to polygonal ferrite is precipitation strengthening by Ti carbides. 　Further, if the component is constant, a relationship of approximately inversely correlated to the average diameter (circle equivalent diameter) and the density of the precipitates containing TiC. In the present embodiment, in order to obtain a strength increase of more than 100MPa tensile strength by precipitation strengthening, the mean diameter of the precipitates containing TiC and less 3nm equivalent circle diameter, and the density of 1 × 10 16 atoms / cm 3 and more. 　The average diameter of the precipitates containing TiC contribution to precipitation strengthening as a 3nm greater is insufficient. The number density of × 10 1 16 atoms / cm 3 , the effect as precipitation hardening is also less than insufficient. 　The average diameter of the precipitates containing TiC, number density can be measured by the following method. 　From the hot-rolled steel sheet, to prepare a needle-like sample by cutting and electropolishing method. At this time, we may utilize a focused ion beam processing method together with the electrolytic polishing method if necessary. This needle-shaped sample, the three-dimensional atom probe measurement method to obtain the three-dimensional distribution image of the composite carbonitride. [0070] 　According to the three-dimensional atom probe measurement, it is possible to reconstruct the accumulated data to obtain a three-dimensional distribution image of the actual atoms in real space. Precipitation in the measurement of the particle size of the precipitates containing TiC, comprising the constituting atoms and the lattice constant of the precipitate of the observation target, obtains the diameter when the precipitate was considered sphere, a determined diameter, the TiC It is defined as the particle size of the object. [0071] 　In the present embodiment, of the precipitates containing TiC, particle size counts those 3nm or less. Although not the lower limit of the particle size particularly limited, if it is less than 0.5 nm, since the grain size is smaller than the lattice constant of TiC, not considered to precipitate. Based on the number of precipitates containing measured TiC, number density (number / cm 3 Request). [0072] <0.01 　difference burring workability and hole expanding property has been proposed hole expanding test as a test method for briefly appear, the hole expansion value obtained in this study are widely used as an index for evaluating the local deformability ing. Generation occurrence and development of cracks in the hole expansion processing of void growth, linking caused by ductile fracture to elementary process. Large case of the intensity difference between microstructure as TRIP steel is relatively hard retained austenite or retained austenite high strain as due to strain induced transformation to the resulting hard martensite, the concentration of stress occurs. Therefore, in general, voids occur, easily grow, hole expansion value is low. However, the present inventors have found that by controlling the size of the residual austenite, the dispersion state, generation of voids, growth, coupled to delay, found that it is possible to improve the hole expanding property. [0073] 　Ductile fracture which is believed to be involved in hole expansion, the occurrence and growth subsequent voids is believed to be caused by the coupling. Also, generating sites of voids is believed to be a hard martensite generated by processing-induced transformation from the residual austenite. Therefore, if the island-like shape of the retained austenite, stress concentration is relaxed, generation of voids martensite after transformation is thought to be suppressed. The island not only show a state where the residual austenite is not linked to sequences in rows, which also include that the individual shape has a shape close to a small sphere of stress concentration points. Retained austenite, ferrite grains or bainite grain corner, it is desirable to have dispersed like islands in the edge and the grain boundary. [0074] 　The present inventors have met the following (ii) expression, by optimizing the state of dispersion of residual austenite, the hardness and the like, headline generation of voids, growth, that excellent hole expansion value by the delay of the connection is obtained It was. Further, development of fatigue cracks is reduced propagation velocity of the fatigue cracks by stopping or bypassed, it found that excellent notched fatigue strength. 0.01 　In the heating step, the slab obtained by casting or the like, is heated before hot rolling. The heating temperature is, as 1350 ° C. less than the minimum slab reheating temperature (SRTmin) ° C. or more, which is calculated based on the following (iv) expression is heated in a heating furnace. = 7000 SRTmin / {2.75-log 10 (Ti × C)} - 273 (iv) 　wherein each element symbol in the formulas represents the content of each element contained in the steel (mass%). [0083] 　Carbonitrides of heating temperature generated during the casting is less than SRTmin (° C.) Ti is not dissolved sufficiently in the matrix. In this case, not the fine precipitates as Ti carbides after the finish during rolling after completion of cooling or coiling, the strength improving effect utilizing precipitation strengthening can not be obtained. Therefore, the heating temperature in the heating step is set to SRTmin (° C.) or higher. Further, the heating temperature lower than 1100 ° C., for significantly impair the schedule on operational efficiency, the heating temperature is desirably more than 1100 ° C.. 　