Technical field
[0001]The present invention relates to an austenitic wear steel sheet used in the wear member.
BACKGROUND
[0002]Steel of a conventional wear-resistant member applications, are manufactured by and quenching the steel containing C of about 0.1 to 0.3 percent as disclosed in Patent Document 1 metallographic martensite that. Such Vickers hardness of the steel sheet is 400 ~ 600 Hv about a significantly higher, excellent wear resistance. However, martensite structure is inferior workability and toughness bending to very hard. Further, the steel sheet of the conventional wear-resistant member applications, although containing much C to increase the hardness, there is a possibility that the weld cracking occurs as containing C of 0.2% or more.
[0003]
　On the other hand, the high Mn cast steel is used as a material having both wear resistance and ductility. High Mn cast steel has good ductility and toughness for the matrix is ​​austenite. However, the high Mn cast steel, the surface portion due to rock impingement undergoes plastic deformation, deformation twins and, depending on the condition to cause work-induced martensitic transformation, only the hardness of the surface portion becomes remarkably high characteristics It has. Therefore, high Mn cast steel, the center even with enhanced abrasion resistance of the impact surface (surface portion) since the remains of austenite, can hold remain ductility and toughness excellent.
[0004]
　The high Mn cast steel, steel and stipulated in JIS G 5131, by increasing the C content and Mn content, mechanical properties, and wear resistance of austenitic wear steels with improved has been proposed and has (see etc. Patent documents 2-8).
[0005]
　In these high-Mn cast steel, if containing a large amount of C content is 1% or more to improve the wear resistance is large. The C content is more than 1% of the steel, even austenite having excellent ductility and toughness, by causes such as carbides many precipitates, there is a case where ductility and toughness is reduced. Further, it is necessary to add a large amount of Mn in order to stabilize the austenite when excessively reduced C content in order to improve the ductility and toughness, there is a disadvantage that the alloy cost becomes excessive.
[0006]
　Patent Document 9, as a way of avoiding the addition of large amounts of Mn and C, and process for producing a high Mn cast steel for use primarily strain-induced martensite is proposed. High C described above, the major mechanism for improving the wear resistance of austenitic wear steel high Mn, by twinning deformation of austenite caused by large deformation to be introduced into the surface of the steel material portion during a collision, such as rock, it is intended to cause a marked work hardening steel surface portion. The method described in Patent Document 9, by strong working of the steel material surface portion, by mainly transform the austenite to high carbon martensite and improves the wear resistance of the steel. Martensite containing much carbon, it is known that the hardness increases in proportion to the amount of C, it is very hard tissue. Therefore, according to the method described in Patent Document 9, it is possible to reduce the amount of C as compared with austenitic wear steel. Further, in the method described in Patent Document 9, the need to stabilize the austenite as austenitic wear steel is not, it is possible to reduce also the amount of Mn.
[0007]
　However, Patent Document 9, the step of performing homogenized 0.5-3 hours at 850 ~ 1200 ° C., the step of cooling to 500 ~ 700 ℃, 3 ~ step of performing 24 hours of perlite treatment, followed by 850 step of applying the austenitizing process again heated to ~ 1200 ° C., then, comprises the step of applying a water-cooled, is complicated and requires a long-time heat treatment.
CITATION
Patent Document
[0008]
Patent Document 1: Japanese Patent 2014-194042 JP
Patent Document 2: Japanese Patent Publication 57-17937 Patent Publication
Patent Document 3: Japanese Patent Publication 63-8181 discloses
Patent Document 4: Japanese KOKOKU 1-14303 JP
Patent Document 5: Japanese Kokoku 2-15623 Patent Publication
JP 6: Japanese Sho 60-56056 Patent Publication
Patent Document 7: Japanese Sho 62-139855 Patent Publication
Patent Document 8: Japanese Patent No. 1-142058 JP
Patent Document 9: Japanese Patent Laid-Open 11-61339 discloses
Summary of the Invention
Problems that the Invention is to Solve
[0009]
　In view of such circumstances, and an object thereof is to provide austenitic wear steel sheet excellent in abrasion resistance and strength and these contradictory toughness and ductility.
Means for Solving the Problems
[0010]
　In order to improve the abrasion resistance and strength of austenitic wear steel sheet preferably contains a large amount of hard alpha 'martensite and ε martensite in austenite. However, alpha 'when excessive content of martensite and ε martensite, in some cases the toughness and ductility of austenitic wear steel sheet is degraded. To obtain austenitic wear steel wear resistance and strength as well as toughness and ductility of, it is necessary that the austenitic wear steel sheet is an austenite phase mainly of tissue at the temperatures used. Further, in the steel alpha 'contain a martensite or ε martensite, and it is preferable that the tissue these tissues are not included in excess. Such tissue to the implementation, by adjusting the chemical composition of the steel, it is necessary and to control the stability of the austenite to the appropriate extent.
[0011]
　To further improve the wear resistance of austenitic wear steel sheet enhances the C content to about 1%, it causes a twinning deformation by plastic deformation due to rock impingement, remarkable work hardening the surface of the steel sheet part or causing, deformation-induced martensitic transformation by and generating the hard martensite, it is necessary to increase significantly the hardness of the steel sheet surface portion. Since high hardness martensite containing a large amount of carbon, causing the deformation-induced martensitic transformation of the steel sheet surface portion, thereby significantly improving the wear resistance of austenitic wear steel. From this point of view, as tissue austenitic wear steel sheet even tissue during manufacture mainly austenite to deformation-induced martensite transformation like in such rock has collided, the control stability of the austenite It is necessary to. To this end, controlling the content of C and Mn.
[0012]
　To improve the toughness of the steel sheet, austenite grains are (hereinafter, simply be referred to as a "grain" is.) Miniaturization of very effective, this can be achieved by hot rolling. Grain refining has the effect of improving toughness is proportional to "-1/2 power of the crystal grain size" as known in such relationship Hall-Petch. However, excessive miniaturization, by increasing the nucleation sites of carbides to be generated austenite grain boundaries, there is a drawback of increasing the amount of precipitation of grain boundary carbides. Grain boundary carbides are very hard and precipitation amount are steel toughness and ductility decreases with increasing. The present inventors have found that by controlling so as not to be excessively small while reducing the grain refinement has been found to be able to improve the toughness and ductility of the steel sheet.
[0013]
　As described above, the present invention is to appropriately control the chemical composition of the steel sheet, and hot rolling by it to achieve crystal grain refinement of steel, which provides austenitic wear steel below it is.
