JPH03140416A - Production of cold rolled steel sheet for deep drawing by continuous annealing method - Google Patents

Abstract

PURPOSE:To obtain the steel sheet free from material deterioration in the top part and the bottom part of a coil by the use of a low-cost stock by limiting C content in an Al-killed steel to a specific value or below, inhibiting the abnormal growth of crystalline grains in a hot rolled plate, and specifying manufacturing conditions. CONSTITUTION:A molten steel having a composition consisting of, by weight, 0.008-0.035% C, 0.003-0.10% Si, 0.05-0.35% Mn, 0.001-0.10% P, 0.001-0.030% S, 0.020-0.10% SOlAl, 0.0005-0.0060% N, and the balance iron is formed into a slab by means of continuous casting, etc. This slab is heated up to 1000-1170 deg.C, finish rolling is completed at 890-960 deg.C, and channel cooling is applied to the part between the position of 18m from the head end of a steel strip and the position of 15m from the tail end of the steel strip. The upper limit of coiling temp. is specified so that it is 850 deg.C in the part of <18m from the head end, 760 deg.C at the position of 18m from the head end, 740 deg.C at the position of 50m from the head end, a temp. obtained by connecting 760 deg.C and 740 deg.C with a straight line in the part between the position of 18m from the head end and the position of <50 from the head end, 740 deg.C in the part between the position of 50m from the head end and the position of 30m from the tail end, 740 deg.C at the point of 30m from the tail end, 760 deg.C at the position of 15m from the tail end, a temp. obtained by connecting 740 deg.C and 760 deg.C with a straight line in the part between the position of <30m from the tail end and the position of 15m from the tail end, and 820 deg.C in the part of <15m from the tail end. The lower limits of coiling temp. in respective parts are specified in a similar manner.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for producing cold-rolled steel sheets for deep drawing at low cost by continuous annealing.

(Prior Art) Many inventions have been made in the past regarding the method for manufacturing cold rolled steel sheets by continuous annealing, and for example, the method for manufacturing cold rolled steel sheets for deep drawing by adding TI is disclosed in Japanese Patent Publication No. 44-18.
There is a publication No. 088. In addition, low carbon Ag without adding Ti
Many methods using killed steel have also been invented, for example:
There is Japanese Unexamined Patent Publication No. 51-66219.

In Japanese Patent Publication No. 18066/1986, which adds T1, an excellent material can be obtained, but it does not add expensive Ti or carbon in the steel.
Since the content must be extremely reduced, there is a problem that the manufacturing cost becomes too large, such as the cost of decarburization treatment in steel manufacturing becoming large.

On the other hand, in the method of using low carbon AN killed steel, there is a lot of material deterioration in the top part and bottom part of the coil manufactured by continuous annealing, and the material quality required for cold rolled steel sheets for deep drawing is not satisfied, resulting in a decrease in yield and production. There is a problem in that cost and productivity are significantly reduced.

The reason for this is that in the method using low-carbon Aj7 killed steel, high-temperature rolling must be performed during hot rolling in order to obtain good material quality, but in the commonly used high-temperature rolling method, after rolling The inner periphery of the coil contacts the reel of the winding machine and is rapidly cooled, and the outer periphery is rapidly cooled in the atmosphere.

Therefore, even if high-temperature winding is performed, the T and B portions are essentially equivalent to low-temperature winding, and the precipitation of AgN and coarsening of cementite agglomeration are insufficient on the inner and outer peripheries of the coil, resulting in deterioration of the material.

JP-A-51-68219 is a representative example of a conventional method for solving the problems of the T and B sections of Ag killed steel. However, as shown in Figure 3 of the same publication, when this method is applied to low carbon Ap killed, the F value is 1.
．． It is as low as 3 to 1.4, and the method of the present invention can only obtain a material that cannot be applied to cold-rolled steel sheets for deep drawing.

