JP2908641B2 - Manufacturing method of thin steel sheet with excellent deep drawability - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention proposes a method for producing a hot-rolled thin steel sheet having excellent deep drawability which is useful for a steel sheet for automobiles and the like.

[0002] Thin steel sheets for deep drawing used for automobile panels and the like are required to have excellent deep drawability as characteristics. In order to improve the deep drawability, it is important to give a steel sheet a high Rankford value (average r value) and a high ductility (El) as mechanical properties. Cold rolled steel sheets manufactured by subjecting such deep-drawn thin steel sheets to hot rolling at an Ar ₃ transformation point or higher and then cold rolling to a thin sheet having the final thickness, and then performing recrystallization annealing are generally used. Is used regularly.
However, in recent years, for the purpose of cost reduction, there has been an increasing demand for replacing members that conventionally used cold-rolled steel sheets with hot-rolled steel sheets.

In recent years, the tensile strength has been increased to 35 to 60 for the purpose of reducing the weight of a vehicle body and improving safety.
Motivation to use high-strength steel sheets such as Kgf / mm ² has been rapidly increasing. It is needless to say that even such a high-strength steel sheet is required to exhibit excellent deep drawability during press forming. .

[0004]

2. Description of the Related Art However, in order to ensure workability, particularly ductility, conventional hot-rolled steel sheets for processing have been rolled at an Ar ₃ transformation point or higher to avoid the formation of an unrecrystallized ferrite structure. Therefore, in general, the texture is randomized during the γ → α transformation, so that the deep drawability of the hot-rolled steel sheet is significantly inferior to that of the cold-rolled steel sheet.

Heretofore, there are several disclosures of a hot-rolled steel sheet excellent in deep drawability and a manufacturing method. For example,
JP-A-59-226149 discloses a hot-rolled steel sheet having excellent formability and a method for producing the hot-rolled steel sheet: C: 0.002%, Si: 0.02%, Mn:
0.23%, P: 0.009%, S: 0.008%, Al: 0.025
%, N: 0.0021%, Ti: 0.10% low-carbon Al-killed steel, with a reduction rate of 76% or 93% while applying lubricating oil in the temperature range of 500 to 900 ° C from the beginning of finish rolling. A production example of a thin steel sheet having characteristics of an average r value of 1.21 or 1.48 by rolling into a steel strip having a thickness of 1.6 mm and performing recrystallization annealing is shown. Further, the method for producing a high r-value hot-rolled steel sheet disclosed in JP-A-62-192539 includes C: 0.008%, Si: 0.04%,
Mn: 1.53%, P: 0.015%, S: 0.004%, Ti: 0.068
%, Nb: 0.024% of low carbon Al killed steel, from Ar _{3 to} Ar ₃
A production example of a thin steel sheet having a characteristic of an average r value of about 1.41 by rolling in a temperature range of + 150 ° C. and performing recrystallization annealing is shown. However, the average r value obtained by these means is at most about 1.5, and it cannot be said that the deep drawability is sufficiently satisfied.

On the other hand, in order to cope with the lightening of the vehicle body and the improvement of safety as described above, research and development of a steel plate having higher strength and a deep drawability equal to or higher than that of conventional steel has been promoted. However, for research on hot-rolled steel sheets with higher strength and excellent deep drawability,
At present, little is done.

[0007]

SUMMARY OF THE INVENTION The present invention advantageously solves the above-mentioned problems, and has higher strength and is far superior to conventional steels by regulating the composition of the steel and the production conditions. An object of the present invention is to propose a method for producing a hot-rolled thin steel sheet having deep drawability.

[0008]

DISCLOSURE OF THE INVENTION The present invention has been intensively studied to improve the deep drawability, and as a result, it has been found that a thin steel sheet having excellent deep drawability can be manufactured without performing cold rolling. is there.