On the other hand, to the heating temperature and 1350 ° C. greater, as well as significantly impair the productivity, leads to coarsening of the austenite grain size, which causes a reduction in toughness and hole expansion. Therefore, the heating temperature is 1350 ° C. or less. [0084] 　Not particularly set for the heating time in the heating step. However, in order to sufficiently proceed the dissolution of the carbonitrides of Ti, it is desirable to retain more than 30min after reaching the heating temperature described above. In the case of sufficiently uniform heating in the thickness direction of the slab, it is desirable to retain more than 60min. On the other hand, heating time from the viewpoint of yield loss scale off, less desirably 240 min. However, when rolling the slab after casting and direct remain hot is not limited to this. [0085] 　After the heating step, to obtain a crude bar subjected to rough rolling without any particular waiting the heating furnace slab extracted from. In a temperature range of 950 ~ 1050 ° C. This rough rolling step (first temperature range), the reduction of the rolling reduction of 20% or more 1 or more passes. Is lower than the temperature of the rough rolling is 950 ° C., and increases the hot deformation resistance in the rough rolling, the operation of the rough rolling is likely to lead to failure. On the other hand, if the temperature of the rough rolling exceeds 1050 ° C., too grown secondary scale generated during the rough rolling, it may be difficult to remove the scale descaling or finish rolling carried out later. [0086] 　Furthermore, the rolling reduction in rough rolling in the temperature range Without at least one pass rolling of 20% or more, processing of austenite, and due to subsequent grain utilizing recrystallized grain refinement and solidification structure which elimination of anisotropy can not be expected. In this case, the form of the residual austenite is changed from the island-shaped into a film, the hole expansion properties are deteriorated. Particularly, when rolling the slab after casting and direct remain hot, cast structure remains, the change in the film-like form of the residual austenite may become noticeable. [0087] 　Rolling pass number in the rough rolling process, the processing and recrystallization austenite If it is multiple paths or two passes are repeated, since the finish rolling prior to the average austenite grain is comminuted to 100μm or less desirable. When performing the rolling or two passes, it can be stably to 5μm or less average grain size of retained austenite. However, it left effect a total reduction ratio of the plurality of paths is less than 60% can not be obtained sufficiently. On the other hand, the total rolling reduction not only its effect exceeded 90 percent saturated, inhibit productivity number of paths is increased, which may cause a temperature drop. The path number for the same reason 11 or less. The total reduction ratio, before the first pass inlet plate thickness with respect to the, the total reduction amount with respect to the reference (the difference between the exit thickness Metropolitan after the final pass in the first pass before the inlet plate thickness and rolling in the rolling) it is the percentage. The total rolling reduction, rough rolling, is calculated separately respectively finish rolling. That is, the total reduction ratio in the rough rolling is the percentage of the difference between the exit thickness Metropolitan after the final pass in the first inlet plate thickness of the pass before the rough rolling in rough rolling. [0088] 　performing finish rolling after the completion of the rough rolling step. Time from after the rough end of rolling to the start of the finish rolling is within 150s. Exceeds 150s, TiC which Ti of austenite in the rough bar is precipitated as a carbide of coarse TiC, when the ferrite transformation completion after at austenite / ferrite transformation or winding in the cooling step after precipitated in ferrite fine is reduced, the strength improvement effect due to precipitation strengthening can not be obtained sufficiently. Also, the mean particle diameter of austenite grains before finish rolling grain growth of austenite proceeds are coarsened beyond 100 [mu] m, there are cases where the average crystal grain size of the residual austenite is greater than 5 [mu] m. [0089] 　On the other hand, it is not necessary to limit the lower limit is particularly time after rough rolling termination to the start of the finish rolling, finish rolling start temperature unless used is less than 30s a special cooling device is not less than 1000 ° C. blister as a starting point, such as scales and spindle scale defect occurs between the surface scale of the steel sheet area iron finish rolling before and path. In this case, scale defects are easily generated. Therefore, the time from after the rough rolling termination to the start of the finish rolling is to the 30s or more. [0090] 　In the finish rolling step, and less than 1000 ° C. 930 ° C. or higher rolling start temperature (second temperature range). When the finish rolling start temperature is lower than 930 ° C., Ti in austenite by strain induced precipitation is precipitated as a carbide of coarse TiC. In this case, after the TiC to be precipitated in ferrite