As described above, there is no method for producing cold-rolled steel sheets for deep drawing at low cost by continuous annealing.

(Problem to be solved by the invention) The problem to be solved by the present invention is to use low-carbon AI, which is a low-cost material. An object of the present invention is to provide a method for manufacturing a cold-rolled steel sheet for deep drawing by a continuous annealing method using guild steel and causing no material deterioration in the T and B parts of the coil.

(Means for solving the problem) The present inventors used low-cost low-carbon Al guild steel,
We conducted various studies on methods for producing cold-rolled steel sheets for deep drawing using continuous annealing methods that do not cause material deterioration in the T and B parts of the coil, and discovered for the first time a method for producing cold-rolled steel sheets for deep drawing using continuous annealing methods.

The gist of the present invention is C: 0.008-0.035%, S 0.003-0.10%, Mn: 0.05-0.35%.
, P: 0.001-0.10%, S: 0. OOl ~
o, oao%, sof, Ai) +0.020 to 0.1
0%, N: 0.0005-0.0060%, remaining unavoidable impurities and molten steel made of iron by continuous casting or ingot method, hot rolling, pickling, cold rolling,
In the manufacturing method of cold-rolled steel sheets for deep drawing which undergoes a continuous annealing process with over-aging treatment, the heating temperature of the slab (hereinafter referred to as SR) is
T) is 1000℃~1170℃, and 890~9
Finish rolling is completed at 60°C, and water is poured onto a run-out table (hereinafter referred to as ROT) for cooling over 18 m or more from the top of the hot-rolled steel strip in the longitudinal direction and 15 m or more from the bottom of the hot-rolled steel strip. 85 less than 18m from
0℃, 01m or more and less than 50m from the top, the temperature at 18m is 760℃, the temperature at 50m is 740℃, and the temperature found by connecting the two points with a straight line, 50m from the top. Above and maximum BO1tOfll
740℃ over 30m from the bottom, 30m from the bottom
The temperature at a distance of less than 15m and 30m is 740℃, 15
The temperature at the position m is 760°C, the temperature found by connecting the temperatures of the two points with a straight line, and the temperature less than 15m from the maximum Bottom Im is 820°C, which is the upper limit winding temperature (hereinafter referred to as CT), and 5m from the top of hot rolled steel strip
760℃ for less than 760℃, 710℃ for 5m or more and less than 30rn from the top, and 6 for the temperature at 30m.
80℃, and the temperature found by connecting the two points in between with a straight line, 30m or more from the top and the bottom
660℃ over 15m from om, 1 from bottom ω
Temperature at 15 m below 5 m, 680℃, 5
The temperature at position m is 700°C, the temperature found by connecting the two points in between with a straight line, the lower limit of the rolling temperature is 720°C less than 5m from the bottom, and the temperature is controlled and cooled on a run-out table. This is a method for manufacturing a cold-rolled steel sheet for deep drawing using a continuous annealing method, which is characterized by rolling up the steel sheet.

The method of the present invention will be described in detail below.

The present inventors have conducted various studies on a method for producing cold-rolled steel sheets for deep drawing using a continuous annealing method using low carbon AN guild steel.

First, the conventional method described in JP-A No. 51-66219 uses A with a high C content of 0.05% [guild steel is used, instead of soft cold rolled steel sheet, it is used for deep drawing with a high i value. We investigated the manufacturing method of cold-rolled steel sheets. As a result, when the slab heating temperature during hot rolling was as high as 1250°C, the CT was set to 730°C.
However, as stated in the same publication, the value of 1 was around 1.4, which could not satisfy the required material quality for cold-rolled steel sheets for deep drawing.

