JPS5861228A - Production of original black plate for ultra thin galvanized steel plate having excellent shape - Google Patents

Abstract

PURPOSE:To obtain a titled black plate having excellent shapes at considerably reduce energy to be consumed in production by using continuously cast materials or capped steel materials and specifying the temp. of hot finish rolling in production stages and the thickness of hot rolled blank materials. CONSTITUTION:The continuously cast slab of the steel contg., by %, <=0.08C, <=0.03 Si, 0.12-0.30 Mn, <=0.030 P, <=0.030 S, <=0.06 Al, and the balance iron and unavoidable impurities and >=10 Mn/s is hot rolled. In this time, the finish rolling is completed at the Ar3 point -700 deg.C, then the steel plate is coiled at 600-450 deg.C to provide a hot rolled steel strip of 1.6-2.3mm. thickness. In succession, the steel strip is cold rolled after descaling by pickling or the like. Here, the limitation of C results in decreased yield strength of the hot rolled plate and improved cold rolling performance. Since this effect is observed in hot rolling below the Ar3 point, the upper limit of the hot rolling is set at the Ar3 point. The temp. for heating slabs is made lower than in the prior art and the thickness of the hot rolled strip is decreased. Thus the original unit of quantity of heating is reduced, and the cold rolling is accomplished in the good finish state advantageously in terms of energy and working efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for manufacturing an original sheet for an ultra-thin galvanized steel sheet with an excellent shape, and in particular, an original sheet for an ultra-thin galvanized steel sheet with little flatness such as edge elongation and belly elongation. This invention relates to a manufacturing method that reduces the amount of energy consumed for manufacturing.

At present, the so-called ultra-thin galvanized steel sheets of O, CO, TO- are processed into products such as corrugated sheets after galvanizing. With sheets, there are problems such as gaps being formed when stacked after forming corrugated sheets, and the specified dimensional accuracy not being achieved after forming, so flattening due to edge elongation and belly elongation of the original sheet for ultra-thin galvanized steel sheets is a problem. High quality requirements have become extremely strict. ◇Figure 1 shows the process of the conventional manufacturing method for ultra-thin galvanized steel sheets, and O! 0.041
A bale that has been hot finish rolled at a high temperature of 3 points or more using open-top rimmed steel with ~O, 10%, rolled at the normal winding temperature (hereinafter referred to as OT), Hot-rolled steel sheets with a temperature of more than 100%, and cold-rolled after pickling, especially about 0'
For thin materials of , AO- or less, the above-mentioned original plate was manufactured in a process of performing Jl1, and then supplied to the plating process.

Explaining the reasons why the above process was adopted in the conventional method, firstly, open ship rimmed steel is used because the base plate for ultra-thinly cut galvanized steel sheets is hardened in the first heat. This is because cold rolling properties deteriorate, so it is preferable to use open-trap mud steel, which is relatively soft.

Next, the hot finish rolling temperature (hereinafter referred to as FDT) is set to Ar
On the contrary, FDT is limited to high temperatures of 3 points or higher.
It was common knowledge in the field of rolling technology that if the temperature of the hot rolled steel sheet falls below the Ar3 point, the crystal grains in the hot rolled steel sheet will become coarser and the quality of the galvanized steel sheet made from this material will become extremely poor. ~by.

Roughly, the rim layer of the steel ingot has a lower C content than the central part of the steel ingot due to the rimming action. This rim layer becomes the end portion of the steel sheet in the width direction by rolling, and the 0 content at this end is significantly lower than that at the center of the sheet, resulting in a difference in the 0 content in the sheet width direction, and therefore Ar 3 The points are also different (because the Ar3 point arises depending on the component), and the Ar8 point at the end
The point is higher than the center.

Therefore, if the steel plate is heated to a temperature based on the Ar3 point in the center, there is a risk that the temperature at the end portions will fall below the Ar5 point, and in that case, crystal grain growth is likely to occur at the end portions. This tendency is further promoted by the fact that the sheet temperature during hot rolling is approximately 50° C. lower at the ends than at the center. If grain growth occurs at the edges, there is a risk that the edge elongation at the edges will increase after cold rolling. Because of the above problems, hot rolling is performed using FDT at a relatively high temperature of 3 or more Ar points.

As for the winding temperature, the winding is usually carried out at a low temperature around sjo°C, but since the material becomes softer at a higher temperature, a particularly thin plated steel sheet may be wound at a high temperature.

In such a rolling method, in order to maintain a predetermined rolling temperature, the lower limit of the possible thickness of the hot-rolled material sheet is about 100 mm, and it cannot be made thinner than this.

As described above, hot-rolled sheets are relatively hard and relatively thick, so the work efficiency is very low in cold rolling. rolling 2
The plate is finished to the specified thickness by repeated rotations.