fine is reduced at the austenite / ferrite transformation during or ferrite transformation completion after winding during cooling, precipitation can not be sufficiently obtained intensity improvement effect by strengthening. On the other hand, if it is the finish rolling start temperature of 1000 ° C. or more, the scales between the surface scales of the steel sheet locations iron between before finish rolling and path, blister serving as a starting point for the spindle scale defects occur, scale defects generated it may become easier to. [0091] 　Finish rolling end temperature Ar 3 transformation point ~ Ar 3 and transformation point + 80 ° C. temperature range of (temperature range of the third). Finish rolling end temperature is Ar 3 is less than the transformation point, the residual austenite in the tissue of the finally obtained steel sheet is not a island, a dispersed state linked arrayed in rows. The average value of the minimum distance of the residual austenite is less than 3 [mu] m, the hole expansion properties are deteriorated. On the other hand, the finish rolling end temperature is Ar 3 is much controlled ferrite transformation even if suppressing the cooling pattern after rolling exceeds transformation point + 80 ° C., there is a possibility that the residual austenite is excessively formed. Further, the residual austenite is thermodynamically unstable, very early in the processing-induced transformation occurs in the deformed, there may not be obtained excellent elongation. [0092] 　The total reduction ratio in the finish rolling is 75 to 95%. When the total reduction ratio is less than 75%, can not be sufficiently fine austenite grains, it is impossible to make the average particle size of the residual austenite in the production version of the microstructure to 5μm or less. On the other hand, when the total reduction ratio exceeds 95%, the effect takes excessive load application to the rolling machine not only saturated, operational undesirable. [0093] 　Finish rolling is performed a rolling multiple passes (at least two passes). When performing finish rolling at a rolling multiple passes, rolling according to non-recrystallized and fine grains of austenite grains by repeating a plurality of times and recrystallization interpass time to the next pass, the stably retained austenite the average particle size can be set to 5μm or less. When performing a rolling multiple paths, it is preferable to use a tandem rolling mill. 　Further reduction ratio of each pass is desirably 10% or more. Especially in three passes of the finishing mill later stage in the rolling reduction is less than 10%, and the average reduction rate is less than 10%, significantly advanced grain growth after the end rolling passes and between the finish rolling, the average retained austenite there are cases where the particle size can not be stably 5μm or less. [0094] 　Not particularly limited rolling speed in the present embodiment. However, the rolling speed in the finishing final stand side becomes longer the time between the finish rolling pass is less than 400Mpm, austenite grains become coarse growth. In this case, it may become impossible to stably 5μm or less average grain size of retained austenite. Therefore rolling speed in the finishing rolling is preferably set to more than 400Mpm. Furthermore, it is possible to stably and 5μm or less average grain size of retained austenite to be 650Mpm, more desirable. Not particularly necessary to limit the upper limit of the rolling speed, but equipment constraints on 1800mpm less is practical. [0095] 　After the end of the final rolling, the steel sheet, optimizes cooling by controlling the runout table, wound. First, the time until the start of the first cooling after finish rolling completion is desirably set within 3s. In austenite before transformation and the time from the finish rolling end to the first cooling start more than 3s, fine and precipitate in ferrite during coarse and precipitation proceeds carbonitride non inconsistent Ti, after cooling precipitation amount of carbide containing inconsistent TiC is reduced, the strength is lowered. In addition, the growth coarsened austenite grains, it may become impossible to 5μm or less average grain size of retained austenite in the production version of the microstructure. Is not necessarily limited for the time limit from the end of the final rolling to the first cooling start, processed structure layered by rolling is less than 0.4s is cooled while remaining rows on the product plate linked to sequence the residual austenite is obtained, since there is a possibility that hole expansion is deteriorated, it is desirable that the above 0.4 s. [0096] 　Finish rolling process after completion of the cooling process at least the first cooling, it is desirable that the second cooling and the third step including cooling and winding. [0097] 　In the first cooling carried out immediately after the finish rolling step, at 15 ° C. / s or more at an average cooling rate, Ar 3 is cooled to below the transformation point (the temperature range of the fourth). The average cooling rate is pearlite generates during cooling is less than 15 ° C. / s, there may not tissue is obtained for the purpose. The upper limit of the cooling rate in the first cooling is not particularly necessary to limit, very difficult to control the cooling end temperature at a cooling rate exceeding 150 ° C. / s, since the lump made of microstructure becomes difficult 150 ° C. / s is preferably set to less. 　