Next, the present inventors discovered that AΩ with a high C content of 0.05%
Using killed steel? We studied various ways to improve the value and decided to increase the heating temperature of the slab to 1 when hot rolling.
The method of heating at a low temperature such as 050°C is further improved to prevent material deterioration of the T and B parts of the hot rolled steel sheet and to improve the coarse crystal grains of the hot rolled steel strip during high temperature rolling (when pressing the cold rolled steel sheet). In order to prevent the occurrence of an abnormally large orange peel (referred to as "rough skin"), the T and B sections of the ROT hot-rolled coil using the method disclosed in JP-A No. 51-66219 were coated with 20 m to 20 m each on the T and B sections.
We investigated a method that combines the method of rolling up cooling water over a distance of 0 m without spouting it out.

As a result, although an improvement effect was observed in increasing the F value, it was found that there were three major problems.

The first point is T, which is the innermost and outermost part of the hot rolled coil.

Except for each 3 to 7 m of B section, the hot-rolled sheet crystal grains in T, B section (20 m to 200 m) and some areas inside thereof became coarse crystal grains. For the two-point opening, there is no temperature range in which the material of the M part and the avoidance of coarsening of the hot-rolled sheet grains can be compatible.
The three-point openings are T and B, which are the innermost and outermost parts of the hot-rolled coil.
7 values of 20m and 10m for each part are low, and the yield deterioration is large.

It has been found that the method for producing cold-rolled steel sheets for deep drawing using the method disclosed in JP-A-51-86219 in combination with low-temperature slab heating cannot produce cold-rolled steel sheets for deep drawing by continuous annealing.

Therefore, in a method of hot rolling using a low-temperature slab heating method, the present inventors discovered that when rolled up using the method described in JP-A-51-11i8219, hot-rolled plate crystals were observed as described in the same publication. As a result of examining why it was not possible to make hot-rolled coils without coarsening of the grains, we found that in the case of the same publication, the slab heating stage (the contents of the publication, 7-value level,
(estimated to be 1200°C or higher based on the research results of the present inventors) is A, 17. N is dissolved in solid solution, and a large amount of AgN precipitates at the grain boundaries of the hot rolled sheet from the middle of hot rolling to the early stage after rolling up. It is thought that the precipitates prevented abnormal grain growth (coarsening) of the crystal grains of the hot rolled sheet in the high temperature range after rolling.

However, in the case of the inventors' above experiment of low temperature slab heating, Ag in the low temperature slab heating stage.

Most of the N has already precipitated as AIIN, and as a result, from the middle of hot rolling, which suppresses coarse grains, to the early stage after rolling, less AI precipitates at the grain boundaries of the hot-rolled sheet, which causes the formation of grains. It is thought that coarsening occurred easily.

In addition, AgN precipitated at the grain boundaries also during continuous annealing.
It also suppresses the grain growth of recrystallized grains, and it is as low as JP-A-51-66219. It was found that only cold-rolled steel sheets with a certain value could be manufactured.

As a result of the above preliminary experiments, in order to realize the manufacturing method of cold-rolled steel sheets for deep drawing by continuous annealing using AΩ killed steel as material, it is necessary to It has been found that it is essential to find a method that can prevent the coarsening of the hot-rolled sheet crystal grains by a mechanism different from that of 9N, and that also does not reduce the 7 value.

Therefore, the present inventors first conducted various experiments as a basic experiment to find a method for achieving both of the above (1) and (2), and developed a new industrially possible method for preventing grain coarsening of hot-rolled sheets. It has been found that a method of regulating the C content to 0.015% or less is superior.

The reason why the method of regulating the C content to 0.035% or less is highly effective in suppressing coarsening of hot-rolled sheet grains is that by controlling the C content to 0.035% or less, transformation after hot rolling is prevented. As a result, the large α grains are stable and difficult to cause abnormal grain growth, and the abnormal grain growth (coarse and It is thought that this could have prevented the

In other words, there is a new mechanism in which it is possible to prevent abnormal grain growth not by AIN but by large α crystal grains that are generated by transformation after hot rolling, and as a method that can be industrialized, it is possible to reduce the C content to 0.035% or less. succeeded in finding a way to regulate it. Furthermore, this method does not utilize AgN and is a low C method, so it is a method that improves the 7 value of ■.

