JPH055156A - High strength steel sheet for forming and its production - Google Patents

Abstract

(57) [Summary] [Structure] The weight ratio is C: 0.01 to 0.1%, Si: 0.1
~ 1.2%, Mn: 3.0% or less, Ti: (Ti% -1.5 S% -3.
43N%) / C% value is 4 to 12, B: 0.0005 to 0.005%,
Al: 0.1% or less, P: 0.1% or less, S: 0.02% or less,
N: A high-strength steel sheet for forming and processing containing 0.05% or less, and a steel slab containing the above component composition at 1100 to 1280 ° C.
A method for producing a steel sheet that is heated and hot-rolled in the temperature range described above, a method for producing a steel sheet that is cold-annealed from the hot-rolled sheet, and a method for producing a steel sheet that performs a plating treatment on these steel sheets. [Effect] It is possible to obtain a high-strength steel sheet having a small in-plane anisotropy, a low yield ratio, complete non-aging, and a high r-value that is unlikely to be softened by high temperature heating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention proposes a high-strength steel sheet having a tensile strength of 40 kgf / mm ² or more and a method for producing the same, which is suitable mainly for inner and outer plates for automobiles.

As a steel plate used for a vehicle body constituting member, an exterior plate, etc., a high strength steel plate has been widely adopted so far in order to reduce the weight of the vehicle body. Such high-strength steel sheets for automobiles need to have good formability represented by press work, and at the same time have sufficient strength required for ensuring vehicle safety. Is. in addition,
In recent years, under the situation where the regulations on the total amount of automobile exhaust gas have been remarkably strengthened, there is an urgent need to further increase the strength in the future. In addition, these steel sheets may be subjected to heat treatment at 900 ° C or higher to remove work strain after forming, or to improve resistance to secondary work brittleness, or may be heated to high temperatures by welding or brazing. However, it is also desired to have the property that softening does not easily occur when heated at high temperatures. Furthermore, from the viewpoint of rust prevention, which has been particularly emphasized in recent years, it is desired that the steel sheet be capable of various plating easily.

[0003]

2. Description of the Related Art High ductility is required for high strength steel sheets suitable for automobiles and having excellent workability.
It has a high r value, a low yield ratio, a small in-plane anisotropy of the material, and the like.

Regarding these, for example, JP-A-57-
No. 181361 discloses a cold rolled steel sheet for large-size forming which has excellent rigidity (high Young's modulus) and a method for producing the same, and Japanese Patent Laid-Open No. 58-58-
Japanese Patent No. 25436 discloses a method for producing a cold-rolled steel sheet for deep drawing with slow aging and small anisotropy. Both of these are based on ultra-low C steel, with a small amount of Nb, Ti, etc. added and controlling the continuous annealing conditions. Used as an ingredient. However, the tensile strength of this P-added ultra-low C steel is limited to at most about 40 kgf / mm ² class, and the composition system of solid-solution strengthening component based on the ultra-low C steel will advance rapidly in the future. It is clear that it will be difficult to meet the demand for higher strength of steel plates due to the weight reduction of automobile bodies, which is considered to be. Further, regarding the in-plane anisotropy which is expected to be required in the future, the above-mentioned JP-A-58-
As described in Japanese Patent No. 25436, these have a low tensile strength of 30 kgf / mm ² .

In addition to the P-containing solid solution strengthening steel sheet based on the ultra-low C steel as described above, there are transformation-strengthened steel sheet (composite steel sheet) and precipitation-strengthened steel sheet as high-strength steel sheets having different strengthening mechanisms. Among them, the transformed structure steel sheet is easy to obtain a low yield ratio and excellent elongation, but is not suitable for deep drawing because of its low r value.

On the other hand, precipitation strengthened steel sheets, so-called HSLA
(High Strength Low Alloy) Steel sheet is a steel containing Si, Mn, Nb, etc., and utilizes solid solution strengthening of Si and Mn, strengthening of Nb by carbonitride precipitation, and grain refinement strengthening by these. Although it is used not only for automobiles but also for home appliances, the drawback of this steel sheet is that the yield ratio is high, and therefore the conditions of use are limited. This precipitation-strengthened steel sheet will be described below by citing the literatures so far. JP-B-54-27822 discloses a method for producing a precipitation-strengthened high-strength cold-rolled steel sheet, and JP-B-55-16214 discloses a method for producing a high-strength cold-rolled steel sheet for deep drawing. In all cases, the yield ratio exceeds 70%, and most of them show high values of 80% or more. Further, Japanese Patent Application Laid-Open No. 55-152128 discloses a method for producing a precipitation-strengthened steel sheet by continuous annealing of a low yield ratio high strength cold-rolled steel sheet having excellent workability.
No deep drawability is mentioned.