The cooling stop temperature is Ar 3 If it is lower than the transformation point, in the subsequent second cooling, may not be allowed to finely precipitate TiC in the ferrite at the austenite / ferrite transformation. On the other hand, the lower limit of the cooling stop temperature Keep this embodiment need not be particularly limited. However, as will be described later, the stopping temperature of the second cooling in order to express the precipitation strengthening of ferrite, and a temperature in excess of 600 ° C.. Its stop temperature of the first cooling since there is a possibility that precipitation strengthening is not obtained at 600 ° C. or less. Further, there is a possibility that the cooling stop temperature is not microstructure is obtained and Bs point (bainite transformation starting temperature) or less when it comes to ferrite and residual austenite is not obtained purposes. [0098] 　In the second cooling performed subsequent to the first cooling, 600 ° C. greater than the steel sheet below the average cooling rate of 10 ° C. / s, cooling to less than 1s to 700 ° C. or less 100s time. The cooling rate of the second cooling exceeds 10 ° C. / s, too moving speed of the interface of these two phases during transformation from austenite to ferrite is high, sufficient precipitation not catch up precipitation of Ti carbides at phase interfaces strengthening there may not be obtained. Also, transformation from austenite to ferrite is delayed, there is a case where the microstructure of interest can not be obtained. On the other hand, cooling in this temperature range as well as promote the transformation from austenite to ferrite, it is an object to obtain a strength of the steel sheet of the object to precipitate fine Ti carbides in the ferrite. Therefore, there is no particular need to limit the lower limit of the average cooling rate in the second cooling. In this embodiment, the second cooling is at a air cooling (cooling) in mind. 　Unless you heat input from the outside by the heating device, the cooling rate in air even at thickness of about half an inch is about 3 ° C. / s. [0099] 　Cooling time in the second cooling is less than 100s than 1s. Second cooling promotes phase separation of ferrite and austenite, as well as to obtain the second phase fraction of interest, to promote the precipitation strengthening by Ti fine carbides in the ferrite in the transformation is complete it is a very important step. Cooling time (no or second cooling) 1s than does tissue of interest can be obtained not proceed in ferrite transformation. Moreover, not obtained strength and hole expansion of the steel sheet of the object for deposition of Ti carbides in the ferrite after transformation does not proceed. For sufficiently advanced the ferrite transformation and carbide precipitation, it is desirable to cooling time than 3s. On the other hand, in the case of more than 100s not only the effect is saturated, significantly the productivity is lowered. Therefore, the cooling time less than 100s. If the cooling time is more than 15s, with an average particle size of the residual austenite tends to coarsen, since there is a concern that tissue perlite is mixed, it is desirable to be less than 15s cooling time. [0100] 　Cooling stop temperature in the second cooling, and 600 ° C. Ultra 700 ° C. or less (a temperature range of 5). Cooling stop temperature does not proceed precipitation of Ti carbides in the ferrite after transformation and is 600 ° C. or less, strength is lowered. On the other hand, the cooling stop temperature is not sufficient that phase separation of ferrite and austenite exceeds 700 ° C., can not be obtained area ratio of residual austenite of interest. Also, precipitation of Ti carbides in the ferrite becomes strength decreases with overaging. [0101] 　Ar 3 transformation point temperature (℃) are simplified manner can be calculated in relation to the steel ingredients, for example, by the following the following (x) equation. Ar 3 = 910-310 × C + 25 × (Si + 2 × Al) -80 × Mneq (x) 　wherein each element symbol in the formulas represents the content of each element contained in the steel (mass%). Further, Mneq, if not containing B, represented by the following (xi) equation, to contain B, represented by the following (xii) equation. = Mn + Mneq Cr + Cu + Mo + Ni / 2 + 10 × (Nb-0.02) (xi) Mneq = Mn + Cr + Cu + Mo + Ni / 2 + 10 × 　(Nb-0.02) +1 (xii) [0102] 　Following a second cooling, a third cooling. In the third cooling, the steel plate and cooled to 350 ° C. Ultra 450 ° C. or less at an average cooling rate from the fifth temperature region of 15 ° C. / s or higher above (temperature range of 6). The cooling rate is contaminated with pearlite structure is less than 15 ° C. / s, may not object to the tissue is obtained. End temperature in the cooling is identical to the coiling temperature. The upper limit of the cooling rate in the third cooling step is not particularly necessary to limit, considering the plate warping due to thermal strain, it is preferable to 300 ° C. / s or less. [0103] 　After the third cooling, winding the steel sheet at 350 ° C. Ultra 450 ° C. or less. Coiling temperature is not obtained residual austenite of interest carbides with a large amount of precipitate between bainite lath in the bainite transformation to progress after coiling exceeds 450 ° C., no sufficient elongation can not be obtained. Further, coarse carbides becomes a starting point of crack initiation, there is a possibility that the hole expansion properties are deteriorated. On the other hand, martensite coiling temperature is 350 ° C. or less can not be obtained residual austenite was produced in large amounts, sufficient elongation can not be obtained. It also degrades hole expansion to increase the origin of voids generated during widened hole. [0104] 　In after finish rolling cooling process, in order to express a precipitation strengthening by efficiently Ti carbides, it is necessary to control the cooling pattern itself up winding. Specifically, it is important that the total cumulative diffusion length Ltotal in a ferrite Ti ([mu] m) satisfies (v) below formula. 