Art
[1]
The present invention relates to a cold-rolled steel sheet, and relates to a method of manufacturing the same, and more particularly, high-temperature characteristics and the excellent workability at room temperature the cold-rolled steel sheet and a manufacturing method used for an electric vehicle battery keyiseuyong cylindrical can.
[2]
BACKGROUND
[3]
It is common to carry out nickel (Ni) plating on the steel sheet as the case of the circular can be used for the battery case of a primary battery in order to withstand alkaline properties entering the cell contents fundamentally required corrosion resistance.
[4]
In recent years, it is widely used as a battery case material for a secondary battery of an electric automotive applications, including battery cans for material primary battery for mobile, power tools, such as mobile phones as well.
[5]
In this manner and the requirements for the characteristics of the battery case to improve the life and improve the environment increases as the diversification of battery keyiseuyong material. Also it is pursued a technology developed to ensure the safety at the same time to further reduce the thickness case body portion in order to increase battery capacity by increasing the capacity of the entire charge.
[6]
Improvement applies to the use of the battery case with the steel basis characteristics for ensuring the safety of the can according to the expansion of the automobile industry, in particular, and also increased demand for high-temperature characteristics. Efforts to apply an electric car or a hybrid car traditional stainless steel or aluminum, such as cost savings and productivity gains in the form of steel cans in terms of prototype battery, etc. keyiseuyong cell (Cell), who used the material in the field are in progress. That is, these battery cases products are used Environment Prize momentarily because hundreds also be exposed to high temperatures (℃) to be secured to the heat-resistant characteristics that can withstand the high temperature essentially.
[7]
Heat-resistant property can be evaluated in a number of ways, one example of an electric vehicle maker in the heat-resistant property in it and apply the method of heating to a temperature of 600 ℃ and out after filling the battery into the battery case evaluate the reliability of the cell constant temperature there is emerging as an important management factor.
[8]
In addition, the battery cell is deteriorated part by a car traveling a local temperature increase should be strictly managed deformation properties at high temperatures in order to avoid this, it may affect the running of the car. The sag in my point of view as this is regarded as an important management factors Saints. Sag (Sag) property means a property that a deflection phenomenon (sagging) occurs by the repeated change in the material of the material exposed to the high temperature. When this occurs and the molded part form-retaining difficult, the part is a high temperature strength is reduced if the thermal stress to be concentrated in specific areas, if severe work shape to deteriorate and there may still cause breakage through the shape fixability securing of the work piece in order to secure the stability of the temperature management, an electric vehicle, the battery case uses of parts, the dynamic strain aging phenomenon caused by the above high-temperature strength at 600 ℃ 110MPa, cheochim of material are to be satisfied for more than 0.05mm employment element at a high temperature to be suppressed is required.
[9]
In the conventional heat-resistant purpose came been mainly used a stainless steel plate, stainless steel sheet, Cr, Ni, etc., as well as high manufacturing costs, as a large amount addition of expensive alloying elements, when in a high-temperature subject to the Cr of the grain boundary in combination with the C boundary the chromium-carbide is in the form of intergranular corrosion caused by being precipitated as a Cr depleted layer (chromium depleted zone) area had a poor corrosion resistance problem.
[10]
On the other hand, when the battery case used in the automobile is mounted in a manner of being laminated in a limited, the same workpiece area, it requires multi-stage machining process such as drawing and stretch processing when molding in addition to the high-temperature characteristics, a workability is also an important management factor at room temperature . That is, the steel sheet is a material such as an alkaline manganese battery or a lithium battery the battery case is made of two-piece (Piece) round the can body and the lower part of a so-called candle processed into a cylindrical shape by press molding which is processed into a one-piece. In this case, at the same time as punching (Punching) the material of 0.3mm around a circular blank (Blank) of a cylindrical deep-drawing molding process and that the deep-drawing sikimyeo the material through the mold for a plurality of ironing (Ironing) thickness the thin and is subjected to ironing processing to raise the height of the cans. Thus two-piece battery keyiseuyong material is possible to reduce the thickness than the original plate by the eye parts in the manufacturing process, the case body (Body), and ironing working, the thickness of this body case through the final 20 to 40% compared to the original thickness It is thinned. In this instance, the prior art of manufacturing such battery can for example a technique disclosed in Patent Document 1.
[11]
Further, Patent Document 2, there is a room to improve the sealing performance of the battery can start to utilize the low and medium carbon steel by increasing the material strength through the secondary rolling.
[12]
A, however, had the measures of even could not solve the problems associated with securing strength and dynamic strain aging inhibition at high temperature, 600 ℃ that required in an electric vehicle battery cases for the case, the second rolling step added in the manufacturing process the side of the disk depending was a problem which acts as a separate manufacturing cost increase factors.
[13]
[14]
(Prior art document)
[15]
[Patent Document 1] Japanese Patent Laid-Open No. 58-176861 cattle
[16]
(Patent Document 2) Japanese Patent Application Laid-Open Japanese Patent Hei 11-189841 porous
[17]
Detailed Description of the Invention
SUMMARY
[18]
A preferred aspect of the present invention to a high-temperature characteristics, and workability at room temperature to provide a cold-rolled steel sheet excellent.
[19]
[20]
Another preferred aspect of the present invention is to provide a process for producing at low cost a high-temperature characteristics, and the cold-rolled steel sheet excellent workability at room temperature.