Furthermore, in such conventional methods, the flatness of the product original plate is poor, and the edge elongation index (mu) of the flatness index is /Q w
m/ym≦mu≦X) m/m, abdominal stretch index (B) is 4
The condition was such that only about IIllII/m≦B≦10 wm/w* could be produced. In addition, the ear elongation index (M) and belly elongation index) are defined as the height of the peak of ear elongation in the 1s diagram is R1 (seagull), and the height of the peak of belly elongation is Ht (M).
(The suffix 1 indicates a winter mountain with an elongated edge and an elongated belly.) Then, the sum of the heights of the elongated peaks per meter (M) in the L direction of the steel plate strip is calculated. Let B be the total height of
It is expressed as l=1.

On the other hand, in recent years, the requirements for shape quality in terms of flatness of base sheets for ultra-thin galvanized steel sheets have been strict, and M≦IOam
/m, B≦3■/m, very strict requirements are now being issued.

The following measures can be considered as countermeasures to the above problems.

(1) In order to obtain flatness, it is possible to use continuous casting material with uniform composition or capped steel material, but since these are harder than open top rimmed steel material,
During cold rolling, the rolling load increases, and the rolling pressure distribution in the radial direction during cold rolling is concentrated at the edges of the sheet width due to roll bending, and the original sheet tends to stretch at the edges, making it extremely difficult to obtain a sheet with excellent flatness. becomes difficult. Furthermore, HIT (Ho
rs@Pow@r Hours-p@r Ton)
The consumption of cold rolling energy per roll increases, wear of the rolls occurs during cold rolling, and a slip phenomenon occurs. For this reason, the frequency of changing rolls increases, and as a result, production efficiency decreases.

(II) To solve the problem in (1), it is possible to reduce the thickness of the hot-rolled steel plate to, for example, about 1.0-7.4 to lower the reduction rate in the cold rolling process. However, in order to reduce the thickness of a hot-rolled sheet, it is necessary to increase F over the entire width in the sheet width direction.
In order to bring the DT to a temperature of 3 points or higher, it is necessary to increase the heating temperature of the slab and reduce the unit weight of the slab. Even if this was done, the temperature at the edge of the plate would drop below the Mr5 point, grain growth would occur, and the edge elongation would increase, often resulting in poor flatness. Furthermore, by increasing the heating temperature and reducing the unit weight of the slab, even if a product with improved flatness to some extent is obtained, it will be rolled due to biting.
There is a problem of poor appearance.

(3) Increasing the OT may also be considered as a method of softening and improving flatness, but this poses the problem of an extreme drop in pickling efficiency.The purpose of the present invention is to solve the above problems. An object of the present invention is to provide a method for manufacturing an ultra-thin galvanized steel sheet with excellent flatness, which can solve the problems and produce the original sheet with significantly reduced energy consumption. .

The gist of the present invention is as follows.

(1) C:≦o, os%, S1:≦0.0.3-%'
, Mu + 0. /Co~O', JO%, P:≦o,o
, io%%3+≦a030%.

Steel with Mu71≦o, ob%, balance F and unavoidable impurities, and Mu/S: ≧10 is made into a slab by continuous casting, and when this is hot rolled, %A1”
Finish rolling is completed at a temperature of 3 points or less, 700°C or higher, and then coiled at a temperature of 600°C to 30°C.
J. A 3-thick hot-rolled steel strip, which is then subjected to de-schooling treatment such as pickling, and then cold-rolled.
A method for manufacturing ultra-thin galvanized steel sheets with excellent shapes.

(Ri Os o, o da ~ 0.0 de%,
)in! 0. Ko0 ~ OJO%.

P:≦o, o4Io−, S! ≦o, oqos, remainder r and unavoidable impurities, and Mxv'8:
≧'' is made into a capped steel ingot, which is made into a steel billet by blooming rolling, and when hot rolling this steel billet, the unevenness is 3 points or less, @100°C or more. Finish rolling was completed at a temperature of 400"C to 0.5"C, followed by coiling at a temperature of 400"C to 30C to form a hot rolled steel strip of 7.4s IB-1 and 3-thickness, followed by de-snarling treatment such as pickling. A method for producing an original sheet for an ultra-thin galvanized steel sheet having an excellent shape.

The present invention uses a steel material obtained by continuous casting and blooming rolling of a capped steel ingot having a composition in the above-mentioned range, and
By hot rolling the DT at a temperature between 3 points and 700°C, it is possible to coarsen the grains even if the sheet is wound using normal OT, making it possible to soften the hot-rolled sheet. This makes it possible to make the thickness of the hot-rolled sheet thinner than before, and it is also possible to produce an ultra-thin original sheet for galvanized steel sheets with excellent flatness even by performing cold rolling once.