Next, low C level Ti-IF (Interstitial)
As a Free steel, a cold-rolled steel sheet for ultra-deep drawing, which is excellent in secondary workability, is disclosed in JP-A-57-35662, and JP-A-6-63.
Japanese Unexamined Patent Publication No. 0-92453 discloses a cold-rolled steel sheet for brazing with excellent deep drawability. However, in contrast to the target tensile strength of the present invention of 40 kgf / mm ² or more, the Japanese Patent Laid-Open No.
According to the Japanese Patent Application Laid-Open No. 35662/1992, the tensile strength is 40
It is less than kgf / mm ² , and does not reach the target strength level of the present invention. Further, in the present invention, Si is an essential component, and its limiting range is 0.1 to 1.2 wt%, while
There is no description of Si in the claims of JP-A-60-92453, and the Si content is 0.09 wt% or less even in the examples, and the present invention that effectively utilizes the effect of Si is essentially different.

[0008]

DISCLOSURE OF THE INVENTION The present invention is based on a low C steel having a C content higher than that of a conventional ultra low C steel, is converted to IF by Ti, and the addition components are examined to determine the tensile strength. Of 40 kgf / mm ² or more, which has a lower yield ratio (less than 70%) and less in-plane anisotropy than conventional precipitation strengthened steels, and the softening caused by abnormal grain growth due to reheating treatment. The purpose is to propose a high-strength steel sheet that is unlikely to occur and a manufacturing method thereof.

[0009]

As a result of repeated experiments and examinations, the present invention adopts a low C-high Ti component system containing Si and complete IF conversion to achieve a low yield ratio. This is due to the finding that a high-strength steel sheet with small in-plane anisotropy can be obtained.

That is, the gist of the present invention is expressed by the following formula: C: 0.01 wt% to less than 0.1 wt%, Si: 0.1 wt% to 1.2 wt%, Mn: 3.0 wt%, Ti: Effective * Ti (wt%) and above C (wt%)
Ratio, that is, effective * Ti (wt%) / C (wt%) is 4 to 12
Until effective * Ti (wt%) = Ti (wt%)-1.5 S (wt%)-3.43N (wt
%) B: 0.0005 wt% to 0.005 wt%, Al: 0.1 wt%, P: 0.1 wt%, S: 0.02 wt%, and N: 0.005 wt%, with the balance being iron and A high-strength steel sheet for forming (invention 1) composed of unavoidable impurities. Substituting the balance of iron of the invention 1 for iron, V: 0.02 wt% to 0.2 wt%, Nb: 0.02 wt % To 0.2 wt% and Zr: 0.02 wt% to 0.2 wt% selected from the group consisting of one or more selected high-strength steel sheets for forming (second invention). Substituting the balance iron of the invention or the second invention,
Furthermore, Cr: 0.05 wt% to 1.5 wt%, Ni: 0.05 wt% to 2.0 wt%, Mo: 0.05 wt% to 1.0 wt%, and Cu: 0.05 wt% to 1.5 wt%. It is a high-strength steel sheet for forming process (third and fourth inventions) containing one or more selected from the above, and further substituting the remaining component iron of the first, second, third or fourth invention, , Ca: 0.0005 wt% to 0.005 wt% is a high-strength steel sheet for forming (5th, 6th, 7th, 8th inventions),