[1] The austenitic wear steel sheet according to one embodiment of the present invention, the chemical composition, in
mass%,
C: 0.2 ~ 1.6%, Si: 0.01 ~
2.00%, Mn: 2
~ 30.0% .5, P: 0.050% or
less, S: 0.0100% or
less,
Cu: 0 ~ 3.0%, Ni:
0 ~ 3.0%, Co: 0 ~ 3.0% , Cr:
0 ~ 5.0%, Mo: 0 ~ 2.0%, W: 0 ~ 2.0%, Nb: 0 ~ 0.30%, V: 0 ~ 0.30%, Ti: 0 ~ % 0.30, Zr: 0 ~ 0.30%, Ta: 0 ~ 0.30%, B: 0 ~ 0.300%, Al: 0.001 ~ 0.300%, N: 0 ~ 1.000 Pasento, O: 0 ～ 0.0100 Pasento, Mg: 0 ～ 0.0100 Pasento,

Ca:
0 ~ 0.0100%, REM: 0 ~ 0.0100%,
the balance is Fe and impurities,
　wherein C and each C the content by mass% of the Mn, and when expressed as Mn, - met 13.75 × C + 16.5 ≦ Mn ≦ -20 × C + 30,
　metal structure, volume fraction,
　austenite: 40% or more and less than 95%,
　an average particle size of the austenite is 40 ~ 300 [mu] m .
[2] The austenitic wear steel sheet according to [1], chemical composition, may satisfy the following expression.
　-C + 0.8 × Si-0.2 × Mn-90 × (P + S) + 1.5 × (Cu + Ni + Co) + 3.3 × Cr + 9 × Mo + 4.5 × W + 0.8 × Al + 6 × N + 1.5 ≧ 3.2
　Formula each element symbol in indicates the content by mass percent of the respective elements.
[3] The austenitic wear steel sheet according to [1] or [2], wherein the metal structure, by volume fraction,
　epsilon martensite: 0-60%,
　alpha 'martensite: 0-60%,
　wherein ε sum of martensite and the alpha 'martensite may be 5-60%.
[4] [1] The austenitic wear steel sheet according to any one of - [3], wherein the chemical composition, in
mass%, O: 0.0001 - 0.0100%,
Mg content, total Ca content and REM content: may be 0.0001 to 0.0100%.
[5] The austenitic wear steel sheet according to [4], wherein the chemical composition, in
mass%, S: a 0.0001 to 0.0050%,
　the content by mass percent of O and S O / S ≧ 1.0 may satisfy.
[6] [1] The austenitic wear steel sheet according to any one of to [5], wherein the chemical composition, represents the content by mass percent of C and Mn C, respectively, and the Mn
　when, it may satisfy -6.5 × C + 16.5 ≦ Mn ≦ -20 × C + 30.
[7] [1] The austenitic wear steel sheet according to any one of to [6], wherein the chemical composition, in
mass%, Cu: 0 - 0.2%
　may be.
The invention's effect
[0014]
　According to this aspect of the present invention, wear resistance and strength and excellent austenitic wear steel these contradictory toughness and ductility (hereinafter, simply referred to as "steel plate".) Can be provided. Specifically, according to the above aspect of the present invention, by appropriately controlling the chemical composition and the metal structure suitably controlled by hot rolling, by achieving grain refinement of steel, resistance it is possible to provide a steel sheet excellent in abrasion resistance and strength as well as toughness and ductility. Steel sheet according to the present invention, a variety of thickness from about 3mm thickness up to about 200 mm, can be produced having a width of about 5 m, a length of about 50 m. Therefore, the steel sheet according to the present invention, the impact of such crusher liners is exerted, not only to a relatively small wear-resistant member can be used as a very large construction machinery members and abrasion structural member. Further, according to the steel sheet according to the present invention, the steel pipe having the same characteristics as the steel sheet according to the present invention, it is also possible to produce shaped steel. Further in accordance with a preferred embodiment of the present invention, it is possible to utilize the oxysulfides suppressing grain coarsening in the welded portion, it is possible to provide a steel sheet excellent in toughness of the weld.
DESCRIPTION OF THE INVENTION
[0015]
　It will be described in detail below austenitic wear steel sheet according to the present embodiment. In the present embodiment, the tissue or steel utilizing martensitic transformation of the austenitic structure mainly of high hardness austenite as described above, is defined as the austenitic wear steel. Specifically, the volume fraction of austenite is less than 40%, the steel sheet of less than 95%, defined as an austenitic wear steel.
　First, a description will be given reasons for limiting the respective components in the austenitic wear steel sheet according to the present embodiment. Incidentally, "%" for the content of elements, unless otherwise specified, means "% by mass".
[0016]
[C: 0.2 ~ 1.6%]
　C stabilizes the austenite and improves the wear resistance. In order to improve the wear resistance of the steel sheet, C content is required to be not less than 0.2%. Particularly high when wear resistance is needed, C content is 0.3% or more, 0.5% or more, and preferably 0.6% or more, or 0.7% or more. On the other hand, when the C content exceeds 1.6%, that carbides are generated coarse and large amounts in the steel, it is impossible to obtain a high toughness in the steel plate. Therefore, C content is at most 1.6%. C content is more preferably set to 1.4% or less, or 1.2% or less. For further improving the toughness, C content is 1.0% or less, or 0.8% or less.
[0017]
[Si: 0.01 ~
　2.00%] Si is usually deoxidizing element, but also a solid solution strengthening element, the effect of suppressing the formation of carbides of Cr and Fe. The present inventors, the element for suppressing generation of carbides and various studies, the Si By including a predetermined amount, and found that the formation of carbides is suppressed. Specifically, the present inventors have an Si content is 0.01 to 2.00% was found that the formation of carbides is suppressed. The Si content of less than 0.01% can not be obtained the effect of suppressing the generation of carbide. On the other hand, the Si content of 2.00% exceeds generates a coarse inclusions in the steel and cause deterioration of ductility and toughness of the steel sheet. Si content is 0.10% or more, or it is preferable that 0.30% or more. Further, Si content 1.50% is less, or it is preferable that 1.00% or less.
[0018]
[Mn: 2.5 ~ 30.0%, - 13.75 × C + 16.5 ≦ Mn ≦ -20 × C +
　30] Mn is an element which stabilizes austenite with C. Mn content is 2.5 to 30.0%. To improve the austenite stabilizing, Mn content is 5.0% or more, 10.0% or more, it is preferable to 12.0% or higher, or 15.0% or more. Mn content is 25.0% or less, it is preferable to 20.0% or less, or 18.0% less.