0.15 ≦ Ltotal ≦ 0.4 (v) [0105] 　Here, the total cumulative diffusion length Ltotal ([mu] m), the following (vi) diffusion length in the ferrite of Ti, which is defined by the equation L a ([mu] m), the short time until the wound from the cooling end temperature Delta] t (s) in a cumulative value, represented by the following (vii) expression. Ltotal = Σ (√ (D × (T + 273) × Δt)) (vii) [0106] 　Body diffusion coefficient in D × in formula (T + 273) is T (° C.) ([mu] m 2 A / s), as shown in the following (viii) equation, the diffusion coefficient of Ti D 0 ([mu] m 2 / s), represented by activation energy Q (kJ / mol) and the gas constant R (kJ / (mol · K )). Further, t is diffusion time (s), Delta] t is very small time when the time from the cooling end temperature to the winding separated by small time, in the present embodiment is 0.2 s. × D (T + 273) = D 0 × Exp (-Q / R × (T + 273)) (viii) [0107] 　When the total cumulative diffusion length Ltotal is less than 0.15 [mu] m, the precipitation of Ti carbide does not proceed during cooling, can not be obtained efficiently precipitation strengthening ability becomes nitrous aging. On the other hand, when the Ltotal exceeds 0.4 .mu.m, precipitation of Ti carbides during cooling is too advanced, it is impossible to obtain a still efficient precipitation strengthening ability becomes overaging. 　As described above, by optimizing the cooling condition in consideration of the C reduction due to miniaturization and Ti carbide precipitation in austenite grain size can be optimized tissue. [0108] 　The method for producing a steel sheet according to the present embodiment, furthermore, for the purpose of improving ductility by straightening and mobile dislocations introduced in the steel sheet shape, after the completion of all steps, reduction ratio from 0.1 to 2% it may be subjected to a skin pass rolling. Further, for the purpose of removal of the scale adhering to the surface of the hot-rolled steel sheet obtained, it may be subjected to pickling as necessary. Further, after pickling, it may be subjected to cold rolling to skin pass or reduction ratio of about 40% reduction of 10% or less in-line or off-line with respect to hot-rolled steel sheet obtained. [0109] 　Further, before and / or after the skin pass rolling, it is desirable to remove the scale of the surface. Not particularly specified for the method for removing scale. For example, it may in the apparatus in accordance with the hydrochloric acid or the general pickling using sulfuric acid, surface grinding using sander or the like, or a plasma, such as surface scarfing using a gas burner such as a line. [0110] 　In the method of manufacturing a steel sheet according to the present embodiment, after casting, after hot rolling, in either case after cooling, the plating applied by hot dipping line, to form a galvanized layer on the surface of the steel sheet it may be. By plating with molten plating line, thereby improving the corrosion resistance of the hot-rolled steel sheet. Furthermore, it may be subjected to additional surface treatment for these hot-rolled steel sheet. [0111] 　When the image is steel galvanized after pickling, immersed the resulting steel sheet in a galvanizing bath, may be optionally alloying (alloying process). By performing alloying treatment, the hot-rolled steel sheet, in addition to the improvement in corrosion resistance is improved welding resistance to various welding such as spot welding. 　2 shows an example of a method for manufacturing a steel sheet according to the present embodiment. Example [0112] 　The following examples illustrate the present invention more specifically, the present invention is not limited to these examples. [0113] 　Steel having the chemical components shown in Table 1 No. Converter cast slab of A ~ Z and a ~ d, and melted in a secondary refining process, and direct or re-heated after the continuous casting, rough rolling, subjected to finish rolling, cooled at runout table, coiling , to prepare a hot-rolled steel plate thickness is 2.3 ~ 3.4 mm (test No1 ~ 51). The production conditions of each steel are shown in Tables 2-1, 2-2 and Table 3-1 and 3-2. [0114] [Table 1] [0115] [table 2-1] [0116] [Table 2-2] [0117] [Table 3-1] [0118] [Table 3-2] [0119] 　In Table 2-1 and 2-2, the maximum temperature in the slab reheating the "heating temperature" in the slab heating step, shows the holding time at a predetermined heating temperature and "hold time". Moreover, the "total number of passes" in the rough rolling step, the rolling pass number of rough rolling, the "total reduction rate" the rolling reduction in the rough rolling to the end from the rough rolling start, "more than 20% the number of passes ", the number of performing the rolling