C: 0.01 wt% to less than 0.1 wt%, Si: 0.1 wt% to 1.2 wt%, Mn: 3.0 wt%, Ti: Effective * Ti (wt%) expressed by the following equation: Above C (wt%)
Ratio, that is, effective * Ti (wt%) / C (wt%) is 4 to 12
Until effective * Ti (wt%) = Ti (wt%)-1.5 S (wt%)-3.43N (wt
%) B: 0.0005 wt% to 0.005 wt%, Al: 0.1 wt%, P: 0.1 wt%, S: 0.02 wt%, and N: 0.005 wt% of steel slab, A method for producing a high-strength steel sheet for forming, characterized in that the steel slab is heated to 1100 ° C. or higher and 1280 ° C. or lower and then hot-rolled to form a hot-rolled sheet (No. 9)
Invention)), a method for producing a high-strength steel sheet for forming processing (10th invention), which is followed by hot rolling according to the 9th invention, and which is electroplated or hot-dipped. C: 0.01 wt% to 0.1 wt% %, Si: 0.1 wt% to 1.2 wt%, Mn: 3.0 wt%, Ti: Effective expressed by the following formula * Ti (wt%) and C (wt%) above
Ratio, that is, effective * Ti (wt%) / C (wt%) is 4 to 12
Until effective * Ti (wt%) = Ti (wt%)-1.5 S (wt%)-3.43N (wt
%) B: 0.0005 wt% to 0.005 wt%, Al: 0.1 wt%, P: 0.1 wt%, S: 0.02 wt%, and N: 0.005 wt% of steel slab, In the method for producing a high-strength steel sheet for forming (11th invention), which comprises heating the steel slab to 1100 ° C. or higher and 1280 ° C. or lower, followed by hot rolling, and then annealing at a recrystallization temperature or higher after cold rolling. There is a method for manufacturing a high-strength steel sheet for forming (12th invention), in which electroplating or hot dip plating is performed following the annealing described in the 11th invention.

[0012]

First, the experimental results which are the basis of the present invention will be described. Chemical composition is C: 0.05 wt%, Mn: 0.5 w
t%, Ti: 0.2 wt%, B: 0.0005 wt%, Al: 0.05 wt%,
P: 0.01 wt%, S: 0.001 wt%, N: 0.0015 wt%, and 12 kinds of cold-rolled sheets with 0.70 mm thickness, with Si content varied from 0 to 2.60 wt% The box was annealed at 700 ° C and the tensile properties were investigated.

From the results of this investigation, the relationship between the tensile property value and the Si content is shown in FIG. As is clear from FIG. 1, Si
Low YR-high El-high average r values are obtained in the content range of 0.1 to 1.2 wt%. This effect of Si is considered to be due to the ferrite purifying action of Si.

Next, the relationship between C and Ti was examined for the steel sheet which is not likely to be softened at high temperature at the same time as the formability. The chemical composition is Si: 0.5 wt%, Mn: 0.3 wt%,
B: 0.0012 wt%, Al: 0.04 wt%, P: 0.05 wt%, S:
32 kinds of steel materials containing 0.010 wt% and variously changed C and Ti contents were heated to 1200 ° C,
It was hot rolled at a finish rolling temperature of 900 ° C and wound at a temperature of 550 ° C to obtain a hot rolled sheet having a plate thickness of 3.00 mm. In addition, a part of the hot-rolled sheet was descaled, cold-rolled at a reduction rate of 75%, kept at 800 ° C for 40 seconds, and then continuously annealed under the conditions of cooling at 20 ° C / sec (without overaging), followed by elongation. The plate thickness is 0.
It was a 75 mm cold rolled sheet. The hot-rolled sheet and the cold-rolled sheet thus obtained were heated at 1000 ° C. for 1 hour and then cooled at 5 ° C./sec, and the crystal grain size was examined. The results of these surveys are summarized in Figures 2 (a) and (b).

FIGS. 2 (a) and 2 (b) show C w which affects the crystal grain size.
t% and effective * Ti wt% / C wt% (effective * Ti wt% = Ti wt% -1.5 S
wt%-3.43 N wt%), and as is clear from this figure, both hot and cold rolled sheets are effective * Ti wt
Since% / C wt% is 4 or more and the particle size number is large, if this value or more, it is effective for fixing C * Ti
It turns out that the amount is sufficient. Even if the heat treatment at 1000 ° C is performed, the C content is 0.01 wt% or more and the effective * Ti w
When t% / C wt% is 4 or more, coarsening of crystal grains is not observed, and the grain size number is 7 or more. The crystal grain size after heating does not soften if the grain size number is 7 or more.

From the above results, in order to prevent abnormal grain growth (softening prevention) during reheating, the C content should be 0.01 wt% or more,
The reason is to set the effective * Ti wt% / C wt% to 4 or more. The reason for this is that the Ti-based fine carbides that are formed are relatively stable even during reheating, so this is an abnormal grain. It is presumed that it is useful for restraining growth.