[0019]
　In terms of austenite stabilizing, Mn content in relation to the C content, -13.75 × C + 16.5 (%) or more, -20 × C + 30 (%) or less (i.e., -13.75 × C + 16 .5 ≦ Mn ≦ -20 × C + 30) to. This is a relationship of Mn content and the C content is less than -13.75 × C + 16.5 (%), because the volume fraction of austenite is less than 40%. Also, in relation to the Mn content C content, when it comes to -20 × C + 30 (%) greater, because the volume fraction of austenite is 95%.
[0020]
　In order to keep further favorable ductility and toughness, Mn content is in relation to the C content, -6.5 × C + 16.5 (%) or more, -20 × C + 30 (%) or less (i.e. -6 it is preferable that the .5 × C + 16.5 ≦ Mn ≦ -20C + 30). The relationship between the Mn content and the C content by controlling the above range, it is possible to reduce the volume fraction of martensite, in particular alpha 'martensite contained in the steel sheet structure, the ductility and toughness of the steel sheet it can be significantly improved. Since the influence of C is very large relates to the stabilization of austenite in the steel sheet according to the present embodiment, the relationship between the Mn content and the C content of the is particularly important.
[0021]
[P: 0.050% or less]
　P is segregated at grain boundaries, as it reduces the ductility and toughness of the steel sheet, it is preferable to reduce as much as possible. Therefore, the P content to 0.050% or less. P content is preferably 0.030% or less, or 0.020% or less. P is generally contained as impurities from scraps or the like at the time of molten steel production, but there is no need to particularly limit the lower limit, the lower limit is 0%. However, excessive reduction of P content, there is a case where the production cost is increased. Therefore, the lower limit of the P content less than 0.001%, or 0.002% or more.
[0022]
[S: 0.0100% or less]
　S is an impurity, the excessive content segregates in the grain boundary, or generates a coarse MnS, lowers the ductility and toughness of the steel sheet. Therefore, the S content is set to 0.0100% or less. S content 0.0060% is less, it is preferable that 0.0040% or less, or 0.0020% or less. The lower limit of the S content is 0%. S as described later, O, and Mg, Ca and / or REM (rare earth metals: Rare-Earth Metal) and by making in the steel to produce a fine oxysulfides, inhibit grain growth of the austenite , toughness of the steel sheet, in particular welded heat affected zone: the effect of improving the toughness of (HAZ heat-affected Zone). To obtain the above effect, the S content 0.0001% or more, 0.0005% or more, or may be 0.0010% or more. In the present embodiment, "oxysulfide", not only the compounds containing both O and S, but also an oxide and sulfide.
[0023]
　Steel sheet according to the present embodiment, in addition to the essential elements mentioned above, Cu is further shown below, Ni, Co, Cr, Mo, W, Nb, V, Ti, Zr, Ta, B, N, O, Mg, Ca and may be selectively contain one or more kinds of REM. Inclusion of these elements is not essential, the lower limit of the content of all these elements is 0%. Incidentally, Al to be described later is not arbitrary element, an essential element.
[0024]
[Cu: 0 ~ 3.0%, Ni: 0 ~ 3.0%, Co: 0 ~
　3.0%] Cu, Ni and Co improves the toughness of the steel sheet, is and stabilizes the austenite. However, Cu, Ni, when the content in one of Co exceeds 3.0%, the effect of improving the toughness of the steel sheet is saturated and the cost increases. Therefore, the case of containing these elements, the content of each element, respectively, and 3.0% or less. Cu content, Ni content and Co content are respectively 2.0%, 1.0%, is preferably 0.5% or less, or 0.3% or less. In particular, for Cu content, more preferably not more than 0.2%. For austenite stabilization, Cu content is 0.02% or more, 0.05% or more, or may be at least 0.1%, respectively, Ni content and Co content of 0.02% or more, 0 .05% or more, 0.1% or more, or may be 0.2% or more.
[0025]
[Cr: 0 ~
　5.0%] Cr improves the work hardening properties of the steel. If Cr content exceeds 5.0%, to promote the precipitation of grain boundary carbides lowers the toughness of the steel sheet. Therefore, Cr content is 5.0% or less. Cr content is 2.5% or less, or preferably to 1.5% or less. To improve the work hardening characteristics, Cr content is 0.05% or more, or may be 0.1% or more.
[0026]
[Mo: 0 ~ 2.0%, W: 0 ~
　2.0%] Mo and W, to strengthen steel, to reduce the activity of C in the austenite phase, the Cr and Fe precipitated in the austenite grain boundaries suppressing the precipitation of carbides, it improves the toughness and ductility of the steel sheet. However, the effect can be excessively is contained whereas saturated, cost increases. Therefore, Mo content and W content is 2.0% or less, respectively. Preferably, Mo content and W content of 1.0% each or less, 0.5% or less, or 0.1% or less. In order to ensure the above effects, each Mo content and W content, 0.01% or more, 0.05% or more, or may be 0.1% or more.
[0027]
[Nb: 0 ~ 0.30%, V: 0 ~ 0.30%, Ti: 0 ~ 0.30%, Zr: 0 ~ 0.30%, Ta: 0 ~
　0.30%] Nb, V, Ti, Zr and Ta, to produce a precipitate, such as carbonitrides in steel. These precipitates, by suppressing the coarsening of crystal grains during solidification of the steel, to improve the toughness of the steel. Further, the element reduces the activity of C and N in austenite, suppresses the formation of carbides such as cementite or graphite. Furthermore, the elements, to strengthen the steel by solid solution strengthening and precipitation.
[0028]
　Nb content, V content, Ti content, when the content in one of a Zr content and Ta content exceeds 0.30%, precipitates significantly coarsened, ductility and toughness of the steel sheet there is a case to be lowered. Therefore, Nb content, V content, Ti content, Zr content and Ta content respectively, and 0.30% or less, 0.20% or less, 0.10% or less or 0.01% or less it is more preferable. Furthermore, Nb content, V content, Ti content, Zr content and Ta total 0.30% of the content of the following, or even more preferably 0.20% or less. For improving the toughness and increasing the strength of steel, each Nb content and V content of 0.005% or more, 0.01% or more, or may be 0.02% or more. For the same reason, Ti content, respectively Zr content and Ta content, 0.001% or more, or it may be 0.01% or more.
[0029]
[B: 0 ~ 0.300%] B
　suppresses grain boundary fracture by segregation to the austenite grain boundaries, thereby improving the strength and ductility of the steel sheet. However, when the B content exceeds 0.300%, the toughness of the steel sheet is degraded. Therefore, B content is at most 0.300%. B content is preferably not more than 0.250%. To suppress grain boundary fracture, B content 0.0002% or more, or may be 0.001% or more.