That is, the gist of the present invention is as follows: C: 0.01 wt% or less, Si: 2.0 wt% or less, Mn: 3.0 wt% or less, P: 0.20 wt% or less, S: 0.05 wt% or less, Al: 0.01 wt% % Or more, 0.20 wt% or less and N: 0.01 wt% or less, and one or two of Ti: 0.005 wt% or more and 0.2 wt% or less and Nb: 0.001 wt% or more and 0.2 wt% or less. , The balance being iron and a sheet bar having the composition of unavoidable impurities, and starting the finish hot rolling at a temperature equal to or higher than the Ar ₃ transformation point, and at 20 ° C. without rolling during the rolling. / S cooling rate
And 30 ° C. or more temperatures below Ar ₃ transformation point to cool, subsequently following Ar ₃ transformation point, 500 while applying a lubricant at ° C. or higher temperature region Ar ₃ transformation point of the total reduction of 50% or more, 95
% Is a method for producing a thin steel sheet having excellent deep drawability, characterized in that the steel sheet is subjected to a recrystallization treatment in a winding or annealing step after being rolled to a final thickness by rolling of not more than% (first invention),

A method for producing a thin steel sheet having excellent deep drawability, comprising: B: not less than 0.0001 wt% and not more than 0.0050 wt% by substituting a part of the iron of the first invention (second invention), Ni: 0.1 wt% or more, 1.5 wt% or less, Mo: 0.01 wt% or more, 1.5 wt% or less, and Cu: 0.1 wt% or more, 1.5 wt% by substituting a part of the iron of the first or second invention. A method for producing a thin steel sheet having excellent deep drawability comprising one or more of the following (third invention and fourth invention):

Further, the method for producing a thin steel sheet excellent in deep drawability, characterized in that the recrystallization treatment of the first, second, third or fourth invention is performed in a continuous hot-dip galvanizing step (fifth invention). It is.

[0012]

The present invention will be described below in more detail. First,
The experimental results on which the present invention is based will be described.

C: 0.002 wt%, Si: 0.01 wt%, Mn:
0.15wt%, P: 0.01wt%, S: 0.005wt%, Al: 0.05w
t%, N: 0.002 wt%, Ti: 0.045 wt%, and Nb: 0.015
A steel slab containing wt% is heated and soaked to a temperature of 1150 ° C and then coarsely rolled, and the finish rolling start temperature: 920 ° C, the rolling finish temperature: 700 ° C, and the rolling reduction below the Ar ₃ transformation point: 70% hot Rolling was performed to set the plate thickness to 1.6 mm.

At this time, the cooling in the temperature range sandwiching the Ar ₃ transformation point (870 ° C.) between the finish rolling passes is performed at a cooling rate of 50 ° C. /
s, and the temperature difference between the cooling start temperature and the cooling end temperature (hereinafter simply referred to as cooling temperature difference) was changed. Rolling in the temperature range below the Ar ₃ transformation point after cooling was lubricated rolling, and the lubricating rolling was adjusted so that the rolling finish temperature was 700 ° C. Following the above hot rolling, recrystallization annealing at 750 ° C. for 5 hours was performed, and the average r value of the obtained hot rolled steel sheet was examined.

FIG. 1 summarizes the results of these investigations.
FIG. 1 is a graph showing the relationship between the cooling temperature difference and the average r value. As is clear from this figure, the average r value strongly depends on the cooling temperature difference, and is higher when the cooling temperature difference is 30 ° C. or more. An average r value is obtained.

C: 0.002 wt%, Si: 0.01 wt%, Mn:
0.17wt%, P: 0.01wt%, S: 0.005wt%, Al: 0.05w
t%, N: 0.002 wt%, Ti: 0.048 wt% and Nb: 0.017
A steel slab containing wt% is heated and soaked to a temperature of 1150 ° C and then coarsely rolled, and the finish rolling start temperature: 920 ° C, the rolling finish temperature: 700 ° C, and the rolling reduction below the Ar ₃ transformation point: 70% hot Rolling was performed to set the plate thickness to 1.6 mm.