Further, as a result of detailed experiments, it was found that the Si content greatly affects the in-plane anisotropy and the r value. Figures 3 (a), (b), (c) and (d) show C: 0.05 wt% and Si: 0 w.
4 types of t%, 1.0 wt%, 1.5 wt% and 2.0 wt%, Mn: 0.0
1 wt%, Ti: 0.206 wt%, B: 0.0008 wt%, Al: 0.0
4 wt%, P: 0.01 wt%, S: 0.001 wt% and N: 0.00
Fig. 3 shows a pole figure of four types of cold-rolled steel sheets containing 14 wt% measured at box annealing at 720 ° C.
(a), (b), (c) and (d) each have a Si content of 0 w.
t%, 1.0 wt%, 1.5 wt% and 2.0 wt%. From these figures, (b) with Si content of 1.0 wt% has a strong {1
11} <112> shows the organization and <100> //
The development of the ND direction is weakening. This means that the in-plane anisotropy is small and the r value is increased, and the Si content is preferably around 1 wt%.

Next, the reasons for limiting the chemical composition range of the steel of the present invention will be described.

C: 0.01 to 0.1 wt% C has a target tensile strength of 40 at a content of less than 0.01 wt%.
Since kgf / mm ² or more cannot be obtained, it tends to soften at higher temperatures. On the other hand, if the content of 0.1 wt% or more is included, when manufactured by the continuous annealing method, the crystal grain growth property during annealing sharply decreases, and the desired ductility cannot be obtained. Therefore, its content should be from 0.01 wt% to less than 0.1 wt%.

Si: 0.1 to 1.2 wt% Si is an important component in the present invention, has the effect of discharging C from the ferrite, promoting precipitation of Ti carbide and coarsening of agglomerates, and its content is 0.1 wt. If it is less than%, the effect does not appear. On the other hand, if the content exceeds 1.2 wt%,
Due to the solid solution strengthening ability of Si itself, the ductility is rapidly deteriorated and the r value and various plating properties are deteriorated. Therefore, its content is from 0.1 wt% to 1.2 wt%,
From the viewpoint of improving in-plane anisotropy and r-value, from 0.4 wt% to 1.0
It is preferably up to wt%.

Mn: up to 3.0 wt% Mn is useful as a reinforcing component in steel. But 3.0 w
If it is contained in excess of t%, it will be excessively hardened and the ductility will be significantly deteriorated. Therefore, its content is limited to 3.0 wt%.

Ti: Effective * Ti (wt%) / C (wt%) 4 to 12 Ti is an important component in the present invention and is necessary for fixing C, S and N. If effective * Ti is less than 4C, C cannot be completely fixed, and as described above, reheating causes coarsening of crystal grains and softening. Also valid * Ti
If it contains more than 12 C, not only Ti will form an excessive solid solution to deteriorate the material, but also the surface quality of the steel sheet will be impaired. Therefore, its content is effective * Ti / C is 4 to 12
The range is satisfied. (Effective * Ti = Ti-1.5 S-3.43N)

B: 0.0005 to 0.005 wt% B is necessary for improving the secondary work embrittlement, and its content is
If less than 0.0005 wt%, the effect is insufficient, and 0.005 w
If it exceeds t%, the deep drawability deteriorates significantly. Therefore, its content should be from 0.0005 wt% to 0.005 wt%.

Al: up to 0.1 wt% Al is effective by fixing O in steel and combining with O * Ti
It is a component that is useful for avoiding a decrease in the amount, but 0.1 wt%
Even if the content exceeds 5, the effect will be saturated. Therefore, its content is limited to 0.1 wt%.

P: up to 0.1 wt% P is a very good solid solution strengthening component, but 0.1 wt%
If it is contained in excess of 1.0, the surface quality of the steel sheet is significantly deteriorated. Therefore, its content is limited to 0.1 wt%. It is preferable that P (wt%) / C (wt%) is less than 1.5 in relation to the C content.

S: up to 0.02 wt% S causes cracking during hot rolling, so
Its content is up to 0.02wt%.

N: up to 0.005 wt% N, if contained in a large amount, reduces the effective * Ti amount,
The r value and the ductility are deteriorated. Therefore, it is preferable that the content is small, but the upper limit is set to 0.005 wt%.

In the present invention, in addition to the above chemical composition, one or more kinds of V, Nb and Zr which are carbide forming components may be contained for the purpose of ensuring strength. The effect is exhibited when the content is 0.02 wt% or more, but if it exceeds 0.2 wt%, ductility is deteriorated. Therefore, the contents of V, Nb, and Zr are 0.02 each.
From wt% to 0.2 wt%. For the same purpose, one or more of the solid solution strengthening components Cr, Ni, Mo and Cu may be contained. The effect is exhibited when the content is 0.05 wt% or more, respectively, but if the content is excessive, the surface quality of the steel sheet deteriorates. Therefore, their contents range from 0.05 wt% for Cr to 1.5 wt% and 0.05 for Ni.
From wt% to 2.0 wt%, Mo from 0.05 wt% to 1.0 wt%
And Cu from 0.05 wt% to 1.5 wt%.