[0030]
[Al: 0.001 ~
　0.300%] Al is a deoxidizing element, is a solid solution strengthening element, like Si, suppresses the formation of Cr and Fe carbides. The present inventors have made various studies and element for suppressing generation of carbides, the Al content is equal to or greater than a predetermined amount, and found that the formation of carbides is suppressed. Specifically, the present inventors have found that the Al content is 0.001 to 0.300%, found that generation of carbides is suppressed. The Al content of less than 0.001%, not obtained the effect of suppressing the formation of carbides. On the other hand, the Al content 0.300 percent, to generate coarse inclusions, which can cause deterioration of ductility and toughness of the steel sheet. Al content is 0.003% or more, or it is preferable that 0.005% or more. Further, Al content 0.250% is less, or it is preferable that 0.200% or less.
[0031]
[N: 0 ~ 1.000%]
　N is an element effective for strength improvement of stabilization and steel sheet austenite. N as an element of austenite stabilizing, with C the same effect. N does not adversely affect such as toughness degradation due to grain boundary precipitation, is greater than C effect of increasing the strength at cryogenic temperatures. Further, N represents, by coexisting with the nitride forming element, has the effect of dispersing the fine nitrides in the steel. When N content exceeds 1.000%, the toughness of the steel sheet is remarkably deteriorated. Therefore, N content is at most 1.000%. N content 0.300% below 0.100% or less, or more preferably 0.030% or less. N is sometimes mixed a certain amount as an impurity, such as for increasing the strength of the, the N content may be 0.003% or more. N content is 0.005% or more, and more preferably 0.007% or more, or 0.010% or more.
[0032]
[O: 0 ~ 0.0100%] O
　is sometimes mixed a certain amount in the steel as an impurity, it has the effect of higher toughness by grain refinement in HAZ. On the other hand, if the O content exceeds 0.0100% by segregation of the coarse and grain boundaries of oxides, which may ductility and toughness in the HAZ is lowered rather. Therefore, O content is 0.0100% or less. O content is more preferably set to 0.0070% or less, or 0.0050% or less. For toughened, O content of 0.0001% or more, or may be 0.0010% or more.
[0033]
[Mg: 0 ~ 0.0100%, Ca: 0 ~ 0.0100%, REM: 0 ~
　0.0100%] Mg, Ca and REM are large amount generated by the high Mn steel, the ductility and toughness of the steel sheet inhibiting the production of MnS significantly reduce. On the other hand, when the content of these elements is excessive, coarse inclusions in steel large amount to generate and cause deterioration of ductility and toughness of the steel sheet. Therefore, Mg content, Ca content and REM content is respectively to 0.0100% or less. Mg content, respectively Ca content and REM content, 0.0070% or less, or more preferably 0.0050% or less. For suppressing the formation of MnS, Mg content, respectively Ca content and REM content may be 0.0001% or more. Mg content, respectively Ca content and REM content, 0.0010% or more, or may be 0.0020% or more.
　Incidentally, REM (rare earth metal element) is, Sc, means a total of 17 elements consisting of Y and lanthanoid. The content of REM, means the total content of these 17 elements.
[0034]
[O: 0.0001 to 0.0100 percent, as well as, Mg content, total Ca content and REM content: 0.0001 to 0.0100%
　for the reason described below, the O content of 0.0001 to in addition to a 0.0100%, Mg content, the total Ca content and REM content is preferably be from 0.0001 to 0.0100%. That, Mg, it is preferable that the content of at least one element in the Ca and REM and from 0.0001 to 0.0100 percent. At this time, the O content is 0.0002% or more, may be 0.0050%. Mg content, Ca content and REM content of total 0.0003% or more, 0.0005% or more, or may be 0.0010% or more, 0.0050% or less, or even 0.0040% or less good.
[0035]
　O content was 0.0001% or more, Mg content, why the total Ca content and REM content is 0.0001 to 0.0100%, the oxidation of Mg, Ca and / or REM in the steel to generate object is to prevent the coarsening of crystal grains in the HAZ of the steel sheet. Crystal grain size of austenite of HAZ obtained by the pinning effect of grain growth by the oxide, if standard welding conditions, 300 [mu] m becomes several tens [mu] m, does not exceed 300 [mu] m (where the steel plate (mother unless the crystal grain size of austenite of wood) exceeds 300 [mu] m). Thus, it is preferred to incorporate the element for controlling the crystal grain size of austenite of steel including HAZ to 300μm or less (O, Mg, Ca and REM).
[0036]
[S: 0.0001 ~ 0.0050%, O / S ≧ 1.0]
　S is, O, and Mg, in order to produce a Ca and / or REM and oxysulfides, effective grain refinement it is an element. Therefore, O in the steel, as well as Mg, In case of containing S with Ca and / or REM in order to obtain the effect of increasing the toughness by grain refinement in HAZ, S content is 0.0001% it is preferable that the above. Furthermore, O in the steel, as well as Mg, if the inclusion of S with Ca and / or REM, S content is preferably 0.0050% or less in order to obtain a better steel sheet ductility and toughness.
[0037]
　If O, and Mg, are contained S with Ca and / or REM in the steel, that S content and O content satisfy the relationship of O / S ≧ 1.0, in HAZ, the grain refining the effect of higher toughness due can be remarkably exhibited. Since the sulfide is thermally unstable with respect to oxide, the ratio of S in the precipitated particles is increased, there is a case where stable pinning particles at high temperatures can not be ensured. Therefore, if the O content is set to 0.0001 to 0.0100%, Mg content, and 0.0001 to 0.0100% of total Ca content and REM content, which contained S in the steel, S the content is set to 0.0001 to 0.0050%, it is more preferable that O content and the S content and O / S ≧ 1.0. Preferably the O / S ≧ 1.5, or O / S ≧ 2.0. O content and S content that satisfy the above conditions, precipitation state of oxysulfide in the steel is more preferred, can be remarkably exhibited a grain refining effect. By the effect, if an average particle size of austenite steel sheet less than 150 [mu] m, if the standard welding condition, the average grain size of austenite in the HAZ can be made 150 [mu] m or less. Although not particularly necessary to define the upper limit of O / S, 200.0 or less, 100.0 or less, or 10.0 may be less.
[0038]
　In the steel sheet according to the present embodiment, the balance other than the above components, Fe and impurities. Steel and the impurity in the present embodiment, in producing the steel sheet industrially, starting raw materials such as ores and scrap, a component mixed by various factors of the manufacturing process, according to this embodiment means what is acceptable to the extent that the properties do not adversely affect.