of 20% or more of the reduction ratio at 950 ° C. or higher 1050 ° C. or less of the temperature range, the" total reduction rate ", rolling reduction in a temperature range of 950 ° C. or higher 1050 ° C. or less and the time of the "time to finish rolling start" from rough rolling step is completed to finish rolling process starts, the "average austenite grain size immediately before finish rolling", is rough bar to the first stand of the finishing rolling bite It shows an average particle size of austenite grains immediately before writing. The average austenite grain size in the finish rolling immediately before and quenched as possible the crop pieces are obtained by cutting a rough bar before entering the finish rolling at crop shear or the like is cooled to about room temperature, and parallel the rolling direction It was obtained by measuring with an optical microscope with a cross-section by etching so stand out the austenite grain boundaries. At this time, more than 20 field at more than 50 times magnification in the sheet thickness 1/4 position was measured by image analysis or point count method. [0120] 　In a further Table 3-1 and 3-2, a "rolling start temperature" in the finish rolling process, the temperature just before biting into the first stand of finish rolling, the "total number of paths", the rolling of the finish rolling the number of passes, the "total reduction rate", the reduction ratio in the finish rolling to the end from the finish rolling start, the "average rolling reduction of subsequent 3 pass", in finish rolling of continuous rolling of a normal multiple paths the average value of the reduction ratio in the final pass to the third pass including the last pass, the "finish rolling exit side speed", the output-side communication board speed at the roll stand after completion of the finish rolling final reduction pass, " the end temperature ", show a rolling stand out immediately after the side temperature of the finish rolling final pass. The reduction rate, even actual value calculated from a thickness may be set up value of the rolling stand. Although it is desirable that the temperature is measured at each step at a radiation thermometer or contact thermometer, but may be an estimate due to temperature models. [0121] 　Cooling step be carried out at run-out table, deposition control and microstructure control aspects from the first cooling, the second cooling is partitioned third cooling, and the subsequent winding. In Table 3-1 and 3-2, the "time to start of cooling" of the "first cooling", the time from leaving the rolling stand of the finishing rolling final pass to cooling by runout table is started, and "cooling rate", the average cooling rate by water cooling in the first cooling, the "cooling stop temperature" indicates the temperature of stopping the water cooling in the first cooling. Then the "second cooling" "cooling rate" of an average cooling rate due mainly to not apply water cooling, the "hold time", the time of air-cooling holding is not multiplied by the water, "cooling stop temperature" and shows a temperature completing the air-cooling holding is not pour water. The case of the second cooling time of cooling is 0, indicating that it did not stop the water cooling. Furthermore, the "cooling rate" in the "third cooling" is steel sheet again to start water cooling after air-cooling holding, the average cooling rate to wound, the "coiling temperature", water cooling was stopped, the winder the indicating the temperature just before winding into a coil. Because time is short from the water cooling stop to the winding, in the present invention, the cooling stop temperature of the third cooling is approximately equal to the coiling temperature. Finally the "total cumulative diffusion distance" indicates a value calculated by the above (vii) expression. [0122] 　Table 4-1, 4-2 and Table 5-1 and 5-2 in the production process in the resulting steel sheet microstructure described in Table 2-1, 2-2 and Table 3-1 and 3-2, mechanical properties, shows the surface properties and corrosion resistance. Samples were taken from the first position obtained 1/4 or 3/4 of the plate width of the steel sheet were observed microstructure in the sheet thickness 1/4 thickness using optical microscopy. As the adjustment of the sample was polished as an observation plane rolling direction of the plate thickness cross section was etched nital reagent at repeller reagent. Were classified microstructure from an optical microscope photograph of 500 times magnification was etched by nital reagent and repeller reagents. Of in the microstructure of Table 4-1 and 4-2, the martensite area ratio is the total area ratio of the fresh martensite and tempered martensite. [0123] [Table 4-1] [0124] [Table 4-2] [0125] [Table 5-1] [0126] [Table 5-2] [0127] 　It was also confirmed dispersion state of the residual austenite is the second phase by image analysis from optical micrograph of 500 times magnification was etched by repeller reagent. Wherein the dispersion state of the retained austenite, ferrite grains corner, what are dispersed like islands in the edge and the grain boundary "islands", those are distributed continuous to equilibrium in the rolling direction in islands " what is dispersed as rows "and mainly surround the grain boundary of ferrite grains were classified as" film-like ". [0128] 　Further measuring the area ratio and average particle size of the residual austenite by image