Further, for the purpose of controlling the shape of inclusions,
Ca can be added. The effect is that the content is 0.0005
It appears at wt% or more, but if it exceeds 0.005 wt%, the effect is not only saturated, but also the deterioration of the material becomes remarkable. Therefore, the content is set to 0.0005 wt% to 0.005 wt%.

Here, in the present invention, the reason why the low yield ratio can be obtained even though the strength is increased by using the low C steel having a larger C content than the ultra low C steel will be described below. That is, the reason is that by setting the effective * Ti / C to 4 or more, C, S and N are completely fixed and a complete IF conversion is achieved. Therefore, it is considered that a low yield ratio can be obtained by decreasing the effect of dislocation fixing action and increasing the number of mobile dislocations.

Next, the process conditions will be described. First,
The steel-making method may be carried out according to a conventional method, and the conditions are not particularly limited.

If the slab heating temperature is less than 1100 ° C., the workability deteriorates, and if it exceeds 1280 ° C., coarse grains appear and the material quality after that varies. Therefore, the slab heating temperature is 11
The temperature range is from 00 ℃ to 1280 ℃. In addition, from the viewpoint of energy saving, the continuous cast slab is reheated or continuously cast at 1100 ℃
Immediately or above 1100 ° C without lowering the temperature below 12
Rough rolling may be performed after heat retention at 80 ° C or lower. Regarding the hot rolling finishing temperature, if the temperature is too high, the final structure becomes coarse, which is disadvantageous to the ductility.
On the other hand, if it is too low, the elongation of the structure becomes remarkable and the rolling load also increases rapidly, which is not preferable in operation. Therefore, the hot rolling finishing temperature is Ar ₃ transformation point or more, Ar ₃ transformation point + 10
A temperature range of 0 ° C. or lower is preferable. The winding temperature after hot rolling may be in the temperature range of 400 ° C or higher and 700 ° C or lower in view of the pickling ability and the capacity of the winder.

In cold rolling, in order to obtain sufficient workability after annealing, the rolling reduction is preferably 55% or more. In annealing after cold rolling, the recrystallization temperature or higher is required for recrystallization. There is. However, the temperature is preferably lower than the Ac ₃ transformation point in order to avoid the formation of a composite structure after annealing. The annealing method is not particularly limited, and may be a continuous annealing method or a box annealing method.

With respect to the plating conditions, in the case of electroplating, the hot-rolled sheet and the cold-rolled sheet may be plated in a desired basis weight by a usual method. In the case of hot-dip galvanizing, in addition to the hot-dip alone line, It may be applied to a continuous hot dip coating line in the annealing step.

Further, these steel plates may be temper-rolled for the purpose of straightening the plate shape or the like by a rolling reduction (%) which is generally equal to the plate thickness (mm) in the common sense range. Further, the steel sheet according to the present invention may be subjected to special treatment after annealing or plating to improve chemical conversion treatment property, weldability, press formability, corrosion resistance and the like.

[0036]

EXAMPLE Continuous cast slabs of 26 compatible steel types of the present invention, 5 comparative steel types and a total of 31 steel types having the chemical composition shown in Table 1 and Table 2 melted in a converter were hot-rolled, respectively. The thickness was finished to 3.2 mm for steel symbols O, P, Q and R, and 2.8 mm for all other steel types. Further, hot-dip galvanizing was applied to some of them.

[0037]

[Table 1]

[0038]

[Table 2] The steel sheet thus obtained was examined for mechanical properties, aging index AI, and grain size number after heat treatment (reheating).
The hot rolling conditions and the survey results are shown in Tables 3 and 4.

[0039]

[Table 3]

[0040]

[Table 4]

Further, a part of the above hot-rolled sheet (having a slab heating temperature conforming to the present invention) is 75% after descaling.
Cold rolling at a reduction ratio of 0.80 mm or 0.70 mm and continuous annealing or box annealing, then a reduction ratio of 0.80% or
It was temper-rolled to 0.70%. Further, a part of them was electroplated or hot-dipped.