[0039]
[-C + 0.8 × Si-0.2 × Mn-90 × (P + S) + 1.5 × (Cu + Ni + Co) + 3.3 × Cr + 9 × Mo + 4.5 × W + 0.8 × Al + 6 × N + 1.5 ≧ 3.2]
　the present inventors have, -C + 0.8 × Si-0.2 × Mn-90 × (P + S) + 1.5 × (Cu + Ni + Co) + 3.3 × Cr + 9 × Mo + 4.5 × W + 0.8 × Al + 6 × N + 1.5 CIP values represented in the If it is 3.2 or more, to obtain a finding that can improve the corrosion resistance of the steel sheet. Further, the present inventors have obtained the finding that it improved corrosion wear due to material slurry are mixed, such as gravel brine is corrosive environment by improving the corrosion resistance. The upper limit of the CIP value is not particularly limited, for example, 65.0 or less, 50.0 or less, 40.0 or less, may be 30.0 or less or 15.0 or less.
[0040]
　As CIP value is larger, it is possible to improve the corrosion resistance and corrosive wear resistance of the steel sheet, in the case of CIP value is less than 3.2, is not significantly improved corrosion resistance and corrosive wear resistance of the steel sheet.
　Incidentally, the C in formula, the Si, the Mn, the P, the S, the Cu, the Ni, the Co, the Cr, the Mo, the W, the Al and the N is in mass% each shows the content of the element. If that does not contain the element, 0 is substituted.
[0041]
[Volume fraction of austenite: 40%, less than 95%
　steel sheet according to the present embodiment is Au State based antiwear steel utilizing deformation-induced martensite transformation is required predetermined amount of austenite. Steel sheet according to the present embodiment, and the volume fraction of austenite in the steel sheet less than 40% or more and 95%. If necessary, the volume fraction of austenite, 90% or less, 85% or less, or of 80% or less. In order to ensure the wear resistance of the steel sheet, the volume fraction of austenite is 40% or more. The volume fraction of austenite, 45% or more, 50% or more, it is preferable that 55% or more or 60% or more.
[0042]
[Epsilon martensite and alpha 'volume fraction of martensite: 5 to 60% total volume fraction of epsilon martensite: 0-60%, alpha' volume fraction of martensite: 0-60%]
　present steel sheet according to the embodiment, by containing a predetermined amount of ε martensite and alpha 'martensite is preferable because it is possible to obtain more easily the desired hardness or strength. ε total volume fraction of martensite and alpha 'martensite, 5% or more, 10% or more, or is preferably 15% or more. Further, it is preferable that the total volume fraction of ε martensite and alpha 'martensite to obtain ductility and toughness of the steel sheet is 60% or less. Furthermore, epsilon volume fraction of martensite and alpha 'martensite 55% in total less, 50% or less, 45% or less, and more preferably 40% or less.
[0043]
　Metal structure of the steel sheet according to the present embodiment, austenite, to consist of ε martensite and alpha 'martensite preferred. Incidentally, when the tissue analysis by X-ray diffraction, iron carbonitride such as cementite, carbonitride of a metal element other than iron, Ti, Mg, oxysulfides such as Ca and REM, as well as other inclusions traces of precipitates and inclusions such as (e.g., less than 1%) suggests measurement of the presence of some cases obtained. However, in the conventional light microscopy, they are little or not observed, or, be observed austenite are finely dispersed, such as the boundary within or organizations of each tissue of ε martensite or alpha 'martensite. Therefore, it shall not be metallographic regarded in the land of the so-called steel (matrix).
[0044]
　Austenite, a volume fraction of ε martensite and alpha 'martensite is determined by the following method.
[0045]
　Mid-thickness portion (from the surface of the steel sheet 1 / 2T depth (T is thickness)) of the steel sheet is cut out a sample from. And observation surface a plane parallel to the thickness direction and the rolling direction of the sample, after the mirror-finished by buffing the observation surface, removing distortion by electrolytic polishing or chemical polishing.
　With respect to the observation plane, using an X-ray diffraction apparatus, and the average value of the integrated intensity of (311) (200) (220) plane of austenite of a face-centered cubic structure (fcc structure), close-packed hexagonal lattice structure (hcp structure) epsilon martensite (010) (011) (012) and the average value of the integrated intensity of the surface, a body-centered cubic structure (a bcc structure) alpha 'martensite (220) (200) (211) plane of the and a mean value of the integrated intensity, obtained austenite, epsilon the volume fraction of martensite and alpha 'martensite.
[0046]
　However, if C content is more than 0.5%, alpha 'martensite body-centered tetragonal structure (bct structure), and the diffraction peak obtained by X-ray diffraction measurement, a double for the anisotropic crystal structure there is a case to be the peak. In such a case, the total integrated intensity of each peak to obtain the volume fraction of alpha 'martensite.
　If C content is less than 0.5%, alpha 'close to the body-centered a / c ratio of the square lattice 1 of martensite, alpha' body-centered cubic structure (bcc structure) of martensite and body-centered tetragonal structure peaks of X-ray diffraction of the (bct structure) can hardly separate. Therefore, from the average value of the integrated intensity of (220) (200) (211) plane of the body-centered cubic structure (bcc structure), to obtain the volume fraction of alpha 'martensite. If C content is capable of separating the peak even less than 0.5%, the sum of the respective integral intensities to determine the volume fraction of alpha 'martensite.
[0047]
Average particle size of austenite: 40 ~ 300 [mu] m]
　is first described high C and high Mn toughness reduction mechanism of austenitic steel. The steel sheet according to the present embodiment, due to the high C content and Mn content, not the austenite grain boundaries but also a large number of iron carbide to generate in the grains. These carbides, so compared to the iron matrix phase is a hard, increasing the stress concentration of the carbide surrounding when subjected to external forces. Thus, a crack is generated in the carbide or between carbide surrounding the cause of breakage. When subjected to external force, stress concentration occupying bring the steel to fracture is reduced as the grain size of austenite is small. However, excessive miniaturization has the disadvantage that increases the nucleation sites carbide generating austenite grain boundaries, thus increasing the amount of precipitation of carbonitrides. Grain boundary carbides are very hard and precipitation amount are steel toughness and ductility decreases with increasing. The present inventors have found that by optimizing the grain size was found to be improved toughness and ductility of the steel sheet.
[0048]
　In this embodiment, while suppressing the generation of carbides, basically due to the miniaturization of austenite, thereby improving the toughness of the steel sheet. Steel sheet according to the present embodiment, as described above, at a volume fraction of 40% or more, including austenite less than 95%. Further, the steel sheet according to the present embodiment, since it is produced by hot-rolling, as described later in detail, the austenite in the steel sheet is refined by rolling the heat, has excellent toughness.