[21]
Problem solving means
[22]
According to a preferred aspect of the invention, in weight%, C: 0.0005 ~ 0.003%, Mn: 0.30 ~ 0.70%, Al: 0.02 ~ 0.10%, P: 0.003 ~ 0.020%, N: 0.002 ~ 0.006%, S: 0.015% or less (including 0%), V: contains 0.04 ~ 0.10%, the balance Fe and other unavoidable impurities;: 0.01 ~ 0.05%, B: 0.0005 ~ 0.0035%, W The following relation (1), the V and C, and the effective atomic ratio of 0.00009 ~ 0.00069 N for B to be represented by a;
[23]
[Expression 1]
[24]
(V*1.2B)/(C+N)
[25]
(Here, the atomic ratio = (V wt% / 51) 1.2 * (B% by weight / 11) / {(C wt.% / 12) + (wt% N / 14)} in a wanted)
[26]
Microstructure is 95% or more polygonal ferrite by area% and 5% or less (0% is excluded) comprises a needle-like ferrite and; And 0.01 ~ 0.10㎛ the amount of (V, B) cold-rolled steel sheet having excellent formability, including (C, N) precipitates is provided .
[27]
[28]
The cold-rolled steel sheet may comprise a coating layer.
[29]
[30]
The cold-rolled steel sheet may preferably be, may comprise a Fe-Ni alloy plating contains in% by area, the Fe-Ni alloy plating layer of 5 to 25%.
[31]
[32]
According to another aspect a preferred of the present invention, in weight%, C: 0.0005 ~ 0.003%, Mn: 0.30 ~ 0.70%, Al: 0.02 ~ 0.10%, P: 0.003 ~ 0.020%, N: 0.002 ~ 0.006%, S : 0.015% or less (including 0%), V: 0.01 ~ 0.05%, B: 0.0005 ~ 0.0035%, W: 0.04 ~ 0.10%, above which is represented by the balance Fe and other inevitable to, and including impurities relational expression (1) slab heating step of the effective atomic ratio of C and N in the steel slab heating 0.00009 ~ 0.00069 for V and B;
[33]
[Expression 1]
[34]
(V*1.2B)/(C+N)
[35]
(Here, the atomic ratio = (V wt% / 51) 1.2 * (B% by weight / 11) / {(C wt.% / 12) + (wt% N / 14)} in a wanted)
[36]
Obtaining a hot-rolled steel sheet by hot rolling the heated slab to finish rolling temperature of 900 ~ 950 ℃ hot rolling step;
[37]
Winding step for winding the hot-rolled steel sheet from 560 ~ 680 ℃;
[38]
Cold rolling to obtain a cold-rolled steel sheet and cold rolling the hot-rolled steel sheet; And
[39]
In workability comprising a step of heat treatment after the cold-rolled steel sheet was heated to a temperature of 680 ~ 780 ℃, cooled at a cooling rate of 40 ~ 70 ℃ / sec is provided a method of manufacturing a cold-rolled steel sheet excellent .
[40]
[41]
Method for manufacturing the cold-rolled steel sheet may further comprise a coating step of forming a plating layer on a cold-rolled steel sheet cooled in the cooling step.
[42]
[43]
Method for manufacturing the cold-rolled steel sheet may further comprise a heat treatment step of obtaining the alloy plating layer alloyed by the alloying treatment of the plating step and the plating layer for forming a plating layer on a cold-rolled steel sheet cooled in the cooling step.
[44]
[45]
Method for manufacturing the cold-rolled steel sheet is treated by alloying the Ni plating step and a Ni plating layer to form a Ni plating layer on a cold-rolled steel sheet cooled in the cooling step may further include the alloying heat treatment step of obtaining the Fe-Ni alloy plate layer.
[46]
Alloying treatment step of the Ni plating layer is preferably carried out as a% by area to form the Fe-Ni alloy plating layer of 5 to 25%.
[47]
Effects of the Invention
[48]
According to a preferred aspect of the invention, as compared to a stainless steel plate and it can be manufactured at a low cost, ironing (Ironing), and deep-drawing (Deep drawing) and is excellent in room temperature formability in a variety of machining processes, dynamic strain aging phenomenon at a high temperature, such as not only does not occur, it is possible to secure the shape fixability of the product to be used at high temperatures and excellent high-temperature strength and high-temperature deformation properties can be a high safety of the product and manufacturing processing cold-rolled steel sheet having a heat-resistant property.
[49]
Brief Description of the Drawings
[50]
1 is at a high temperature seal of the invention the material 2 and the comparative material 6 at 600 ℃ strain-stress curve as referring to, (a) shows an inventive material 2, (b) shows a comparative material 6.
[51]
Best Mode for Carrying Out the Invention
[52]
It will now be described in detail with respect to the cold-rolled steel sheet of the present invention.
[53]
The present inventors have found that a low cost as ironing property, bending property, dip satisfies the high-temperature properties such as drawability variety of room temperature processing properties and Nash Hyosung, deflection characteristic of less than one while satisfying the corrosion resistance of 110MPa at 600 ℃ high-temperature strength and 3mm, such as at the same time repeated research and experiments to obtain a steel plate and completed the present invention to.
[54]
[55]
The main concept of the present invention are as follows.
[56]
1) to have appropriate control of the steel component and the component range, it is possible to ensure excellent temperature characteristics and high-temperature characteristics over them.
[57]
[58]
2) to have appropriate control over the effective atomic ratio of C and N to V and B, by this form the composite precipitates of fine (V, B) (C, N) system with and control the strength and deformation behavior at high temperatures it is possible to ensure the endoscopic Hyosung and workability at room temperature.
[59]
[60]
3) that control the microstructure of the steel sheet, this high temperature property over, as well as it is possible to ensure excellent high-temperature strength and high-temperature characteristics.
[61]
[62]
4) that appropriately controlling the heat treatment conditions of the cold-rolled steel sheet, it is possible to ensure an appropriate microstructure of the steel plate through this.