In addition, the reason why the crystal grain size of α grains that undergo transformation after hot rolling increases by regulating the C content to 0.035% or less is due to the effect of increasing the transformation temperature due to lower C, It is thought that the α grains became large and stable due to the increase in the α grain size during transformation due to the low C content. Furthermore, the reason why it is possible to prevent abnormal grain growth even with large α grains is thought to be because the thermal energy required to grow abnormal grains by eating other large grains adjacent to them is thought to be large. .

Based on the effect of inhibiting abnormal grain growth of crystal grains in hot-rolled sheets by regulating the C content to 0.035% or less obtained in the above basic experiments, cold-rolled steel sheets for deep drawing are manufactured by continuous annealing. Various experiments were conducted on the method, and ■c: o, oog
〜0.035%, ■ heating temperature of slab to 1000℃
~1170℃, and 18 m or more from the top of the hot rolled steel strip in the longitudinal direction and 15 m or more from the bottom of the hot rolled steel strip are RO.
Water injection cooling was performed on the T, and the temperature was 18 m from the top of the hot rolled steel strip.
The temperature at a position 18m or more and less than 50m from the top is 760°C, and the temperature at a position 50m is 740°C, and the temperature found by connecting the two points with a straight line between them is the temperature at the top. 50m or more and maximum fio
740℃ for 30m or more from bottom, 740℃ for 30m or more less than 30m from bottom■
℃, the temperature at a position of 15 m is 760℃, and the temperature found by connecting the two points with a straight line, the maximum Bott.
The upper limit of the winding temperature is 820°C for less than 15m from o■, and 760°C for less than 5m from the top of the hot rolled steel strip.
, 5 m or more and less than 30 m from the top, the temperature at the position 5 m is 710 ° C, the temperature at the 30 m position is 680 ° C, and the temperature is determined by connecting the two points with a straight line. The temperature at 15m or more from the highest bottom is 660℃, the temperature at a position 15m or more less than 15m from the highest bottom is 680℃, and the temperature at 5m is 700℃, and the temperature is determined by connecting the two points with a straight line. Temperature, 720 less than 5m from the bottom
We succeeded in discovering a method for producing cold-rolled steel sheets for deep drawing using a continuous annealing method, which has three main features: the lower limit of the rolling temperature is 100°C, and the rolling is controlled and cooled on an ROT.

C content is an important point as mentioned above,
If it is less than 0.008%, the precipitation rate during overaging treatment will slow down and the aging characteristics will deteriorate, so the lower limit should be set at 0.008%.
008% or more. Furthermore, if the C content exceeds 0.035%, coarsening of the hot-rolled sheet crystal grains tends to occur and the 7 value decreases, so the upper limit was set at 0.035%.

It is difficult to keep Sl to less than 0.003%, and if it exceeds 0.1%, the adhesion of the paint film during painting will deteriorate, so the range of S1 content is 0.003%. %～0
．． 035%.

It is difficult to reduce Mn to less than 0.0596 using normal steel manufacturing methods, and if it is contained in an amount exceeding 0.35%, the f value will decrease significantly, so the Mn content ranges from 0.05% to 0.05%. 0
．． It was set at 35%.

It is difficult to reduce P to less than 0.001% in ordinary steelmaking methods, and if it is contained in excess of 0.10%, the secondary workability will be greatly reduced, so the range of P content is 0.001%. 001%
~0.10%.

It is difficult to reduce S to less than o, oot% in normal steel manufacturing methods, and if it is contained in excess of o, oao%, the decrease in the 7 value will be large, so the S content range is o, ooi%. ~0
．． 030%.