[0049]
　Since the austenite grain boundaries is also a nucleation site carbides, the austenite is excessively fine, the generation of carbides is promoted. When carbides are excessively generated, there is a case where the toughness of the steel sheet is degraded. From this point of view, the average particle size of austenite in the steel sheet is not less than 40 [mu] m. The average particle size of austenite in the steel sheet, 50 [mu] m or more, 75 [mu] m or more, or it is preferable to 100μm or more. On the other hand, when the average particle size of austenite is 300μm greater, it is impossible to ensure a sufficient toughness at low temperatures of about -40 ° C.. Therefore, the average grain size of austenite in the steel sheet to 300μm or less. The average particle size of austenite in the steel sheet is preferably set to 250μm or less, or 200μm or less. Incidentally, upper and lower limits of the average particle size of the austenite, hot rolling and in accordance with the present embodiment, it is possible values ​​achieved by the pinning effect due oxysulfide like.
[0050]
　According to the steel sheet according to the present embodiment, for example, even when exposed to a high temperature by welding, it is possible to reduce the average particle size of austenite in the HAZ. For example, if the plate thickness 20mm or more of the steel sheet, covered electrode welding heat input to the steel plate 1.7kJ / mm (SMAW: Shielded Metal Arc Welding) even when subjected to, FL (melting at mid-thickness portion the average particle size of the HAZ austenite line) near can be maintained in the range of 40 ~ 300 [mu] m. Further, the steel plate depending on the average particle size of austenite of (matrix), as described above, Mg, further on which contains Ca and / or REM, in mass ratio of O and S in the steel sheet O / S ≧ with 1.0, an average particle size of austenite in the HAZ of FL vicinity after the welding can be maintained in the range of 150 [mu] m or less, or 40 ~ 150 [mu] m. As a result, it is possible to increase the toughness of the welded joint obtained by welding a steel sheet according to the present embodiment. Also, in welding the steel sheet according to the present embodiment, highly efficient method of welding, such as increasing the heat input can be used.
[0051]
　The following describes the measurement method of the average particle diameter of austenite in the present embodiment. First, (1 / 2T depth from the surface of the steel sheet (T is thickness)) mid-thickness portion of the steel sheet is cut out a sample from. And observation surface of a cross section parallel to the rolling direction and the thickness direction of the steel sheet, after the mirror with an alumina polishing or the like, corrodes in nital solution or picral solution. Metallographic observation surface after corrosion by observing enlarged due optical microscope or an electron microscope to obtain an average particle size of the austenite. More specifically, in the observation plane, a 1 mm × 1 mm or more field of view magnified at 100 times, JIS Z0551: 2013 Annex C. The cutting method according to the second straight test lines, obtaining the mean intercept length of the crystal grains 1 per austenite observed during the observation field of view, that the average particle diameter of this, to obtain an average particle size of austenite.
[0052]
　Described below achieve means an average particle size of the austenite. This embodiment, since it relates to steel sheets, the refinement of the crystal grain size of austenite in the steel sheet (base material), can be utilized recrystallized by hot-rolling. The average particle size of austenite after recrystallization is expressed, for example, the following equation (1). D (1) below wherein rex is the average particle size of austenite after recrystallization, D 0 is the average particle size of the pre-recrystallization austenite, epsilon is the plastic strain due to hot rolling, p and q is a positive constant, r is a negative constant.
[0053]
　Ｄ rex＝ｐ×Ｄ 0 q×ε ｒ　・・・　（１）
[0054]
　According to the above (1), and maximize the plastic strain during hot rolling, it is possible to obtain the austenite having a predetermined grain size by performing a plurality of times of rolling. For example, p = 5, q = 0.3, r = -0.75, when the average particle size of the initial particle size i.e. recrystallization prior austenite is 600 .mu.m, the mean particle size of after recrystallization austenite 300μm or less to a, it is necessary that the plastic strain during hot rolling 0.056 or more. Under the same conditions, the average particle diameter of the after recrystallization austenite to the 100μm or less is that the plastic strain during hot rolling is required to be 0.25 or more. Further, under the same conditions, in order to maintain an average particle size of after recrystallization austenite above 20μm, the plastic strain during hot rolling may be set to 2.1 or less. Thus, in order to obtain austenite having a predetermined grain size, the plastic strain during hot rolling is calculated by the equation (1) is a measure, in fact, the grain growth of the austenite after recrystallization it is necessary to fine-adjusted to account for effects of and multipass rolling.
[0055]
　The present inventors have studies to date, including the foregoing, the manufacturing method described below, it was confirmed to be able to manufacture a steel sheet according to the present embodiment.
[0056]
(1) melted slab production process
　melting and slab manufacturing process need not be particularly limited. That is, subsequent to melting due converter furnace or an electric furnace and subjected to various secondary refining is adjusted such that the chemical composition described above. Then, it may be manufactured slabs by a method such as ordinary continuous casting.
[0057]
(2) hot-rolling process
　slabs produced in the manner described above, after heating, is subjected to hot rolling. Slab heating temperature is preferably 1250 ° C. ultra ~ 1300 ° C.. Heating the slab to 1300 ° C. greater than if the reduced yield by the steel sheet surface oxidize and austenite become coarse, may not be readily miniaturized by hot rolling after slab heating. Therefore, the slab heating temperature is 1300 ° C. or less.
　Cumulative rolling reduction in the temperature range of 900 ~ 1000 ° C. is 10 to 85%. Thus, it has been confirmed to be able to an average particle size of austenite 40 ~ 300 [mu] m.
[0058]
　However, even in the slab heating temperature is 1200 ~ 1250 ° C., less than the cumulative rolling reduction in the temperature range of 900 ~ 1000 ℃ 10 ~ 30%, and by satisfying the condition to be described later, the steel sheet according to the present embodiment manufactured It has been confirmed to be able to.
[0059]
　In the present embodiment, in addition to the above conditions, the finishing temperature of hot rolling has been confirmed that by controlling the (hereinafter sometimes referred to as a rolling finishing temperature) is also important. When the rolling finishing temperature is lower than 900 ° C., and if the austenite is not completely recrystallized, even austenite recrystallizes, excessively miniaturized, there is a case where the average particle diameter is less than 40 [mu] m. When austenite is not completely recrystallized, is twin many dislocations and variations introduced in the metal structure, there is a case where the carbide is produced in a large amount in the subsequent cooling. When carbides are produced in large quantities in the steel, reduce the ductility and toughness of the steel sheet. By the rolling finishing temperature and 900 ° C. or higher, it is possible to prevent the above problem. Therefore, in the present embodiment, the rolling finishing temperature to 900 ° C. or higher.
[0060]
　In cooling after hot rolling, except when performing a heat treatment described later, performing the accelerated cooling. The purpose of accelerated cooling suppresses the formation of carbides after hot rolling, in order to increase the ductility and toughness of the steel sheet. To suppress the formation of carbides, from the viewpoint of whether the thermodynamic point of view and diffusible, is necessary to minimize the residence time in the 850 ~ 550 ° C. is a temperature range in which carbides are precipitated in steel is there.