The material of the original plate, which will be described below in detail regarding the present invention, must have uniform components and must be soaked to ensure good flatness. First, we will discuss the significance of limiting the range of chemical components in continuously cast materials.

〇:≦o, b1%～～～N When C increases beyond 0.01%, the °Mr3 point becomes low, and accordingly, it becomes necessary to lower the hot rolling temperature in order to achieve grain growth. . However, when the hot rolling temperature is lowered, the hot rolling resistance of the slab increases (as a result, the required hot rolling horsepower increases, making it difficult to obtain a hot rolled fill of the required thickness. If the temperature is not sufficiently lowered to 3 points or less, the hardness distribution in the width direction of the hot-rolled coil will be higher at the center, and edge elongation will occur in the cold-rolled coil.

Furthermore, as explained later regarding 'ffDT,
If hot rolling is carried out at a temperature below 115 points,
As the 0 content decreases to 0.01% or less, the yield strength of the hot rolled sheet decreases and the cold rollability improves.

In view of the above, the upper limit of the amount of O is set at 0.01%.

Mn Wealth 0. /ko~0. JO% Mu/8: ≧10 In is at least 0 to prevent hot embrittlement due to S.
．． /Co1 is necessary, but adding more than O,SO% is not necessary and will actually increase the product cost.

Furthermore, if Mn/8 is less than 10, hot rolling will cause hot rolling embrittlement and the width edges of the hot rolled steel strip will be prone to cracking, so Mu/8 should be 10 or more. .

"P" +: O', mixed '0' lyo, many, 6. Hot soup board. 0.030 because it increases the yield and deteriorates cold rolling properties.
% or less.

S: ≦0.030% If S exceeds 0.030%, surface flaws due to hot embrittlement will occur in the product, so it should be kept at 0.030% or less.

Sl: ≦0.03% Sl is 0.03% in order to provide good galvanizing properties to the original plate.
It is necessary to keep it below 0.3%.

Mu! :≦0.01. % Conventional continuous casting technology requires a certain amount of sludge to prevent blowholes in the product slab. However, with the improvement of continuous casting technology, although mue is necessary until solidification of the product slab, it is no longer necessary for the solidified slab. If molten steel is oxidized by air or refractories during the casting process, the number is 15! However, improvements in air oxidation prevention technology and refractory materials have made it possible to obtain slabs of excellent quality even with low mulch content. Therefore, it is not necessary to add mulch in an amount exceeding 0.06%.

Next, we will discuss the significance of limiting the range of ingredients in the capped steel used in the present invention.

0: 0.0*~0.01% Capped steel has mu! Since N is not present, it is softer than continuous cast material. However, if the zero amount increases beyond 0.09 arc, the hardness of the hot rolled sheet increases and the cold rollability deteriorates. On the other hand, if it is less than 0.041%, a good min-axis carbon cannot be obtained, and therefore surface defects or pinholes due to puta-holes, inclusions, etc. may occur. Therefore o: o, o
We regret that p~0.0.

81: trao・Sl is the amount of traoe as in normal capped steel.

)In: 0. -〇～0. ! rO% 1 (n/S: ≧IO Mn is at least O in order to prevent hot embrittlement caused by S and to further normalize the forming axis.
o-〇Sorry is necessary. However, even if the amount is greater than o or zos, these effects cannot be further enhanced and the cost of the product will increase, so the upper limit is set to 0 or IO-.

Furthermore, if n/8 is smaller than 10, hot embrittlement occurs during hot rolling, and the width edges of the hot rolled steel strip tend to crack, so Mn/S is set to 70 or more.

P richness≦0.0410% P has the effect of increasing the hardness of the hot rolled sheet, thereby degrading the cold rolling properties of the hot rolled sheet, so 10, o4to
The attack shall be below.

S: ≦0.0 θ% Since S inhibits the rimming action and makes the surface quality of the product poor, it is necessary to suppress it to 0% or less.

Next, the hot rolling conditions of the present invention will be explained.

The manufacturing process of the original sheet for ultra-thin galvanized steel sheet according to the present invention is as follows:
As shown in FIG.
By rolling for 1 hour at a temperature of 3 points or less, the plate thickness is reduced to Jm.
-7,4- is made into a hot-rolled sheet, and after being rolled up with OT under normal exposure, it is subjected to descaling treatment such as washing, and then cold-rolled with 4 units of 1 to form the above-mentioned plated original plate. be.

Therefore, the significance of specifying the hot rolling conditions in the present invention will be explained below.