5oi1. A D is an element necessary to keep it precipitated as A47N during the low-temperature slab heating stage during hot rolling, and if it is less than 0.020%, AI will not be present even during low-temperature slab heating.
N re-dissolves into solid solution, and fine AIN precipitates during rolling or continuous annealing, resulting in a decrease in the F value. Also, 0. lO%
Does solid solution strengthening start to become noticeable when it is super contained? Since the decrease in values, etc. becomes large, the range of sof, A O content is 0.0.
The content was set at 20% to 0.10%.

It is difficult to reduce N to less than 0.0005% in a normal steel manufacturing method, and if it is contained in excess of o, ooeo%, the decrease in the 7 value becomes large, so 5oi1. The range of AI content was 0.0005% to 0.0060%.

There is no need to particularly regulate the casting conditions for the slab, and continuous casting or ingot casting may be used.

Hot rolling conditions are an important element as mentioned above. There is no need to particularly regulate the thermal history up to the heating of the slab, and even if the slab is once formed into a cold piece and then inserted into the heating furnace,
It may be inserted into the heating furnace in the form of a hot piece.

The slab heating temperature plays an important role in precipitating Ag and N as AfiN and increasing the F value of the product after continuous annealing, and it is desirable to lower the heating temperature.
If the temperature exceeds 170°C, solid solution of Ag and N increases, making it impossible to obtain the F value required for a steel plate for deep drawing. Also, if the temperature is less than 1000°C, it will not be possible to secure the hot rolling finishing temperature necessary for manufacturing cold rolled steel sheets for deep drawing, so the range of the slab heating temperature should be set to 1.
000°C to 1170°C.

Of course, the hot rolling finishing temperature must be maintained at the A r 3 point or higher, but in order to coarsen the α grains after transformation, which is the method of the present invention for preventing coarsening of hot rolled sheet crystal grains. A high temperature is desirable, but industrially, in the case of low-temperature slab heating, 9
The limit is 60°C. In addition, in the case of the present invention, the limit finishing temperature at which coarse grains do not occur is 890°C as a result of various experiments.
Therefore, the finishing temperature range was 890°C to 960°C.
And so.

As a result of various experiments, the ROT cooling conditions are as follows:
At least 18 m or more from the top of the hot rolled steel strip and the top B
Water injection cooling is performed on the ROT for a distance of 15 m or more from the ottom, and controlled cooling is performed to ensure cooling within the winding condition range of the method of the present invention.

At least 18m from the top and the bottom
In order to perform water injection cooling on the ROT over 15 m, it is necessary to perform hot rolling at high speed in order to secure a FT of 890°C or higher with low-temperature slab heating, and a high FT of 890°C or higher.
This is because water injection cooling is necessary to cool the film to the rolling temperature range of the method of the present invention with a limited ROT length.

Next, it is preferable to cool the material at a temperature of 40° C./see or less within a temperature range from the finishing temperature to 830° C. in order to more reliably generate coarse grains.

It is important to regulate the winding temperature in extremely detail, and as a result of numerous experiments conducted by the present inventors, the material composition and hot rolling conditions were strictly limited, and furthermore, the rolling temperature was 18 m from the top of the hot rolled steel strip in the longitudinal direction. above and L5m or more from the bottom is RO
Water injection cooling was performed on the T, and the temperature was 18 m from the top of the hot rolled steel strip.
The temperature at a position 18m or more and less than 50m from the top is 760°C, and the temperature at a position 50m is 740°C, and the temperature found by connecting the two points with a straight line between them is the temperature at the top. 50m or more and the highest bot
740℃ for 30m or more from TOA+, 740℃ for 30m or more less than 30m from the bottom
℃, the temperature at a position of 15 m is 760℃, and the temperature found by connecting the two points with a straight line, the maximum Bott.
The upper limit of rolling temperature is 820°C for less than 15m from oII, and 76°C for less than 5m from the top of the hot rolled steel strip.
0℃, the temperature at the position 5m or more and less than 30m from the top is 710℃, the temperature at the position 30m is 680℃,
Temperature determined by connecting the temperature of the two points between them with a straight line, 30m or more from the top and 15m from the bottom.
m or more is 660℃, less than 15m from BottoI11, the temperature at 15m or more is 680℃, the temperature at 5m is 700℃, and the temperature found by connecting the two points with a straight line between them is the maximum temperature. The lower limit of rolling temperature is 720°C less than 5m from the bottom, and by controlling cooling and rolling on ROT, we can produce cold rolled steel sheets with excellent deep drawability without coarsening of hot rolled sheet grains. Manufacturing became possible.