analysis. Further, Ex.C / fsd table 4-1 and 4-2, a value obtained by dividing Table 1 Ex.C a (%) at an area ratio of residual austenite (%). The average crystal grain size of retained austenite obtained by a number average equivalent-circle diameter of the. Also, select any residual austenite, the distance to the residual austenite of the closest measured for 20 points, and the average value was designated as "mean value of the closest distance of residual austenite". [0129] 　Nano-hardness Hn was measured using a Hysitron Co. TriboScope / TriboIndenter. The measurement is performed under the conditions of hardness of the residual austenite of more than 20 points under a load of 1 mN, was calculated and the arithmetic mean and the standard deviation. [0130] 　Measurement of the density of the precipitates containing TiC "ferrite TiC density" were carried out by a three-dimensional atom probe measurement. First, from a sample to be measured, by cutting and electropolishing method, utilizing a focused ion beam processing method together with the electrolytic polishing method if necessary, to prepare a needle-like sample. The three-dimensional atom probe measurement can be obtained by reconstructing the accumulated data as the actual distribution image of atoms in real space. It was determined the number density of the TiC precipitates from the volume and TiC precipitates the number of three-dimensional distribution image of TiC precipitates. Measurements identifies the ferrite grains was performed with 5 or more of ferrite grains for each sample. Also, the size of the TiC precipitates from the lattice constants of the constituting atoms and of TiC observed TiC precipitates, the precipitate was size assuming calculated diameter spherical. Optionally diameter was measured for 30 or more TiC precipitates. Its average value was about 2 ~ 30 nm. [0131] 　Yield strength of the mechanical properties (YP), tensile strength (TS), and elongation (El) is, JIS Z 2241 taken in the direction perpendicular to the rolling direction from the position of 1/4 or 3/4 of the plate width ( using a No. 5 test piece of 2011), it was evaluated in compliance with the same standards. It was adopted hole expanding test as an indicator of hole expansion. Were taken test specimens from the hole expanding test specimens sampled position similar to the position, the Japan Iron and Steel Federation Standard JFS T 1001 (1996) was evaluated according to the test methods described. [0132] 　Then, as the rolling direction becomes the long side of the same position and the tensile test specimen taken a position to investigate the fatigue strength notch, and subjected to the collected fatigue test fatigue test piece having a shape shown in FIG. Here fatigue test piece shown in FIG. 1 is a cutaway specimens made in order to obtain fatigue strength notch. Test piece of Figure 1, chamfered side corner portions at 1R, are polished in the longitudinal direction in # 600. Notches to approximate fatigue evaluation in actual use of the automobile parts is assumed punched in hole expanding test piece likewise cylindrical punch. Punching clearance was 12.5%. However, the fatigue test piece was subjected to grinding of three mountains finish to a depth of about 0.05mm from the outermost layer. Fatigue test using a Schenk-type fatigue testing machine, the test method was according to JIS Z 2273 (1978) and JIS Z 2275 (1978). "Σ notch fatigue characteristics shown in Table 3-1, 3-2 WK and / TS" is a value obtained by dividing 200 million times fatigue strength obtained in this test with a tensile strength. [0133] 　Surface characteristics were evaluated by the surface defects and roughness of the pre-pickling. In the unevenness of the pattern and the surface of the scale defects caused even after pickling If this score is the reference hereinafter sometimes surface quality is evaluated from the inferior and consumers. Here surface defects represents the Si scale, scales, as a result of the check visually the presence or absence of scale defects spindle or the like, and if there is a scale defects indicated as "NG", the case where the scale defects is not indicated as "GOOD" It was. What these defects is not more than partially or standards was expressed as minor "OK". Roughness evaluated by Rz, shows values ​​obtained by the measuring method described in JIS B 0601 (2013). If Rz is 20μm or less, surface quality is a level no problem. [0134] 　The corrosion resistance was evaluated by the corrosion resistance after coating and chemical conversion treatability. Specifically, 2.5 g / m after pickling manufacturing steel sheet 2 subjected to chemical conversion treatment to deposit zinc phosphate coating, as a "chemical conversion treatability" At this stage, the measurement of the scale of the presence and P ratio It was carried out. [0135] 　Phosphate conversion treatment is a treatment using a chemical solution composed mainly of phosphoric acid and Zn ion, with the Fe ions eluted from the steel sheet, phosphophyllite: FeZn 2 (PO 4 ) 3 · 4H 2 is a chemical reaction that produces a crystal called O. Technical points phosphate conversion treatment is (1) and that the eluted Fe ions accelerate the reaction, to densely formed in (2) phosphophyllite crystals steel sheet surface. Especially for (1), when the oxide due to the formation of Si scale on the surface of the steel sheet is left, the dissolution of Fe is prevented, appeared portions conversion coating called scale does not