[63]
[64]
5) as to form a coating layer and / or the alloy plating layer on the surface of the steel sheet, as needed, it is possible to ensure excellent corrosion resistance with it. In particular, for example, excellent corrosion resistance against the alkaline component of the cell contents can be secured.
[65]
[66]
The following describes a cold-rolled steel sheet according to an aspect of the invention.
[67]
With the% by weight of cold-rolled steel sheet according to an aspect of the invention, C: 0.0005 ~ 0.003%, Mn: 0.30 ~ 0.70%, Al: 0.02 ~ 0.10%, P: 0.003 ~ 0.020%, N: 0.002 ~ 0.006%, S : 0.015% or less (including 0%), V: contains 0.04 ~ 0.10%, the balance Fe and other unavoidable impurities;: 0.01 ~ 0.05%, B: 0.0005 ~ 0.0035%, W The following relation (1), the V and C, and the effective atomic ratio of 0.00009 ~ 0.00069 N for B to be represented by a;
[68]
[Expression 1]
[69]
(V*1.2B)/(C+N)
[70]
(Here, the atomic ratio = (V wt% / 51) 1.2 * (B% by weight / 11) / {(C wt.% / 12) + (wt% N / 14)} in a wanted)
[71]
Microstructure is 95% or more polygonal ferrite by area% and 5% or less (0% is excluded) comprises a needle-like ferrite and; And comprises 0.01 ~ 0.10㎛ size (V, B) (C, N) precipitates.
[72]
[73]
First, a description will be given to the component and component range limitation reasons of the present invention. (Hereinafter simply referred to as% is% by weight);
[74]
[75]
Carbon (C): 0.0005 ~ 0.003%
[76]
Carbon (C) is in the present invention as an element to be added to the strength of the steel sheet is mainly consumed by the reaction of V and for vanadium carbide-based precipitates formed. Tensile strength and yield strength is increased the more the amount of C is because the workability is degraded when the increased addition of one over the upper limit is 0.003% is preferred. However, less than 0.0005% is sufficient (V, B) (C, N) based enough can not obtain the strengthening effect at high temperatures by the composite precipitate to the grain size increases orange at the time of molding of the-like filter (Orange peel) it may cause a machining deteriorated, the content of C is limited to 0.0005% to 0.003%. The preferred amount of carbon (C) may be 0.0007 ~ 0.0027%.
[77]
[78]
Manganese (Mn): 0.3 ~ 0.7%
[79]
Manganese (Mn) is more than 0.30% is added is necessary to typical austenite as well as nitro stabilizing element to increase the strength of the steel as a solid solution strengthening element to obtain the effects such as an element to prevent hot cracking of the slab, by precipitating S in MnS type . On the other hand, when Mn is added, so a large amount ductility is lowered and serves as a center segregation factor of the coating adhesion and the corrosion resistance decreases when Ni plating of the steel sheet as well as the result that the upper limit is limited to 0.70%. A preferred content of manganese (Mn) may be 0.35 ~ 0.65%.
[80]
[81]
Aluminum (Al): 0.02 ~ 0.10%
[82]
Aluminum (Al) has to contain 0.02% or more is needed to improve the aging characteristics in combination with a steel employ nitrogen as the element added for deoxidation of molten steel.
[83]
However, when more than 0.1% Al is added to the effect of Al is saturated, so the factor of the increase in the amount of the steel inclusions causing surface defects and degrade the formability, the content of Al is limited to 0.02 ~ 0.10%. The preferred content of aluminum (Al) may be 0.025 ~ 0.085%.
[84]
[85]
Of (P): 0.003 ~ 0.020%
[86]
Phosphorus (P) is preferably not less than 0.003% in order to obtain these characteristics as an element of improving the strength of the steel and corrosion resistance, but if the content exceeds 0.020%, the segregation at grain boundaries, as well as grain boundary embrittlement occurs, degradation of the workability so badly during the plating adhesion, such as Ni, and the content of P is limited to 0.003 ~ 0.020%.
[87]
[88]
Nitrogen (N): 0.002 ~ 0.006%
[89]
Nitrogen (N) when containing less than 0.002% as an element effective for strengthening as present in a solid solution state within the steel, and it can not be obtained a sufficient rigidity precipitate formation site is reduced, and when the content is more than 0.006% by employment element over since the main reason for the cause of aging is cured up deteriorating the formability, the content of N is limited to 0.002 ~ 0.006%. The preferred amount of nitrogen (N) may be 0.0020 ~ 0.0050%.
[90]
[91]
Sulfur (S): 0.015% or less (including 0%)
[92]
Sulfur (S) is therefore preferable to form the non-metallic inclusions that the corrosion starting points role in combination with the steel Fe and reducing the content of possible since the factors red-short (Red shortness) content of S is limited to not more than 0.015% . However, it is preferred to administer to less than 0.012% in order to reliably obtain the above effects.
[93]
[94]
Vanadium (V): 0.01 ~ 0.05%
[95]
Vanadium (V) is an element effective to improvement in strength and grain refinement of the steel sheet, the present invention improves the aging resistance and molding property by forming a composite precipitate V (C, N) system in conjunction with the steel of solid solution C and N, in addition, by inhibiting ferrite crystal grain growth at high temperature by the deposition of these fine precipitates and provides an effect of refining the crystal grains. In order to obtain the same effect, preferably containing at least 0.01% V, but if its content exceeds 0.05%, the material cured, and lowering the work efficiency of the heat treatment of it is a problem to deteriorate the surface properties of the steel plate, V the content is preferably limited to 0.01 ~ 0.05%. The preferred amount of vanadium (V) may be 0.015 ~ 0.050%.