When the winding temperature at each position in the longitudinal direction of the hot-rolled steel strip exceeds the upper limit of the temperature in the method of the present invention, the grains of the hot-rolled sheet become coarsened, and the winding temperature at each position in the longitudinal direction of the hot-rolled steel strip increases. is below the lower temperature limit of the method of the invention? Since the value decreases and it becomes impossible to obtain cold-rolled steel sheets for deep drawing, the above restrictions were made.

Cold rolling can be carried out at a cold rolling rate that is normally used for cold rolled steel sheets, and there is no need to limit it in particular, but is it higher? In order to obtain this value, it is preferable that the cold rolling rate is 70% or more.

Continuous annealing may be a continuous annealing method for cold-rolled steel sheets that includes overaging treatment to improve aging properties after recrystallization annealing, as is usually done, but in order to obtain a higher value of 1, annealing is necessary. Preferably, the temperature is 750°C or higher.

(Example) A 4.0 mm hot rolled coil was manufactured under the manufacturing conditions shown in Table 1, cold rolled to 0.80 mm, and the i value of a cold rolled steel sheet manufactured under the continuous annealing conditions shown in Table 1. The results are shown in Table 2.

In order to investigate the 7 values and roughness of the cold rolled steel sheet, we investigated 5 locations in the longitudinal direction of the cold rolled steel strip after temper rolling, and examined the cold rolled steel strip at 5 m from the top of the hot rolled steel strip during hot rolling. Position the steel strip at T1
part, the position corresponding to the position 30m from the top is 12 parts, the position corresponding to the center position is part M, the most Bottom
The position corresponding to the position 30m away from B2, the highest Bott
The position corresponding to the position 5 m from orA was indicated as 81 copies.

Steel 1. Steel 2. Steel 3 was an example of the present invention, and the f value showed a good value over the entire length of the coil, and there was no roughening at all, and an excellent cold-rolled steel sheet for deep drawing was obtained.

Steel 4 is a comparative example with a high C content of 0.055%.

The value of 1 is low, and the deterioration of the T and B portions is particularly large. In addition, although it was mild, rough skin occurred in the M area despite the CT of 710° C., which shows that the method of the present invention is highly effective in reducing C.

Steel 5 is an example of the present invention applied to a deep-drawing tensile strength steel with a tensile strength of 35 kg class with addition of 0.075% P.
The f value showed a good value over the entire length of the coil, and there was no surface roughness, and an excellent tensile strength cold rolled steel sheet for deep drawing was obtained.

Steel 6 is a comparative example in which the slab heating temperature is 1250°C.

The 1 value of the M part was a good value, but the TI.

Severe deterioration of part B1.

Is Steel 7 a comparative example of low-temperature uniform rolling with a rolling temperature of 630°C? The value is completely low. Steel 8 has a rolling temperature of 71
In a comparative example with a uniform rolling temperature of 0° C., the M portion had a good value of 7, but the rl and B1 portions were severely degraded.

Steel 9 is a comparative example with a uniform rolling temperature of 760°C, and the 7 value of the M part was a very good value, but the 12
The skin of parts 1, M, and 82 was so rough that it could not be used as a product at all.