At this time, the cooling in the temperature range sandwiching the Ar ₃ transformation point (870 ° C.) between the finish rolling passes is performed by a cooling temperature difference of 50 ° C.
And the cooling rate was changed. Rolling in the temperature range below the Ar ₃ transformation point after cooling was lubricated rolling, and the lubricating rolling was adjusted so that the rolling finish temperature was 700 ° C. Following the hot rolling, recrystallization annealing at 750 ° C. for 5 hours was performed, and the average r value of the obtained hot rolled steel sheet was examined.

FIG. 2 summarizes the results of these investigations.
FIG. 2 is a graph showing the effect of the cooling rate on the average r value. As is clear from this figure, the average r value strongly depends on the cooling rate, and is higher when the cooling rate is set to 20 ° C./s or more. An average r value is obtained.

C: 0.002 wt%, Si: 0.01 wt%, Mn:
0.11wt%, P: 0.01wt%, S: 0.006wt%, Al: 0.05w
t%, N: 0.002 wt%, Ti: 0.052 wt% and Nb: 0.015
The steel slab containing wt% is heated and soaked to a temperature of 1150 ° C, then rough-rolled, and finish rolling is started at a temperature above the Ar ₃ transformation point, and the rolling finishing temperature is changed in a temperature range of 600 to 930 ° C. Hot rolling was performed to obtain a sheet thickness of 1.6 mm.

At this time, the cooling rate between the finish rolling passes was set at a cooling rate of 30 ° C./s, a cooling temperature difference was set at 50 ° C., and the sample after cooling was in a temperature range below the Ar ₃ transformation point (870 ° C.). About 70% reduction in the temperature range below the Ar ₃ transformation point,
The rolling was performed in two ways, lubricated rolling and non-lubricated rolling. Following the above hot rolling, recrystallization annealing at 750 ° C. for 5 hours was performed, and the average r value of the obtained hot rolled steel sheet was examined.

FIG. 3 summarizes the results of these investigations.
FIG. 3 is a graph showing the influence of the rolling finish temperature on the average r value and the presence or absence of lubrication in the rolling in a temperature range below the Ar ₃ transformation point. strongly depends on the presence or absence of lubrication time, a finish rolling temperature of less Ar ₃ transformation point, and a high average r value is obtained by a lubricating rolling rolling below Ar ₃ transformation point.

As a result of further studies based on the above experimental results, the scope of the present invention was limited as follows.

(1) Composition of Steel In the present invention, the composition of steel is important.
01 wt% or less, Si: 2.0 wt% or less, Mn: 3.0 wt% or less,
P: 0.20 wt% or less, S: 0.05 wt% or less, Al: 0.01-0.
20 wt% and N: 0.01 wt% or less, and Ti: 0.005 to
It is necessary to contain one or two of 0.2 wt% and Nb: 0.001 to 0.2 wt%. If necessary,
B: 0.0001 to 0.0050 wt% and / or Ni: 0.1 to 1.5 wt%
%, Mo: 0.01 to 1.5 wt%, and Cu: 0.1 to 1.5 wt%. One or more of these may be contained. If the steel composition does not satisfy these conditions, excellent deep drawability is obtained. Cannot be obtained.

The reasons for limiting each component are described below. C: 0.01 wt% or less C is preferred as the smaller the content, the better the deep drawability is improved. However, since the content is not so bad up to 0.01 wt%, the upper limit of the content is 0.01 wt%. I do.

Si: 2.0 wt% or less Si has the effect of strengthening steel and is contained in a necessary amount depending on the desired strength. However, if the content exceeds 2.0 wt%, deep drawability and surface properties Adversely affect Therefore, its content is limited to 2.0 wt%.

Mn: 3.0 wt% or less Mn has an effect of strengthening steel, and is contained in a necessary amount according to a desired strength. However, if the content exceeds 3.0% by weight, the deep drawability is adversely affected, so the content is limited to 3.0% by weight.