[96]
[97]
Boron (B): 0.0005 ~ 0.0035%
[98]
For boron (B) is to obtain the same effect as this as an element for improving the high temperature properties by suppressing crystal grain growth at high temperatures, when present in solid solution state in the steel as an element for improving the hardenability is required more than 0.0005% is added, but the the addition of more than 0.0035% to delay the recrystallization, so the danger of the steel sheet tongpan castle or worse worse processability and B addition amount is limited to 0.0005 ~ 0.0035%. The preferred content of boron (B) may be 0.0008 ~ 0.0030%.
[99]
[100]
Tungsten (W): 0.04 ~ 0.10%
[101]
When in order to secure the tungsten (W) high temperature physical properties and the effect such a corrosion resistance as an element to be added for the purpose for requires at least 0.04%, but the content of W exceeds 0.10%, the deterioration of work efficiency such as rolling property acts as a factor that because the content is limited to 0.04 ~ 0.10% content of the preferred tungsten (W) may be 0.040 ~ 0.095%.
[102]
[103]
(V * 1.2B) / the effective atomic ratio of (C + N): 0.00009 ~ 0.00069
[104]
In the case of V and B is also important to management by itself, but by keeping the (V * 1.2B) the effective atomic ratios of V and B / (C + N) of the C and N to a certain range (V, B) (C , it is important to obtain N) based a room temperature Nash Hyosung and workability and high temperature strength and high-temperature deformation behavior by controlling the deposition conditions of the complex precipitates at the same time.
[105]
(V * 1.2B) / (C + N) is less than the effective atomic ratio of 0.00009, the steel employee room temperature Nash Hyosung and workability is increased by a small amount is deteriorated, and the precipitate of the complex system (V, B) (C, N) depending on the deposition amount is less may possibly be unable to suppress the dynamic strain aging phenomenon in the high-temperature strength and high temperature. On the other hand, the effective value of the atomic ratio exceeds 0.00069 and the recrystallization temperature rises due to fine precipitates steel tongpan property is poor, and because it may degrade the operability of the process after the surface properties are deteriorated, (V * 1.2B ) value of the effective atomic ratio / (C + N) is limited to 0.00009 ~ 0.00069. Effective atomic ratio values ​​of the desired (V * 1.2B) / (C + N) may be 0.00010 ~ 0.00065.
[106]
[107]
Cold-rolled steel sheet according to an aspect of the invention comprises a balance of Fe and other unavoidable impurities, containing the above components. And the alloying elements to improve the characteristics of the cold-rolled steel sheet as needed, it can be further added, the alloying elements were added not disclosed in the embodiments of the present invention but are not construed to be excluded from the scope of the invention.
[108]
[109]
Cold-rolled steel sheet is less than 95% or more polygonal ferrite and 5% by area percent according to one aspect of the present invention (excluding 0%), it has a microstructure comprising an acicular ferrite.
[110]
If the case, the fraction of the polygonal ferrite is less than 95% by area% is the difficulty in high-temperature properties, in particular high-temperature strength obtained, the needle-like ferrite fraction exceeds 5%, the drawing having a suitable shape to poor room temperature workability by the material curing it is a problem with the material produced is necessary administration of the appropriate fraction.
[111]
[112]
Cold-rolled steel sheet according to an aspect of the invention includes a size of 0.01 ~ 0.10㎛ (V, B) (C, N) precipitates.
[113]
In terms of the size of the precipitates inhibiting the grain growth than if small 0.01㎛ desirable, raising the recrystallization temperature of the steel sheet tongpan St. the high temperature properties if the coarse precipitates, and to be degraded, while the precipitate size is more than 0.10㎛ since this problem could not be obtained and the size of precipitate is limited to 0.01 ~ 0.10㎛ range.
[114]
[115]
The cold-rolled steel sheet may comprise a single layer or multi-layer plating layer, the alloy plating layer of a single-layer or multi-layer, or multi-layer of the plated layer and the alloy plated layer.
[116]
[117]
To the plating layer and alloy plating layer, it is preferable to form an alloy-plated layer obtained by heat diffusing There is no particular restriction on its type as long as it can ensure the corrosion resistance, a single layer or multi-layer plating layer and / or a plating layer on both surfaces of the steel sheet.
[118]
[119]
The cold-rolled steel sheet is preferably may comprise a Fe-Ni alloy plating layer, it is possible to more preferably in area%, the Fe-Ni alloy plating layer of 5 to 25%.
[120]
For example, when applied to the battery keyiseuyong steel sheet may comprise a Fe-Ni alloy plate layer on the both surfaces of the steel sheet, it is possible to more preferably in area%, the Fe-Ni alloy plating layer of 5 to 25% . If you do this, it is possible to ensure excellent corrosion resistance to the alkali component of the cell contents. Fe-Ni alloy plating layer formed on the both sides is obtained by alloying an Ni-plated layer, and in this case, the thickness of both sides of each of the Ni plated layer is 1 ~ 5㎛ preferred.
[121]
[122]
The following describes a method of manufacturing a cold-rolled steel sheet with excellent workability according to another aspect of the present invention.