adhere, Fe is not eluted it is, hopeite: Zn 3 (PO 4 ) 3 · 4H 2 to O iron surface called form abnormal chemical conversion coating that does not originally formed, degrade the performance after painting. Thus, is possible to normalize the surface to Fe ions Fe of the steel sheet surface by phosphoric acid may be eluted is sufficiently supplied becomes important. [0136] 　This For schedule can be confirmed by observation by the scanning electron microscope, and observed about 20 fields at a magnification of 1,000 diameters, and a "GOOD" a case where scale have entirely uniform adhesion can not be confirmed as no schedule. In addition, it was "OK" as a minor if the field of view schedule was confirmed less than 5%. More than 5% was evaluated as "NG" as there schedule. [0137] 　On the other hand, P ratio can be determined using X-ray diffraction apparatus, taking the X-ray diffraction intensity P of phosphophyllite (100) plane, the ratio of the X-ray diffraction intensity H of hopeite (020) plane, P ratio = it is valued at P / (P + H). That is, those P ratio that represents the ratio of hopeite and phosphophyllite in the film obtained by performing the chemical conversion treatment, phosphophyllite crystals steel sheet surface contains phosphophyllite many higher P ratio means that are densely formed. In general, it is P ratio ≧ 0.80 is, has been required to meet the corrosion resistance and paintability, and in severe corrosive environments such as snow-melting salt sprinkled area, P ratio ≧ 0. it is required is 85. [0138] 　For corrosion resistance after painting, it was evaluated by the following methods. Chemical subjected to the electrodeposition coating of 25μm thickness after treatment, were subjected to paint baking treatment of 170 ° C. × 20min. Thereafter, incision length 130mm with electrodeposition coating sharp knife tip to reach the base steel, at salt spray condition shown in JIS Z 2371, 700 h 5% salt spray at a temperature of 35 ° C. continued implementation. The laminated tape (Nichiban 405A-24 JISZ 1522) 130mm parallel to the cut portion of the length in the width 24mm over the notch portion was measured up to coating delamination width when was peeled it. The maximum coating film and peeling width is 4mm greater corrosion resistance after coating is to be inferior. [0139] 　Test No. 1,4,10,11,20 and 23 to 39 are examples of the present invention. These steel sheets, in order to satisfy all the requirements of the present invention, which has a strength of 540MPa class or grade, in balance with the strength, and the TS (MPa) × El (% ) not less than 19000MPa%, the hole expanding the value λ ≧ 70%, the fatigue properties σ notch WK is /TS≧0.35 and surface defects were insignificant below. That, and high strength, elongation, hole expansion, notch fatigue characteristics, was excellent in surface properties and corrosion resistance. [0140] 　On the other hand, test No. 2, 3, 5 to 9 and 12 to 19, 21, 22, although the chemical composition satisfies the requirements of the present invention, the microstructure is a comparative example departing from the provisions of the present invention. These steel sheets are stretched, hole expansion, notch fatigue properties, surface properties, was one or more poor result either corrosion resistance. In addition, test No. 12 steels 40 to 51 are comparative examples departing from the prescribed chemical composition present invention, Test No. therein Steel 45 and 46, in the microstructure satisfies the provisions of the present invention. However, also all these steel sheets, elongation, hole expansion, notch fatigue properties, surface properties, or corrosion resistance was inferior. Industrial Applicability [0141] 　According to the present invention has a tensile strength of at least 540 MPa, at the same time strength elongation balance, hole expansion, excellent corrosion resistance and notch fatigue properties, obtaining a high-strength processing-induced transformation type composite structure steel sheet excellent in more surface texture be able to. The strain-induced transformation type composite structure steel sheet can be suitably used as a steel sheet for the wheel disc and the like, has high industrial applicability. claims [Requested item 1] 　Chemical composition, in mass%, C: 0.075% than 0.150% or less, Si: 0.50% or less, Mn: 0.20 ~ 3.00%, P: 0.010% or less, S: 0.005% or less, Al: 0.040 ~ 1.500%, N: 0.0100% or less, Ti: 0.015 ~ 0.200%, Nb: 0 ~ 0.060%, Cu: 0 ~ 1 Pasento .20, Ni: 0 ～ 0.60 Pasento, Mo: 0 ～ 1.00 Pasento, V: 0 ～ 0.200 Pasento, Cr: 0 ～ 2.00 Pasento, W: 0 ～ 0.50 Pasento, Mg : 0 ~ 0.0100%, Ca: 0 ~ 0.0100%, REM: 0 ~ 0.100%, B: 0 ~ 0.0020%, the balance is Fe and impurities, and the following formula (i) The filling; 　Tissue at 1/4 thickness of the plate thickness, an area ratio, and 50% to 85% of polygonal ferrite, 3 to 10% of residual austenite, 5 to 47% of bainite, less than 1% of fresh total and a martensite and tempered martensite, and satisfies the following (ii) expression 　in said tissue, precipitates containing TiC is, 1 × 10 16 atoms / cm 3 is contained more, 　the average particle of the residual austenite diameter of 1.0 ~ 5.0 .mu.m circle equivalent diameter, 　the average value of the shortest distance of said residual austenite is 3.0 ~ 10.0 [mu] m, 　the average diameter of the precipitates is 3nm or less that processing-induced transformation type composite structure steel sheet characterized. -48 × Ti (N / 14 + S / 32) ≧ 0 (i) 0.01