P: 0.2 wt% or less P has the effect of strengthening steel, and is contained in a necessary amount depending on the desired strength. However, if the content exceeds 0.20 wt%, deep drawability is adversely affected. Therefore, its content is 0.2
The upper limit is 0 wt%.

S: 0.05 wt% or less S is preferably as small as possible because the deep drawability is improved. However, since the content of S does not significantly affect up to 0.05 wt%, the upper limit of the content is set to 0.05%. wt%.

Al: 0.01 to 0.20 wt% Al is deoxidized and added as needed to improve the yield of carbonitride-forming components, but the content is 0.01 wt%.
If the amount is less than 0.2 wt%, no further effect is obtained, and conversely, the ductility is deteriorated. Therefore, if the content is 0.01 wt% or more, 0.2 wt%
wt% or less.

N: 0.01 wt% or less N is preferably as small as possible because the deep drawability is improved. However, since the content of N does not significantly affect up to 0.01 wt%, its content is 0.01 wt%. Is the upper limit.

Ti: 0.005 to 0.2 wt% Ti has the effect of precipitating and forming {111} orientation, which is advantageous for deep drawability, by fixing solid solution C and solid solution N in steel as carbonitride. is there. If the content is less than 0.005% by weight, the effect is not obtained. On the other hand, if the content exceeds 0.2% by weight, no further effect is obtained, and conversely, the ductility is deteriorated.
Therefore, its content should be 0.005 wt% or more and 0.2 wt% or less. In addition, it is preferable in terms of material to satisfy the relational expression of Ti / 48 ≧ (C / 12 + N / 14).

Nb: 0.001 to 0.2 wt% Nb precipitates and fixes solid solution C in steel as carbide.
The effect of preferentially forming the {111} orientation, which is advantageous for deep drawability, by miniaturizing the structure before finish rolling or the like. If the content is less than 0.001 wt%, there is no effect.
Even if the content exceeds wt%, no further effect can be obtained, and on the contrary, the ductility is deteriorated. Therefore, its content is
0.001 wt% or more and 0.2 wt% or less. In addition, Nb / 93 ≧
It is preferable from the viewpoint of the material to satisfy the relational expression of C / 12.

B: 0.0001 to 0.005 wt% B is contained for improving secondary work brittleness resistance. If the content is less than 0.0001 wt%, the effect is not obtained.
If the content exceeds 5 wt%, the deep drawability deteriorates. Therefore, its content should be 0.0001 wt% or more and 0.005 wt% or less.

Ni: 0.1-1.5 wt% Ni has the effect of strengthening the steel and is effective in improving the surface properties of the steel sheet when Cu is added. The effect is the content
It is expressed at 0.1 wt% or more, but if it exceeds 1.5 wt%, deep drawability is adversely affected. Therefore, its content should be 0.1 wt% or more and 1.5 wt% or less.

Mo: 0.01 to 1.5 wt% Mo has an effect of strengthening steel, and is contained in a necessary amount according to a desired strength. The effect is exhibited when the content is 0.01 wt% or more, but when the content exceeds 1.5 wt%, the deep drawability is adversely affected. Therefore, its content is more than 0.01wt%,
1.5 wt% or less.

Cu: 0.1 to 1.5 wt% Cu has an effect of strengthening steel, and is contained in a necessary amount according to a desired strength. The effect is exhibited when the content is 0.1 wt% or more. However, when the content exceeds 1.5 wt%, deep drawability and surface properties are adversely affected. Therefore, its content is
0.1 wt% or more and 1.5 wt% or less.

(2) Hot Rolling The hot rolling step is the most important in the present invention. In performing the finish hot rolling to the final predetermined thickness, the finish rolling should be started at a temperature not lower than the Ar ₃ transformation point. , And without cooling during the rolling, cooling rate: 20 ° C /
Cooling temperature difference across the Ar ₃ transformation point: s or more: After cooling at 30 ° C. or more, the total pressure drop below the Ar ₃ transformation point while lubricating in the temperature range of the Ar ₃ transformation point or less and 500 ° C. or more Rate 50
It is necessary to perform rolling processing of not less than 95% and not more than 95%.