[123]
[124]
Method of manufacturing a cold-rolled steel sheet according to another aspect a preferred of the present invention in weight%, C: 0.0005 ~ 0.003%, Mn: 0.30 ~ 0.70%, Al: 0.02 ~ 0.10%, P: 0.003 ~ 0.020%, N: 0.002 ~ 0.006%, S: 0.015% or less (including 0%), V: 0.01 ~ 0.05%, B: 0.0005 ~ 0.0035%, W: 0.04 ~ 0.10%, the balance to, and including Fe and other inevitable impurities relation (1 ) slab heating step of the effective atom of C and N for the V and the B ratio is 0.00009 ~ 0.00069 heating the steel slab is represented by;
[125]
[Expression 1]
[126]
(V*1.2B)/(C+N)
[127]
(Here, the atomic ratio = (V wt% / 51) 1.2 * (B% by weight / 11) / {(C wt.% / 12) + (wt% N / 14)} in a wanted)
[128]
Obtaining a hot-rolled steel sheet by hot rolling the heated slab to finish rolling temperature of 900 ~ 950 ℃ hot rolling step;
[129]
Winding step for winding the hot-rolled steel sheet from 560 ~ 680 ℃;
[130]
Cold rolling to obtain a cold-rolled steel sheet and cold rolling the hot-rolled steel sheet; And
[131]
After the cold-rolled steel sheet was heated to a temperature of 680 ~ 780 ℃, and a heat treatment step of cooling at a cooling rate of 40 ~ 70 ℃ / sec.
[132]
[133]
Slab heating step
[134]
Steel slab composition which, like the above-described component is heated before hot rolling.
[135]
The heating temperature of the steel slab is not particularly limited, the heating temperature of the steel slab is preferred, for example, is 1180 ~ 1280 ℃.
[136]
[137]
Hot rolling step
[138]
In the hot rolling step and the hot-rolled seulrabeueul heated at the slab heating step to obtain a hot-rolled steel sheet.
[139]
Hot rolling during the finish rolling temperature is 900 ~ 950 ℃ is preferred.
[140]
If the finish rolling temperature is lower than 900 ℃ relatively is upset hot rolling is finished the final honrip of the formed crystal grains as occurs in the low temperature range processability, and this decreases the rolling property, if the finish rolling temperature exceeds 950 ℃ uniform throughout the thickness as the hot rolling is not to be achieved grain refinement is insufficient because there is a problem in that the impact toughness due to coarsening of crystal grains decreases, the finish rolling temperature is preferably limited to 900 ~ 950 ℃.
[141]
[142]
Winding steps
[143]
Hot-rolled steel sheet obtained in the hot rolling step is run-and is then wound around a cooling table, etc. out. When winding the winding temperature is 560 ~ 680 ℃ is preferred.
[144]
The coiling temperature is less than 560 ℃ is slightly hardened material of the hot-rolled material primary process is difficult and the rolling load increased rolling property secured at the cold rolling step, the precipitation aspect of the low temperature deposits varies with the width direction of the temperature non-uniformity seriously occurred there is a possibility according to the material function and the deviation factor of workability degradation. When the take-up in excess of 680 ℃ whereas been coarsened crystal grains of the finished product because it may deteriorate the high temperature strength and corrosion resistance, the winding temperature is preferably limited to 560 ~ 680 ℃.
[145]
[146]
Cold rolling step
[147]
In the cold rolling step and cold rolling the hot-rolled steel sheet to a desired thickness to obtain a cold-rolled steel sheet. It may pickling the hot-rolled steel sheet before cold rolling.
[148]
[149]
Cold rolling reduction rate, and when 80% or more is preferable, a more preferable reduction ratio is 85% or more.
[150]
[151]
The thickness of the cold-rolled steel sheet after the cold rolling has a thickness of 0.1 ~ 0.4mm is preferable, and a more preferred cold-rolled steel sheet is 0.16 ~ 0.4mm.
[152]
[153]
A heat treatment step
[154]
In the heat treatment step the cold rolled steel sheet was heated at a temperature of 680 ~ 780 ℃, it is cooled at a cooling rate of 40 ~ 70 ℃ / sec.
[155]
If the soaking temperature is less than 680 ℃ has low fraction of recrystallized grain strength can not be allocated in the workability in ductility off the high contrast. To cause defects such as buckles (Heat Buckle) - on the other hand, when the soaking in excess of 780 ℃ recrystallization is completed and the glass in terms of securing the transformation drive force of the acicular ferrite structure, but the heat of the high temperature heat treatment such as a pole Park shot acts as a factor of the steel sheet tongpan property decreases because the soaking temperature is preferably managed as 680 ~ 780 ℃.
[156]
[157]
The heated steel sheet is cooled at a cooling rate of 40 ~ 70 ℃ / sec.
[158]
When cooling the steel plate at a cooling rate of less than 40 ℃ / sec as low a fraction of the gain can acicular ferrite crystal grains is grain growth occurs at a high temperature, whereas it is difficult, and to secure the high temperature strength and high temperature properties, the cooling rate is 70 ℃ when / sec is exceeded, so the shape and material of the deviation by the processability deteriorates and non-uniform cooling in the width direction due to improvement in strength occurs, the cooling rate is preferably limited to 40 ~ 70 ℃ / sec.
[159]
[160]
On cooling the cooling end temperature is 450 ~ 350 ℃ is preferred.
[161]
If the cooling end temperature is below 350 ℃ had a danger of lowering the workability after the process has a problem that the work type control is difficult, if a cooling end temperature is higher than 450 ℃ has a high temperature to suppress the precipitation of the employed carbon Nash there is a problem that badly Hyosung.
[162]
[163]
The cold-rolled steel sheet produced according to the production method of the cold-rolled steel sheet according to another preferred aspect of the present invention may include a size of 0.01 ~ 0.10㎛ (V, B) (C, N) precipitates.
[164]
In terms of the size of the precipitates inhibiting the grain growth than if small 0.01㎛ desirable, raising the recrystallization temperature of the steel sheet tongpan St. the high temperature properties if the coarse precipitates, and to be degraded, while the precipitate size is more than 0.10㎛ there are problems that can not be secured.
[165]
[166]
Plating step and the alloying heat treatment
[167]
Method for manufacturing the cold-rolled steel sheet may further comprise a coating step of forming a plating layer on a cold-rolled steel sheet cooled in the cooling step.