[0061]
　The average cooling rate during accelerated cooling to 1 ° C. / s or higher. If the average cooling rate during accelerated cooling is less than 1 ° C. / s, the effect of accelerated cooling (generation suppressing effect of carbide) is because there may not be sufficiently obtained. On the other hand, when the cooling rate during accelerated cooling is higher than 200 ° C. / s, a large amount of generated by ε martensite and alpha 'martensite, toughness and ductility of the steel sheet may be deteriorated. Therefore, the average cooling rate at the time of accelerated cooling is not more than 200 ° C. / s.
[0062]
　It accelerated cooling after hot rolling begins from the high temperature side as possible. Since the temperature at which carbides begin to actually deposited is lower than 850 ° C., the cooling start temperature, and 850 ° C. or higher. Cooling end temperature, and 550 ° C. or less. Incidentally, it accelerated cooling, not only generation suppressing effect of the carbide as described above, also has the effect of suppressing the grain growth of the austenite. Therefore, from the viewpoint of suppressing grain growth of the austenite is carried out in combination with accelerated cooling and hot rolling described above.
[0063]
(3) heat treatment step
　case without accelerated cooling described above, for example, when cooled by air cooling after hot rolling, for degradation of the precipitated carbides, it is necessary to perform heat treatment on the steel sheet after hot rolling . Such heat treatment can be given to a solution treatment. In the present embodiment, solution treatment, for example, the steel sheet was reheated to a temperature above 1100 ° C., subjected to average accelerated cooling a cooling rate of 1 ~ 200 ℃ / s from 1000 ° C. temperature above, 500 ° C. below the temperature until cool.
[0064]
　There is no particular need to limit the thickness of the steel sheet according to the present embodiment may be 3 ~ 100 mm. If necessary, the plate thickness of more than 6mm, or as good as more 12 mm, 75 mm or less, or 50mm may be less. Is not particularly necessary to define the mechanical properties of the steel sheet according to the present embodiment, JIS Z 2241: According to 2011, the yield stress (YS) of 300N / mm 2 or more, a tensile strength of the (TS) 1000 N / mm 2 or more , and elongation (EL) may be 20% or more. If necessary, the tensile strength 1020n / mm 2 or more, or 1050 N / mm 2 may be more, 2000N / mm 2 or less, or 1700 N / mm 2 may be less. Toughness of the steel sheet, JIS Z 2242: the absorbed energy at -40 ℃ by 2005 may be more than or 200 J 100 J.
[0065]
　Thus it describes the chemical composition and manufacturing conditions are satisfied, the abrasion resistance and strength, and excellent austenitic wear steel sheet toughness and ductility is obtained. Austenitic wear steel sheet according to the present embodiment, the rail crossing, Caterpillar liner, impeller blades, crusher blades, small members and construction machinery, such as rock hammers, industrial machinery, civil engineering, necessary pillars abrasion resistance in the building sector, steel pipe, can be suitably used for large-scale member such as the outer plate.
Example
[0066]
　Table 1-1 and slabs having the chemical compositions shown in Table 1-2, hot rolling at rolling conditions shown in Table 2-1 and Table 2-2, the products shown in Table 2-1 and Table 2-2 was a steel plate having a thickness. Comparative Examples Example 7 and Table 2-2 Table 2-1 41 air-cooled after hot rolling was carried out heat treatment under the conditions shown in Table 2-1 and Table 2-2 (solution treatment). For each test pieces taken from the obtained steel sheet austenite (gamma), the volume fraction of epsilon martensite (epsilon) and alpha 'martensite (alpha'), the average particle size of the austenite (gamma), yield stress (YS ), tensile strength (TS), elongation (EL), abrasion resistance was evaluated corrosive wear resistance and toughness. The results are shown in Table 2-1 and Table 2-2.
　The specific evaluation method and acceptance criteria for each characteristic values in Table 2-1 and Table 2-2 are as follows.
[0067]
　Austenite, a volume fraction of ε martensite and alpha 'martensite
　plate thickness central portion (1 / 2T depth from the surface of the steel sheet (T is thickness)) of the steel sheet cut three samples from the plate thickness direction thereof specimen and the observation surface a plane parallel to the rolling direction, after mirror-finished by buffing the observation surface to remove distortion by electrolytic polishing or chemical polishing.
　With respect to the observation plane, X-rays diffraction apparatus: using (XRD Rigaku RINT2500), face-centered cubic structure of austenite (fcc structure) (311) (200) (220) the average value of the integrated intensity of the surface When, of ε martensite hexagonal close-packed lattice structure (hcp structure) (010) (011) (012) and the average value of the integrated intensity of the surface, a body-centered cubic structure (220) of the (bcc structure) of the alpha 'martensite (200) (211) from the average value of the integrated intensity of the surface to obtain austenite, epsilon the volume fraction of martensite and alpha 'martensite.
[0068]
　However, alpha 'martensite body-centered tetragonal structure (bct structure), and the diffraction peak obtained by X-ray diffraction measurement, when a double peak due to the anisotropy of the crystal structure, the integrated intensity of each peak from the total of, to obtain the volume fraction of α 'martensite. If you can separate the peaks, the sum of the respective integral intensities gave the volume fraction of alpha 'martensite.
[0069]
　The volume fraction of austenite is 40% or more, the case of less than 95% was judged to be acceptable as being within the scope of this invention. Volume fraction is less than 40% of the austenite, the case of 95% or more was judged as unacceptable as being outside the scope of the present invention.
[0070]
　The average particle size of austenite:
　mid-thickness portion (1 / 2T depth from the surface of the steel sheet (T is thickness)) of the steel sheet cut three samples from the observation surface a cross section parallel to the rolling direction and the thickness direction of the steel sheet and then, after the mirror with an alumina polishing or the like, corroded by nital solution. In the observation plane, a 1 mm × 1 mm or more field of view magnified at 100 times, JIS Z0551: 2013 Annex C. The cutting method according to the second straight test lines, the mean intercept length of the crystal grains 1 per austenite observed during the observation field of view was determined and an average particle diameter of this.
　Mean In addition, SMAW where the welding heat input approximately 1.7kJ / mm (shielded metal arc welding), FL HAZ of (fusion line) near the at mid-thickness portion, the HAZ of austenite in the same manner as described above the particle size was determined.
[0071]
　When the average particle size of austenite in the steel sheet (base material) is 40 ~ 300 [mu] m, was judged to be acceptable as being within the scope of this invention. On the other hand, if the average particle size of austenite in the steel sheet (base material) is outside the range of 40 ~ 300 [mu] m, it was determined unacceptable as being outside the scope of the present invention.