The finish rolling start temperature is set to the Ar ₃ transformation point or higher. If the temperature is lower than this temperature, the refinement of γ grains cannot be performed by finish rolling. As a result, the {111} texture Are not formed, so that only low average r values are obtained. Further, after the finish rolling is started at the Ar ₃ transformation point or higher, the cooling rate is determined without rolling during the rolling.
20 ° C. / s or higher, the cooling temperature difference: although at 30 ° C. or higher and requires cooling to temperatures below Ar ₃ transformation point, fine rolling of such cooling is not performed when the Ar ₃ transformation point or more of the temperature Since the transformed γ grains are again coarsened, no {111} texture is formed in the hot-rolled sheet, and only a low average r value can be obtained as is clear from the above-described experimental results. The cooling with the Ar ₃ transformation point in between can be performed between intermediate stands or between one and three stands in the finishing mill group.

The rolling temperature after cooling across the Ar ₃ transformation point is A
The r ₃ transformation point or more temperature range, texture by much rolling also gamma → alpha transformation and is to randomize, result in poor average r value not {111} texture in the hot-rolled steel sheet is formed. On the other hand, even if the rolling temperature is lowered to less than 500 ° C,
Further improvement in the average r value cannot be expected, but only increases the rolling load. Therefore, the rolling temperature after cooling should be lower than the Ar ₃ transformation point and higher than 500 ° C.

When the total rolling reduction below the Ar ₃ transformation point in the finish rolling is less than 50%, no {111} texture is formed in the hot-rolled steel sheet. r
As a result, an undesirable texture may be formed, and the total rolling reduction below the Ar ₃ transformation point is 50% or more and 95% or less.
% Or less.

If rolling below the Ar ₃ transformation point is performed without lubrication, the {110} orientation, which is not preferred for deep drawing, is changed to the surface layer of the steel sheet due to shear deformation caused by the frictional force between the roll and the steel sheet. As is clear from the above experimental results, it is not possible to expect an increase in the average r value, so it is necessary to perform lubrication rolling in order to ensure deep drawability.

As for the rolled material, a steel bar which is made by reheating a steelmaking and continuously cast slab according to a conventional method, or immediately after the continuous casting or by performing a heat retaining treatment and rough rolling to form a sheet bar is used. The roll diameter, the structure of the roll and the rolling mill, the type of lubricating oil, and the like may be arbitrary.

(3) Recrystallization Treatment In the present invention, since the rolling temperature after cooling during finish rolling is equal to or lower than the Ar ₃ transformation point, the as-rolled hot-rolled steel sheet has a processed structure. Therefore, it is necessary to subject the as-rolled hot-rolled steel sheet to a recrystallization treatment to form a {111} texture. Unless this recrystallization treatment is performed, a {111} texture is not formed, so that a high average r value cannot be obtained.

The recrystallization treatment can be performed in a winding step after hot rolling or a recrystallization annealing step. When performing recrystallization treatment in the winding process, it is important that the winding temperature be 650 ° C or higher. This is because if the winding temperature is lower than 650 ° C., recrystallization does not occur, so that the {111} orientation is not formed and improvement in the average r value cannot be expected. On the other hand, in the case of performing the recrystallization annealing step, both the batch annealing method and the continuous annealing method are suitable, and the annealing temperature is preferably 650 to 950 ° C. It is also good to anneal in the continuous hot-dip galvanizing process,
Subsequent to this annealing, zinc plating can be applied.