[168]
Method for manufacturing the cold-rolled steel sheet may further comprise a heat treatment step of obtaining the alloy plating layer alloyed by the alloying treatment of the plating step and the plating layer for forming a plating layer on a cold-rolled steel sheet cooled in the cooling step.
[169]
The plating step and the alloying heat treatment step is not particularly limited.
[170]
Plating method, for example, and the like deulsu melt plating method and electroplating method, particularly can be preferably applied to an electrical contractor method for forming the coating layer.
[171]
Method for manufacturing the cold-rolled steel sheet is treated by alloying the Ni plating step and a Ni plating layer to form a Ni plating layer on a cold-rolled steel sheet cooled in the cooling step may further include the alloying heat treatment step of obtaining the Fe-Ni alloy plate layer.
[172]
Alloying treatment step of the Ni plating layer is preferably carried out as a% by area to form the Fe-Ni alloy plating layer of 5 to 25%.
[173]
Fraction of the alloy layer of Fe-Ni alloy plating layer, because of the close relationship with the corrosion resistance and the surface hardness of the material it is necessary to secure a proper alloy layer fraction.
[174]
When the Fe-Ni alloy fraction of the alloy layer of the coated layer is less than 5% in the alloy also is low is that the surface material material coated cured in accordance with the fraction on the other hand, is a factor of deterioration of the processing die life more than 25% die life in terms of improving the glass, but it is a problem that the corrosion resistance of the surface layer deteriorates appropriate alloy ratio is preferably limited to 5-25%.
[175]
[176]
Alloying treatment step of the Ni plating layer is preferably carried out at 650 ~ 750 ℃.
[177]
The alloying heat treatment is, for example, can be carried out for a short time of less than 3 seconds.
[178]
[179]
If the alloying heat treatment temperature is lower than 650 ℃ is in the sense of a problem that deterioration of processability, such as battery cases and, when an alloying heat treatment temperature exceeds 750 ℃ ​​securing alloying fraction of the coating layer as impossible to ensure the desired alloying fraction of glass but it acts as a factor deteriorating the grain surface-coated material processability and corrosion resistance to abnormal growth, so it is preferable that the alloying heat treatment temperature material electroplating is limited to 650 ~ 750 ℃.
[180]
For example, in the case of a battery keyiseuyong round tube made by the multi-stage drawing, there is a Ni plating the plating method and the, Ni 2 type of line plating method for press forming the plated steel sheet after that, after the press forming, the present invention provides a method of quantum treatment may be applied to any of plating method, it can exhibit the same effect.
[181]
Mode for the Invention
[182]
It is more specifically described in the present invention to the following examples.
[183]
EXAMPLES
[184]
The invention steel (1-4) and comparative steel (1-5) was prepared by dissolving a composition as shown in Table 1 below to work in process conditions as shown in Table 2 below, coated steel strip [invention material (1-7) and after preparing the comparative material (1-10)], evaluating the characteristics at room temperature and high temperature for each steel sheet thus prepared and the results are shown in Table 3 below. The thickness of the end plates is yiyeotda 0.30 mm. Here was alloying treatment at a temperature of alloying treatment after Ni plating, the following Table 2.
[185]
High temperature aging (aging) characteristics of the properties described in the following Table 3 has not occurred if that dynamic strain aging when done the high-temperature tensile test caused the mixture was kept at 600 ℃ 15 bungan is not a dynamic strain aging occurs to generate as it indicated.
[186]
On the other hand, FIG. 1 illustrates a high-temperature tensile of Comparative material 6 [1 (b) also Dynamic invention material strain aging does not occur 2 [Fig. 1 (a)] and caused the dynamic strain aging when subjected to high-temperature tensile test at 600 ℃ It shows the test chart. In the case of invention material 2-1 against indicate a uniform stress change as the strain is increased during the tensile test at a high temperature, a stress, as compared to material 6 as the strain is increased from strain curves represent the stress fluctuation behavior of the saw blade shape , such a phenomenon when the this phenomenon is due to the dynamic strain aging occurs the breakage by a local deformation increases during thermal shock.
[187]
Further, naesae geuseong test if at least after heating for 100 hours at 600 ℃ the material of the total length 250mm, width 30mm, using a heat treatment plant by measuring the deflection of the steel sheet that the deflection degree is less than is good (O) and 3mm 3mm was evaluated as bad (X).
[188]
Further, if it is less than the high-temperature strength by performing a high-temperature tensile test at 600 ℃ 110MPa Poor (X), was determined as a good (O) or more, workability test is a drawing ratio material blank diameter / drawing die diameter) of from 1.85 condition room temperature, drawing rate ear or during processing is more than 2.5% was evaluated as poor (X) if the machining crack (crack) occurred.
[189]
On the other hand, corrosion resistance rating of the electroplated workpiece is shown as good (O), if evaluated by a salt spray test (SST, Salt Spray Test), when melt within ever occurred 12 hours through it marked as bad (X), and not It was.