Mechanical properties of the thus obtained steel sheet including the average r value and Δr which is an index of in-plane anisotropy,
The aging index AI and the grain size number after heat treatment were investigated. The annealing conditions and the above-mentioned investigation results are shown in Tables 5 and 6.

[0043]

[Table 5]

[0044]

[Table 6] Here, each processing condition is as follows. The electroplating was Zn-Ni plating with a basis weight of 30 g / m ² . The hot dip is Zn plating or Al plating. The Zn plating is bath temperature: 475 ℃, penetration plate temperature: 475 ℃, dipping time: 3 seconds, alloying temperature: 485 ℃, basis weight 45 g / m ² The bath temperature: 650 ° C, penetration plate temperature: 650 ° C, immersion time: 3 seconds,
The unit weight was 30 g / m ³ . Heat treatment (reheat) condition is 9
After heating to 50 ° C. and holding for 30 minutes, slow cooling was performed at 5 ° C./sec.

As a test condition, the tensile test is JI
Using the S5 test piece, YS, TS, and El were investigated in the rolling direction. The r-value was obtained by measuring the width at the center of the test piece length direction at 15% strain and at three points 12.5 mm on both sides from the center, and the average r-value and Δr
Was calculated from the following formulas. Average r value = (r ₀ + r ₉₀ + 2r ₄₅ ) / 4 Δr = (r ₀ + r ₉₀ −2r ₄₅ ) / 4 Note that r ₀ , r ₄₅ , and r ₉₀ are in the rolling direction (r ₀ ) and the pressure direction, respectively. 45 ° direction (r ₄₅ ) and 90
Each r value in the ° direction (r ₉₀ ). The AI value was determined from the difference in deformation stress before and after aging after subjecting to 7.5% tensile prestrain, aging treatment at 100 ° C. for 30 minutes.

As is apparent from Tables 3, 4 and 5,6,
The conformity example of this invention has a tensile strength of 40 kgf / mm ² regardless of the presence or absence of plating and whether the annealing method is box annealing or continuous annealing.
The above is obtained, and the yield ratio is low (70% or less) and high El.
In addition, the grain size after the heat treatment is 7 or more, which shows the characteristic that softening due to reheating does not easily occur. Furthermore, the cold rolled sheet has a high average r value and Δr, which is an index of the in-plane anisotropy. Small, and the aging index AI is 1kgf /
Excellent properties such as complete non-aging secured at mm ² or less are shown.

[0047]

According to the present invention, even in the case of a low C steel level steel sheet having a C content higher than that of an ultra low C steel, solid solution C, S, N is obtained.
, Etc., the in-plane anisotropy is small, a high yield steel sheet with a low yield ratio, complete non-aging and hard to soften due to high temperature heating is obtained. High-strength precipitation strengthened steel can be obtained. Therefore, the present invention is useful for expanding the applications of precipitation-strengthened steel sheets due to its usefulness.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between tensile properties and Si content.

FIG. 2 (a) is a graph showing the relationship between C amount and ^* Ti / C (weight ratio) on the crystal grain size of a hot-rolled sheet after reheating at 1000 ° C., and (b) is a graph. It is a graph which shows the relationship of C amount and ^* Ti / C (weight ratio) which affect the crystal grain size after 1000 degreeC reheating treatment of a rolled sheet.

FIG. 3 (a) is a (200) pole figure of a steel sheet having a Si content of 0 wt%, and (b) is a (200) pole figure of a steel sheet having a Si content of 1 wt%. ) Is a (200) pole figure of a steel sheet having a Si content of 1.5 wt%, and (d) is a (200) pole figure of a steel sheet having a Si content of 2.0 wt%.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication C22C 38/00 W 7217-4K 38/14 (72) Inventor Fusao Togashi Kawasaki-cho, Chiba-shi, Chiba No. 1 Kawasaki Steel Co., Ltd. Technical Research Division (72) Inventor Masahiko Morita No. 1 Kawasaki-cho, Chiba City, Chiba Prefecture Kawasaki Steel Co., Ltd. Technical Research Division (72) Toshiyuki Kato No. 1 Kawasaki-cho, Chiba City Chiba Prefecture Kawasaki Steel Stock Technology Research Division

Claims (1)