The steel sheet after the hot rolling and the recrystallization treatment is subjected to a rolling reduction in order to correct the shape and adjust the surface roughness.
Temper rolling of 10% or less may be added, and the hot-rolled thin steel sheet obtained according to the present invention can be applied as a raw material of a surface-treated steel sheet for processing and a raw material of a cold-rolled steel sheet. Examples of the surface treatment include zinc plating (including alloys), tin plating, and enamel.

[0046]

EXAMPLE After roughly rolling a steel slab adjusted to the composition shown in Table 1, the steel slab was subjected to finish rolling under the conditions shown in Table 2 using a 7-stand hot rolling mill, followed by recrystallization treatment also shown in Table 2. Was done.

[0047]

[Table 1]

[0048]

[Table 2]

[0049] Incidentally, the sample No.1~3,9 and 11 F3 stand in Table 2, No. 7 is not performed each rolling in the F3 and F4 stands, the cooling sandwiching the Ar ₃ transformation point in this section went. Sample Nos. 5 and 6 were subjected to recrystallization annealing and plating in a continuous galvanizing facility.
The tensile properties of the steel sheet thus obtained were investigated. The results of this survey are shown in Table 2 above.

Here, the tensile properties were measured using a JIS No. 5 tensile test piece, the average r value was measured by a three-point method after giving a 15% tensile prestrain, and the L direction (rolling direction) As the average value of D direction (45 ° direction to rolling direction) and C direction (90 ° direction to rolling direction)

[Number 1] average r value = determined from _{(r L + 2r D + r} c) / 4.

As is evident from Table 2, the hot-rolled steel sheet conforming to the present invention and the galvanized steel sheet have excellent deep drawability as compared with the comparative example.

[0052]

According to the present invention, the composition of the ultra-low carbon steel is limited, and when the finish hot rolling is performed to the final thickness, Ar ₃
After start the finish rolling at a point above and cooled below the Ar ₃ point by performing the middle cooling 30 ° C. or higher at 20 ° C. / s or more cooling rate, lubrication rolling at a temperature range of Ar ₃ point to 500 ° C. By performing a recrystallization treatment after that, a hot-rolled thin steel sheet having excellent deep drawability is obtained, which can greatly contribute to the expansion of applications of a hot-rolled steel sheet having excellent economic efficiency.

[Brief description of the drawings]

FIG. 1 is a graph showing an influence of a cooling temperature difference on an average r value.

FIG. 2 is a graph showing the effect of the cooling rate on the average r value.

FIG. 3 is a graph showing the effect of the rolling finish temperature on the average r value and the presence or absence of lubrication in rolling in a temperature range below the Ar ₃ transformation point.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-253733 (JP, A) JP-A-3-100125 (JP, A) JP-A-61-159528 (JP, A) (58) Investigation Field (Int.Cl. ⁶ , DB name) C21D 8/02-8/04 C21D 9/46-9/48

Claims (5)