[190]
[191]
TABLE 1
division C Mn P S Al N V B W (V * 1.2B) / (C + N) atomic ratio
Invention steel 1 0.0021 0.45 0.005 0.002 0.028 0.0025 0.016 0.0011 0.045 0.00011
Invention steel 2 0.0016 0.38 0.011 0.009 0.035 0.0034 0.041 0.0018 0.058 0.00042
Invention steel 3 0.0025 0.57 0.014 0.010 0.064 0.0049 0.045 0.0027 0.081 0.00047
Invention steel 4 0.0010 0.62 0.012 0.008 0.074 0.0032 0.038 0.0024 0.090 0.00063
Comparative Steel 1 0.0024 0.34 0.009 0.006 0.042 0.0028 0.006 0.0012 0.025 0.00004
Comparative Steel 2 0.0061 0.31 0.011 0.005 0.012 0.0025 0.064 0.0003 0.046 0.00006
Comparative Steel 3 0.0018 0.96 0.054 0.007 0.114 0.0031 - 0.0014 0.142 0
Comparative Steel 4 0.0028 0.52 0.009 0.006 0.026 0.0072 0.061 0.0041 - 0.00072
Comparative Steel 5 0.0251 0.23 0.007 0.008 0.031 0.0025 0.094 - 0.231 0

[192]
#) Where the atomic ratio = (V wt% / 51) 1.2 * (B% by weight / 11) / {(C wt.% / 12) + (wt% N / 14)} in a wanted
[193]
[194]
TABLE 2
Grades division The finish rolling temperature (℃) The coiling temperature (℃) The heating temperature (℃) Cooling rate (℃ / sec) Cooling end temperature (℃) Alloying treatment temperature (℃)
Invention steel 1 Comparative material 1 820 640 690 50 420 680
Invention material 1 910 640 720 59 435 700
Invention material 2 910 640 750 64 415 740
Invention steel 2 Invention Reset 930 660 740 60 375 660
Invention re-4 930 660 740 58 400 700
Comparative Material 2 930 540 740 60 325 710
Invention steel 3 Invention material 5 940 580 700 46 420 690
Invention material 6 940 580 740 59 360 720
Compare Resume 940 580 660 45 410 740
Invention steel 4 Invention material 7 920 620 720 55 415 740
Compare Re 4 920 750 680 34 480 600
Compare Re 5 920 620 740 61 400 780
Comparative Steel 1 Compare Re 6 910 640 740 58 410 740
Comparative Steel 2 Compare Re 7 910 640 740 60 410 740
Comparative Steel 3 Compare reconfiguration 910 640 740 56 410 740
Comparative Steel 4 Compare 9 Re 910 640 740 62 410 740
Comparative Steel 5 Compare Re 10 910 640 740 60 410 740

[195]
TABLE 3
division Microstructure (PF fraction) (% by area. Room temperature characteristic Properties at 600 ℃
Workability Ear incidence rate (%) Crack Processing Precipitate size (um) Alloy ratio (area%) Corrosion Aging Characteristics Naesae geuseong High-temperature strength
Comparative material 1 81 X - Breaking 0.004 8.4 O X X X
Invention material 1 98 O 1.80 Good 0.034 10.4 O O O O
Invention material 2 96 O 1.86 Good 0.026 19.8 O O O O
Invention Reset 97 O 1.67 Good 0.045 14.2 O O O O
Invention re-4 96 O 1.98 Good 0.068 17.9 O O O O
Comparative Material 2 93 X 3.9 Good 0.006 10.2 O X O O
Invention material 5 97 O 2.13 Good 0.051 8.4 O O O O
Invention material 6 99 O 2.26 Good 0.054 14.6 O O O O
Compare Resume 92 X - Breaking 0.018 4.1 X X X X
Invention material 7 98 O 2.19 Good 0.071 15.7 O O O O
Compare Re 4 100 X 4.12 Good 0.008 2.8 X X X X
Compare Re 5 94 X 4.54 Good 0.026 32.4 O X X X
Compare Re 6 93 O 2.24 Good 0.009 4.3 X X X X
Compare Re 7 92 X - Breaking 0.003 11.4 O X O O
Compare reconfiguration 94 X - Breaking - 3.1 X X X X
Compare 9 Re 87 X 3.67 Good 0.126 6.4 O X X X
Compare Re 10 96 X - Breaking - 9.2 O X X X

[196]
(And in Table 3 PF it refers to polygonal ferrite, the microstructure other than the PF is acicular ferrite.)
[197]
As shown in Table 3, the invention material (1-4), which satisfies the range of the present invention (V, B) dynamic strain aging in the material at a high temperature rating or the like (C, N) based size optimization of the composite precipitate this phenomenon was not caused even high-temperature strength was able to get my sag Saints favorable results than 110MPa.
[198]
In addition, cold work ear test generation rate by drawing in the case of the machining steps is not generated at the same time, less than 3% even machining deteriorated can be seen that even at room temperature excellent workability.
[199]
Further, in the salt spray test of the work piece material for these aspects of the present invention (1-4) alloy also 5-25% level for 12 hours of the salt spray test because the period has not elapsed rust FIG ever generated according to the obtained satisfies the corrosion resistance aiming Could.
[200]
On the other hand, but that the invention steel, such as steel ingredients of Table 1 satisfy the range of the present invention, a comparative material (1-5) outside the scope of some of the process conditions of Table 2, the present invention is most precipitate size difference or recrystallization were not have the excellent high-temperature properties according to not proceed, it can be seen that even if plenty workability and Nash Hyosung poor.
[201]
In addition, the process conditions of Table 2 is one satisfying the range of the present invention, the alloy of Table 1, the steel components of V, B, W, etc. The comparison material (6-10) outside the scope of the present invention the precipitate size, and the coating layer this was fraction were out of the scope of the present invention, it can be seen that a plenty when the room temperature and high temperature properties poor.
[202]
For the comparative material 6 of but Ear incidence of 2.24%, and the drawing does not occur processing breakage during processing workability was good, there was no possible to secure the corrosion resistance of this alloy ratio less defects in general the high-temperature characteristics at 600 ℃ were, since according to the invention is lower than the composition range of the addition amount of the components such as V, W this module (V, B) (C, N) had the effect of forming the composite precipitates reduction system. Then, the comparison material (7-10) were difficult to satisfy the room temperature formability and high-temperature properties at the same time according to the number N to not only the steel element amount employed is room temperature workability poor increased, ensuring that the bar is also the target high-temperature characteristics.