[0072]
　Yield stress (YS), tensile strength (TS) and elongation (EL):
　using the width direction of the steel sheet, a tensile test piece and the length direction is taken to be parallel to the test specimen, JIS Z 2241: 2011 It was evaluated in accordance with the. However, the plate thickness 20mm or less of the tensile test piece is JIS Z 2241: the 13B issue of 2011, thickness 20mm greater than the tensile test piece is JIS Z 2241: was the No. 4 of 2011.
[0073]
　Yield stress (YS) is 300N / mm 2 or more, a tensile strength (TS) is 1000 N / mm 2 or more, and elongation (EL) is the case of 20% or more was judged to be acceptable as excellent strength and ductility. The is not satisfied even one of the above conditions was determined as unacceptable.
[0074]
　Abrasion resistance:
　silica sand as a wear member (JIS G5901: 5 No. 2016) with a mixture of water (mixing ratio silica sand 2: water 1) scratching abrasion test in the case of using the (peripheral speed 3.7 m / sec the abrasion loss of 50 hours), ordinary steel (JIS G3101: SS400 of 2015) was evaluated as a reference. Table 2-1 and the wear volume ratio of pairs ordinary steel in Table 2-2 was obtained by dividing the abrasion loss of each steel in abrasion loss of ordinary steel. However, the plate thickness of 15mm than was used was Atsushi reduced in thickness 15mm specimen.
[0075]
　Where wear amount ratio of pairs ordinary steel is less than 0.20, it was judged to be acceptable as excellent wear resistance. On the other hand, the case where the wear amount ratio of resistant carbon steel is 0.20 or more, determines that failed as poor abrasion resistance.
[0076]
　Corrosive wear resistance:
　silica sand as a wear member for the evaluation of the corrosion wear (average particle size 12 [mu] m) and a mixture of sea water (mixing ratio 30% silica sand, 70% seawater) scratching abrasion test using a (peripheral speed 3 the abrasion loss of .7m / sec, 100 hours), ordinary steel (JIS G3101: SS400 of 2015) was evaluated as a reference. Table 2-1 and corrosive wear amount ratio of pairs ordinary steel in Table 2-2 was obtained by dividing the corrosive wear loss of each steel corrosion abrasion loss of ordinary steel. However, the plate thickness of 15mm than was used was Atsushi reduced in thickness 15mm specimen.
　In preferred embodiments of the present invention, the target value of the corrosive wear amount ratio of pairs ordinary steel was 0.80.
[0077]
　Toughness:
　Toughness of the steel sheet (base material) is, 1 / 4T of the steel sheet (T is thickness) parallel to the test piece and the rolling direction from the position of the collected, notched in a direction such that the crack propagates in the width direction were JIS Z 2242: by using the V-notch test piece 2005, JIS Z 2242: conforms to 2005, absorbed energy at -40 ° C. (vE -40 ° C. was evaluated (J)).
　In addition, welding heat input approximately 1.7kJ / mm (where the thickness of 6mm 0.6 kJ / mm, thickness 12mm was 1.2kJ / mm.) And the SMAW (shielded metal arc welding), the plate the thickness FL (fusion line) at the center using a Charpy test piece HAZ in the vicinity of the notch position, absorbed energy at -40 ℃ (vE by the same conditions as described above -40 ℃ were evaluated (J)) .
[0078]
　Absorbed energy at -40 ℃ of steel (base material) is a case of more than 200 J, was judged to be acceptable as excellent toughness. Absorbed energy at -40 ℃ of steel (base material) is a case of less than 200 J, it is determined that the failed as poor toughness.

The scope of the claims

[Requested item 1]Chemical composition, in
mass%,
C: 0.2
~ 1.6%, Si: 0.01 ~ 2.00%, Mn: 2.5
~ 30.0%, P: 0.050% or
less, S : 0.0100% or
less,
Cu:
0 ~ 3.0%, Ni: 0 ~
3.0%, Co: 0 ~ 3.0%, Cr:
0 ~ 5.0%, Mo: 0 ~ 2.0
%,
W:
0 ~ 2.0%,
Nb: 0 ~ 0.30%, V: 0 ~
0.30%, Ti: 0 ~ 0.30%, Zr: 0 ~
0.30%, Ta: 0
0.30%
~,
0 ~ 0.300%, Al: 0.001 ~
0.300%, N: 0 ~ 1.000%, O: 0 ~
0.0100%, Mg: 0 ~ 0.
% 0100,
Ca: 0 ~ 0.0100%, REM: 0 ~ 0.0100%,
the balance is Fe and impurities,
　C the content by mass percent of C and Mn, respectively, and when expressed as Mn, meet -13.75 × C + 16.5 ≦ Mn ≦ -20 × C + 30,
　metal structure, volume fraction,
　austenite: 40% or more and less than 95%,
　wherein the average particle size of the austenite is 40 ~ 300 [mu] m, austenitic wear steel.
[Requested item 2]
　The chemical composition, and satisfies the following formula, austenitic wear steel sheet according to claim 1.
　-C + 0.8 × Si-0.2 × Mn-90 × (P + S) + 1.5 × (Cu + Ni + Co) + 3.3 × Cr + 9 × Mo + 4.5 × W + 0.8 × Al + 6 × N + 1.5 ≧ 3.2
　Formula each element symbol in indicates the content by mass percent of the respective elements.
[Requested item 3]
　The metal structure, by volume fraction,
　epsilon martensite: 0-60%,
　alpha 'martensite: 0-60%,
　the epsilon martensite and the alpha' total martensite: 5 to 60%
　to be a wherein austenitic wear steel sheet according to claim 1 or 2.
[Requested item 4]
　The chemical composition, in
mass%, O: 0.0001 ~
0.0100%, 0.0001 ~ 0.0100%: Mg content, total Ca content and REM content
　, characterized in that it is, austenitic wear steel sheet according to any one of claims 1-3.
[Requested item 5]
　The chemical composition, in
mass%, S: a 0.0001 to 0.0050 percent,
　the content by mass percent of O and S and satisfies the O / S ≧ 1.0, claims austenitic wear steel sheet according to 4.
[Requested item 6]
　The chemical composition, when representing the content by mass percent of C and Mn C, respectively, and the
　Mn, and satisfies the -6.5 × C + 16.5 ≦ Mn ≦ -20 × C + 30, wherein austenitic wear steel sheet according to any one of claim 1-5.
[Requested item 7]
　The chemical composition, in mass%,
Cu: 0 ~ 0.2%
　, characterized in that a, austenitic wear steel sheet according to any one of claims 1-6.