(57) [Claims] C: 0.01 wt% or less, Si: 2.0 wt% or less, Mn: 3.0 wt% or less, P: 0.20 wt% or less, S: 0.05 wt% or less, Al: 0.01 wt% or more, 0.20 wt% And N: 0.01 wt% or less, and one or two of Ti: 0.005 wt% or more and 0.2 wt% or less and Nb: 0.001 wt% or more and 0.2 wt% or less, with the balance being Using a sheet bar having the composition of iron and unavoidable impurities, finish hot rolling is started at a temperature of the Ar ₃ transformation point or higher, and a cooling rate of 20 ° C./s or higher without rolling during the rolling. so
And 30 ° C. or more temperatures below Ar ₃ transformation point to cool, subsequently following Ar ₃ transformation point, 500 while applying a lubricant at ° C. or higher temperature region Ar ₃ transformation point of the total reduction of 50% or more, 95
%. A method for producing a thin steel sheet having excellent deep drawability, wherein a redrawing treatment is performed in a winding or annealing step after a final sheet thickness is obtained by rolling at not more than 10%. 2. C: 0.01 wt% or less, Si: 2.0 wt% or less, Mn: 3.0 wt% or less, B: 0.0001 wt% or more, 0.0050 wt% or less, P: 0.20 wt% or less, S: 0.05 wt% Below, Al: 0.01 wt% or more, 0.20 wt% or less and N: 0.01 wt% or less, and Ti: 0.005 wt% or more, 0.2 wt% or less, and Nb: 0.001 wt% or more, 0.2 wt% or less The final hot rolling is started at a temperature of the Ar ₃ transformation point or higher using a sheet bar containing iron and unavoidable impurities as the raw material, and the remainder is rolled. At a cooling rate of 20 ° C / s or more without applying
And 30 ° C. or more temperatures below Ar ₃ transformation point to cool, subsequently following Ar ₃ transformation point, 500 while applying a lubricant at ° C. or higher temperature region Ar ₃ transformation point of the total reduction of 50% or more, 95
%. A method for producing a thin steel sheet having excellent deep drawability, wherein a redrawing treatment is performed in a winding or annealing step after a final sheet thickness is obtained by rolling at not more than 10%. 3. C: 0.01 wt% or less, Si: 2.0 wt% or less, Mn: 3.0 wt% or less, P: 0.20 wt% or less, S: 0.05 wt% or less, Al: 0.01 wt% or more, 0.20 wt% And N: 0.01 wt% or less, and one or two of Ti: 0.005 wt% or more, 0.2 wt% or less, and Nb: 0.001 wt% or more, 0.2 wt% or less, and Ni: 0.1 wt% or less. wt% or more, 1.5 wt% or less, Mo: 0.01 wt% or more, 1.5 wt% or less Cu: One or more of 0.1 wt% or more and 1.5 wt% or less, with the balance being iron and inevitable Using a sheet bar with the composition of impurities as a raw material, finish hot rolling is started at a temperature of the Ar ₃ transformation point or higher, and at a cooling rate of 20 ° C./s or higher without rolling during the rolling, 30 ° C. or higher. a temperature below Ar ₃ transformation point performs cooling, subsequently Ar ₃ or less transformation point, the total reduction of less than Ar ₃ transformation point while performing lubrication in a temperature range of not lower than 500 ° C. There more than 50%, after a final thickness by rolling of 95% or less, thin steel sheet manufacturing method which is excellent in deep drawability, characterized in that performing recrystallization by coiling or annealing process. 4. C: 0.01 wt% or less, Si: 2.0 wt% or less, Mn: 3.0 wt% or less, B: 0.0001 wt% or more, 0.0050 wt% or less, P: 0.20 wt% or less, S: 0.05 wt% Below, Al: 0.01 wt% or more, 0.20 wt% or less and N: 0.01 wt% or less, and Ti: 0.005 wt% or more, 0.2 wt% or less, and Nb: 0.001 wt% or more, 0.2 wt% or less One or two of the following, and one of Ni: 0.1 wt% or more and 1.5 wt% or less, Mo: 0.01 wt% or more and 1.5 wt% or less, Cu: 0.1 wt% or more and 1.5 wt% or less Or, two or more kinds are contained, and the rest is made of a sheet bar having a composition of iron and unavoidable impurities, and finish hot rolling is started at a temperature of the Ar ₃ transformation point or higher, and rolling is performed during the rolling. and 20 ° C. / s or more cooling rate at 30 ° C. or more temperatures below Ar ₃ transformation point to cool without subsequently Ar ₃ or less transformation point, lubrication at 500 ° C. or higher temperature range Deep drawing characterized by subjecting to a final sheet thickness by rolling at a total draft of 50% or more and 95% or less while transforming the Ar ₃ transformation point or less, and then performing a recrystallization treatment in a winding or annealing step. Method for manufacturing thin steel sheet with excellent heat resistance. 5. A method for producing a thin steel sheet excellent in deep drawability, wherein the recrystallization treatment according to claim 1, 2, 3, or 4 is performed in a continuous galvanizing step.