[203]
Consequently, by optimizing the conditions of the river component conditions as in the process an appropriate size (V, B) (C, N) system to form a composite precipitate, this high-temperature characteristics at a low cost by using, by securing alloy layer fraction of the alloying process of the and processing that meet the corrosion resistance and workability at the same time and can be produced a heat-resistant cold-rolled steel sheet
[204]
[205]
The embodiment but the present invention is used as one example of which is limited. It has substantially the same configuration as the technical concept described in claims of the present invention achieve the same operation and effect are also included in the technical scope of the present invention would no.

Claims
[Claim 1]
By weight%, C: 0.0005 ~ 0.003%, Mn: 0.30 ~ 0.70%, Al: 0.02 ~ 0.10%, P: 0.003 ~ 0.020%, N: 0.002 ~ 0.006%, S: less than 0.015% (including 0%), V: 0.01 ~ 0.05%, B: 0.0005 ~ 0.0035%, W: including 0.04 ~ 0.10%, the balance Fe and other inevitable impurities; The following relation (1), the V and C, and the effective atomic ratio of 0.00009 ~ 0.00069 N for B to be represented by a; [Expression 1] (V * 1.2B) / (C + N) + (atomic ratio = (V weight% / 51) * 1.2 (B wt% / 11) / {(C wt.% / 12 herein) (N wt% / 14)} to a wanted) microstructure is at least 95% poly area% polygonal ferrite, and 5% or less (0% is containing acicular ferrite not included); And 0.01 ~ 0.10㎛ size (V, B) are cold-rolled steel sheet excellent workability, including (C, N) precipitates.
[Claim 2]
The method of claim 1, wherein the cold-rolled steel sheet is cold-rolled steel sheet with excellent workability comprising the alloy plating layer.
[Claim 3]
Claim 2 wherein said alloy plated layer is Ni-Fe cold-rolled steel sheet with excellent workability, it characterized in that the alloy plating layer.
[Claim 4]
According to claim 3, wherein said alloy plated layer is in area percent, 5-25% of the Fe-Ni having excellent workability, characterized in that the cold-rolled steel sheet to alloy the coating layer.
[Claim 5]
The method of claim 4, wherein the Fe-Ni alloy plate layer is obtained by alloying the Ni plating layer, the cold-rolled steel sheet having excellent workability is the thickness of the Ni plating layer, characterized in that 1 ~ 5㎛.
[Claim 6]
Any one of claims 1 to 5 according to any one of claims, wherein the thickness of the cold-rolled steel sheet excellent in cold-rolled steel sheet 0.1 ~ workability, characterized in that 0.4mm.
[Claim 7]
In weight% C: 0.0005 ~ 0.003%, Mn: 0.30 ~ 0.70%, Al: 0.02 ~ 0.10%, P: 0.003 ~ 0.020%, N: 0.002 ~ 0.006%, S: less than 0.015% (including 0%), V : 0.01 ~ 0.05%, B: 0.0005 ~ 0.0035%, W: 0.04 ~ 0.10%, the balance Fe and other inevitable C and N of the active atom relative to the V and B represented by the following, and including impurities relational expression (1) slab heating step of heating the ratio of the steel slab 0.00009 ~ 0.00069; [Expression 1] (V * 1.2B) / (C + N) + (atomic ratio = (V weight% / 51) * 1.2 (B wt% / 11) / {(C wt.% / 12 herein) (N wt% / 14)} to a wanted) by hot-rolling the heated slab to finish rolling temperature of 900 ~ 950 ℃ hot rolling step to obtain a hot-rolled steel sheet; Winding step for winding the hot-rolled steel sheet from 560 ~ 680 ℃; Cold rolling to obtain a cold-rolled steel sheet and cold rolling the hot-rolled steel sheet; And a method for producing the cold-rolled steel sheet to 680 ~ 780 ℃ After heating to temperature, good processability, including a heat treatment step of cooling at a cooling rate of 40 ~ 70 ℃ / sec of the cold-rolled steel sheet.
[Claim 8]
The method of claim 7, wherein in the heat treatment step the cooling end temperature is 450 to process for producing a cold-rolled steel sheet with excellent workability, characterized in that 350 ℃.
[Claim 9]
The method of claim 7, wherein the method of producing a cold-rolled steel sheet having excellent workability, further comprising a plating step of forming a plating layer on a cold-rolled steel sheet cooled in the cooling step.
[Claim 10]
The method of claim 7, wherein the method of producing a cold-rolled steel sheet having excellent workability, further comprising a heat treatment step of obtaining the alloy plating layer alloyed by the alloying treatment of the plating step and the plating layer for forming a plating layer on a cold-rolled steel sheet cooled in the cooling step.
[Claim 11]
The method of claim 7, Ni plating step and is excellent in workability that by alloying the Ni plate layer further comprises the alloying heat treatment step of obtaining the Fe-Ni alloy plating the cold-rolled steel sheet to form a Ni plating layer on the cold rolled steel cooled in the cooling step the method of manufacture.
[Claim 12]
In the alloying treatment step is in% by area. The method of 5 to 25% of the Fe-Ni having excellent workability, characterized in that to perform so as to form a plating layer alloyed cold-rolled steel sheet according to claim 11.
[Claim 13]
12. The method of claim 11, wherein the thickness of the Ni plate layer to be formed in the Ni plating steps 1 ~ 5㎛ method of producing a cold-rolled steel sheet with excellent workability, characterized in that.
[Claim 14]
12. The method of claim 11, wherein the alloying step is the manufacture of cold-rolled steel sheet having excellent formability, comprising a step carried out at 650 ~ 750 ℃.