Claims: C: 0.01 wt% to less than 0.1 wt%, Si: 0.1 wt% to 1.2 wt%, Mn: 3.0 wt%, Ti: Effective * Ti (wt%) and above C (wt%)
Ratio, that is, effective * Ti (wt%) / C (wt%) is 4 to 12
Until effective * Ti (wt%) = Ti (wt%)-1.5 S (wt%)-3.43N (wt
%) B: 0.0005 wt% to 0.005 wt%, Al: 0.1 wt%, P: 0.1 wt%, S: 0.02 wt%, and N: 0.005 wt%, with the balance being iron and A high-strength steel sheet for forming, which has a composition of inevitable impurities. 2. C: 0.01 wt% to less than 0.1 wt%, Si: 0.1 wt% to 1.2 wt%, Mn: 3.0 wt%, Ti: Effective * Ti (wt% ) And the above C (wt%)
Ratio, that is, effective * Ti (wt%) / C (wt%) is 4 to 12
Until effective * Ti (wt%) = Ti (wt%)-1.5 S (wt%)-3.43N (wt
%) B: 0.0005 wt% to 0.005 wt%, Al: 0.1 wt%, P: 0.1 wt%, S: 0.02 wt%, and N: 0.005 wt%, and V: 0.02 It contains one or more selected from wt% to 0.2 wt%, Nb: 0.02 wt% to 0.2 wt%, and Zr: 0.02 wt% to 0.2 wt%, and the balance is A high-strength steel sheet for forming and processing that is composed of iron and inevitable impurities. 3. C: 0.01 wt% to less than 0.1 wt%, Si: 0.1 wt% to 1.2 wt%, Mn: 3.0 wt%, Ti: Effective * Ti (wt% ) And the above C (wt%)
Ratio, that is, effective * Ti (wt%) / C (wt%) is 4 to 12
Until effective * Ti (wt%) = Ti (wt%)-1.5 S (wt%)-3.43N (wt
%) B: 0.0005 wt% to 0.005 wt%, Al: 0.1 wt%, P: 0.1 wt%, S: 0.02 wt%, and N: 0.005 wt%, and Cr: 0.05 wt% to 1.5 wt%, Ni: 0.05 wt% to 2.0 wt%, Mo: 0.05 wt% to 1.0 wt%, and Cu: 0.05 wt% to 1.5 wt% A high-strength steel sheet for forming, which contains one or more kinds and the balance is composed of iron and inevitable impurities. 4. C: 0.01 wt% to less than 0.1 wt%, Si: 0.1 wt% to 1.2 wt%, Mn: 3.0 wt%, Ti: Effective * Ti (wt% ) And the above C (wt%)
Ratio, that is, effective * Ti (wt%) / C (wt%) is 4 to 12
Until effective * Ti (wt%) = Ti (wt%)-1.5 S (wt%)-3.43N (wt
%) B: 0.0005 wt% to 0.005 wt%, Al: 0.1 wt%, P: 0.1 wt%, S: 0.02 wt%, and N: 0.005 wt%, and V: 0.02 Selected from wt% to 0.2 wt%, Nb: 0.02 wt% to 0.2 wt%, and Zr: 0.02 wt% to 0.2 wt% 1
One or more, Cr: 0.05 wt% to 1.5 wt%, Ni: 0.05 wt% to 2.0 wt%, Mo: 0.05 wt% to 1.0 wt%, and Cu: 0.05 wt% , A high-strength steel sheet for forming, which comprises one or more selected from the range of up to 1.5 wt% and the balance is composed of iron and inevitable impurities. 5. C: 0.01 wt% to less than 0.1 wt%, Si: 0.1 wt% to 1.2 wt%, Mn: 3.0 wt%, Ti: Effective * Ti (wt% ) And the above C (wt%)
Ratio, that is, effective * Ti (wt%) / C (wt%) is 4 to 12
Until effective * Ti (wt%) = Ti (wt%)-1.5 S (wt%)-3.43N (wt
%) B: 0.0005 wt% to 0.005 wt%, Ca: 0.0005 wt% to 0.005 wt%, Al: 0.1 wt%, P: 0.1 wt%, S: 0.02 wt%, and N: A high-strength steel sheet for forming that contains up to 0.005 wt% and the balance is iron and inevitable impurities. 6. C: 0.01 wt% to less than 0.1 wt%, Si: 0.1 wt% to 1.2 wt%, Mn: 3.0 wt%, Ti: Effective * Ti (wt% ) And the above C (wt%)
Ratio, that is, effective * Ti (wt%) / C (wt%) is 4 to 12
Until effective * Ti (wt%) = Ti (wt%)-1.5 S (wt%)-3.43N (wt