Steel 10 was developed in Japanese Patent Application Laid-Open No. 51-86 in a low-temperature slab heating method.
Applying the rolling method of Publication No. 219, the M part was heated to 711°C.
This is a comparative example (the length of T and B portions rolled up without water injection was 35 m). Although a good F value was obtained, rough skin occurred in 12 parts and B 2 parts, and the product could not be made into a product. This is because the non-water injection part was too long, which was 35 m, and the occurrence of rough skin could not be completely suppressed only by the low C effect of the present application and the winding temperature regulation of the M section.

*1 In near LO-U, 710 indicates the winding temperature of the M section, and U indicates the winding temperature pattern (details are shown below).

U pattern: An example of a CT pattern of the method of the present invention,
CT is controlled to 800℃ without water injection from the top position to 15m from the top, and by water injection cooling from a position 15m from the top to 750℃, gradually and linearly. Lower the CT and set the CT at a position 30m from the top to 7.
10℃, from the position 30m from the top
M part up to 20m from No. 11 at 710℃, maximum BOt
The CT was gradually increased linearly from a position 20 m from tOffl until the CT at a position 8 m from the top was 740°C, and the remaining part up to the bottom was rolled at 760°C.

F pattern: M pattern with uniform winding temperature over the entire length, by applying the winding method of JP-A-51-66219 to the method of low-temperature slab heating, the T and B sections are each 35 m long.
The length was rolled up without pouring water. The CT of the amorphous water cooling section is 805°C at the top, BottoI1
One portion was at 800°C.

(Effects of the Invention) The effects of the present invention have been described in detail above. According to the present invention, it is possible to manufacture cold rolled steel sheets for deep drawing by continuous annealing using low-cost AΩ killed steel. ,
Its industrial value is great.

teenager Reason Man

Claims (1)

[Claims] C: 0.008 to 0.035%, Si: 0.003 to 0.10%, Mn: 0.05 to 0.35%, P: 0.001 to 0.03% by weight. 10%, S: 0.001-0.030%, sol. Molten steel consisting of Al: 0.020-0.10%, N: 0.0005-0.0060%, the remainder unavoidable impurities and iron is made into a slab by continuous casting or ingot method, hot rolled, Pickling,
In a method for manufacturing cold-rolled steel sheets for deep drawing that undergoes a continuous annealing process with cold rolling and over-aging treatment, the heating temperature of the slab is set to 1.
000°C to 1170°C, finish rolling at 890°C to 960°C, and roll the hot rolled steel strip at 18°C from the top in the longitudinal direction.
Water cooling is performed on the run-out table for 15 m or more from the top of the hot-rolled steel strip and 15 m or more from the bottom, and 850°C for less than 18 m from the top of the hot-rolled steel strip.
The temperature at a position of 18 m is 780°C, the temperature at a position of 50 m is 740°C, and the temperature obtained by connecting the two points with a straight line is 740 m or more from the top and 30 m from the bottom. ℃、Most Botto
The temperature at a position 30 m below 30 m and 15 m or more from m is 7.
The temperature at a position of 40℃ and 15m is 760℃, and the temperature found by connecting the two points with a straight line is the maximum Bo.
The upper limit of the rolling temperature is 820°C for less than 15m from the top of the hot rolled steel strip, and 7m for less than 5m from the top of the hot rolled steel strip.
60℃, the temperature at a position 5m or more and less than 30m from the top is 710℃, the temperature at 30m is 680℃, and the temperature found by connecting the two points with a straight line, 30m from the top. More than 1 from the bottom
5m or more at 660℃, less than 15m from the bottom5
The lower limit is 680℃ for the temperature at 15m above m, and 700℃ for the temperature at 5m, and the temperature found by connecting the two points with a straight line, and 720℃ for less than 5m from the bottom. A method for manufacturing a cold-rolled steel sheet for deep drawing by a continuous annealing method, which is characterized by controlling the rolling temperature and rolling the steel plate with controlled cooling on a run-out table.