%) B: 0.0005 wt% to 0.005 wt%, Ca: 0.0005 wt% to 0.005 wt%, Al: 0.1 wt%, P: 0.1 wt%, S: 0.02 wt%, and N: Including up to 0.005 wt% and selected from V: 0.02 wt% to 0.2 wt%, Nb: 0.02 wt% to 0.2 wt%, and Zr: 0.02 wt% to 0.2 wt% A high-strength steel sheet for forming, which contains one or more kinds and the balance is composed of iron and inevitable impurities. 7. C: 0.01 wt% to less than 0.1 wt%, Si: 0.1 wt% to 1.2 wt%, Mn: 3.0 wt%, Ti: Effective * Ti (wt% ) And the above C (wt%)
Ratio, that is, effective * Ti (wt%) / C (wt%) is 4 to 12
Until effective * Ti (wt%) = Ti (wt%)-1.5 S (wt%)-3.43N (wt
%) B: 0.0005 wt% to 0.005 wt%, Ca: 0.0005 wt% to 0.005 wt%, Al: 0.1 wt%, P: 0.1 wt%, S: 0.02 wt%, and N: Including up to 0.005 wt%, Cr: 0.05 wt% to 1.5 wt%, Ni: 0.05 wt% to 2.0 wt%, Mo: 0.05 wt% to 1.0 wt%, and Cu: 0.05 wt% % To 1.5 wt% selected from the group consisting of 1 or 2 or more, with the balance being iron and inevitable impurities. 8. C: 0.01 wt% to less than 0.1 wt%, Si: 0.1 wt% to 1.2 wt%, Mn: 3.0 wt%, Ti: Effective * Ti (wt% ) And the above C (wt%)
Ratio, that is, effective * Ti (wt%) / C (wt%) is 4 to 12
Until effective * Ti (wt%) = Ti (wt%)-1.5 S (wt%)-3.43N (wt
%) B: 0.0005 wt% to 0.005 wt%, Ca: 0.0005 wt% to 0.005 wt%, Al: 0.1 wt%, P: 0.1 wt%, S: 0.02 wt%, and N: Included up to 0.005 wt% and selected from V: 0.02 wt% to 0.2 wt%, Nb: 0.02 wt% to 0.2 wt%, and Zr: 0.02 wt% to 0.2 wt% 1
One or more, Cr: 0.05 wt% to 1.5 wt%, Ni: 0.05 wt% to 2.0 wt%, Mo: 0.05 wt% to 1.0 wt%, and Cu: 0.05 wt% , A high-strength steel sheet for forming, which comprises one or more selected from the range of up to 1.5 wt% and the balance is composed of iron and inevitable impurities. 9. C: 0.01 wt% to less than 0.1 wt%, Si: 0.1 wt% to 1.2 wt%, Mn: 3.0 wt%, Ti: Effective * Ti (wt% ) And the above C (wt%)
Ratio, that is, effective * Ti (wt%) / C (wt%) is 4 to 12
Until effective * Ti (wt%) = Ti (wt%)-1.5 S (wt%)-3.43N (wt
%) B: 0.0005 wt% to 0.005 wt%, Al: 0.1 wt%, P: 0.1 wt%, S: 0.02 wt%, and N: 0.005 wt% of the steel slab as a material. A method for producing a high-strength steel sheet for forming, comprising heating the steel slab to 1100 ° C. or higher and 1280 ° C. or lower and then hot rolling to form a hot rolled sheet. 10. A method for producing a high-strength steel sheet for forming, which comprises performing electroplating or hot dip plating after the hot rolling according to claim 9. 11. C: 0.01 wt% to less than 0.1 wt%, Si: 0.1 wt% to 1.2 wt%, Mn: 3.0 wt%, Ti: Effective * Ti (wt% ) And the above C (wt%)
Ratio, that is, effective * Ti (wt%) / C (wt%) is 4 to 12
Until effective * Ti (wt%) = Ti (wt%)-1.5 S (wt%)-3.43N (wt
%) B: 0.0005 wt% to 0.005 wt%, Al: 0.1 wt%, P: 0.1 wt%, S: 0.02 wt%, and N: 0.005 wt% of steel slab as a material. A method for producing a high-strength steel sheet for forming, characterized in that the steel slab is heated to 1100 ° C. or higher and 1280 ° C. or lower, hot rolled, and then cold rolled and annealed at a recrystallization temperature or higher. 12. Following the annealing according to claim 11,
A method for producing a high-strength steel sheet for forming, which comprises performing electroplating or hot dip coating.