FMs 115 points ~ 00℃ First the present invention (1
) is relatively hard compared to rimmed sea bream or capped steel due to the presence of IM, so it must be made soft. As this method, the upper limit of the amount of O is specified, and the FDT is set to 3 points to 00''C.
Regarding the basis for specifying the upper limit of T, if hot rolling is completed with 115 points or less @ I (vJ ferrite) + r (austenite) 1 region, the hot rolled structure will be present immediately after exiting the final stand. However, immediately after that, r recrystallizes, and cold rolling further progresses, causing r to α transformation. When this is rolled up, crystal grain growth occurs due to self-annealing, resulting in fine and uniform crystal grains. A is simply strain-annealed 5t
rain -AnnI&ling). That is, after being subjected to hot working under light reduction (approximately 3 to 71%) at the final stand, annealing progresses when it is wound up, and the crystal grain size becomes extremely coarse. Therefore, the hot-rolled sheet becomes a mixture of fine grains in which r has been transformed to α and grains in which α has become extremely coarse due to strain-annealing, but it has a coarse structure as a whole.

In this process, the present inventors newly discovered the following fact.

That is, Fig. 3 shows the relationship between C content and yield strength of hot rolled sheet.
The results are shown for those with FDT of 113 points or less (kukuO°C) and those with Mr of 3 points or more (tbθ°C). As shown in Figure 3, the yield strength of a hot-rolled sheet hot-rolled at 113 points or less has a strong correlation with the C violet of the steel sheet, and as the amount of C decreases, the yield strength of the hot-rolled sheet decreases. , improved cold rolling properties. However, when hot rolling is carried out at the A point of 3 or higher, there is no significant correlation between the yield strength and the C content, and CfIk
It was found that the degree of softening is very small even if the amount is reduced.

Further, when hot rolling is performed at a temperature of FDT 113 or lower, the hardness distribution in the width direction of the hot rolled sheet is slightly hard at the ends and soft at the center, as shown by ash. This means that a cold-rolled sheet that is superior in flatness, especially edge elongation, can be obtained compared to the case where hot rolling is carried out by normal FDT at a temperature higher than the Arcs point. Furthermore, when manufacturing thin hot-rolled sheets suitable for manufacturing ultra-thin cold-rolled sheets, the heating temperature of the slab is increased to maintain the FDT at the unevenness point of 8 or higher over the entire width of the hot-rolled steel strip as in the conventional method. At the same time, the slab must be smaller than usual, which is very disadvantageous in terms of energy consumption and work efficiency.

On the other hand, according to hot rolling performed at low FDT,
Easy and economical FDT of slabs across the entire width.
The temperature can be adjusted at 13 points or less. Zarani 11
When performing hot finish rolling at a temperature of 3 points or less, the heating temperature of the slab can be changed to t, sso℃ in the case of conventional high FDT.
For ~/, 300℃, /100℃~l is sufficient, and the heating temperature can be lowered too much, so the heating amount basic unit can be reduced. When hot rolling with FDT, the temperature can be uniformly maintained at a temperature of 115 points or less across the width of the slab, and the hot rolled sheet has uniform crystal grains and is softened. Since it is possible to make the thickness thinner than that in the conventional method, cold rolling properties are improved, and by performing cold rolling,
Mu≦10m/! It is possible to produce a galvanized steel sheet material with an excellent flatness of II, B≦j; #/m.

Based on the above points, the upper limit of FDT is set to A r3 point.

Next, regarding the basis for the lower limit of FDT, if FDT is lower than necessary, the load of hot rolling will increase, making it impossible to obtain the specified hot-rolled plate thickness, and the OT will inevitably become low temperature. This is because crystal grain growth due to self-annealing of the hot coil does not occur.

OT i 600℃～Da kO℃ OT is 1. As the copper strip is wound at a high temperature, the crystal grain size increases and becomes soft due to self-annealing, but the extent of this change is due to the OT inside the copper strip and at the ends. I knew it would be different.

Regarding this point, as shown in Fig. DA (as is clear from the relationship between 3T and the yield strength distribution in the width direction of the copper strip, when the OT is high (6 tO℃), the inside of the copper strip becomes soft, but the edge Air cooling reduces the degree of softness and increases the difference in hardness in the ring direction.On the other hand, CT is low (!rdeθ℃, z4Io℃
, 0° C.) and self-annealing within the steel strip is suppressed, making it slightly hard, and as a result, the difference in hardness in the width direction becomes smaller. As a result, the shape of the cold-rolled sheet is improved if the difference in yield strength in the width direction is small. Zara OT is 400
If the temperature exceeds .degree. C., the pickling properties of the hot-rolled sheet become poor and the pickling efficiency decreases. Particularly in the case of thin hot-rolled coils, a decrease in pickling efficiency has a large effect in terms of a decrease in workability and an increase in manufacturing costs.

However, when the OT temperature becomes lower than jθ°C, the self-annealing effect of the hot-rolled coil weakens, crystal grain growth does not proceed, and the hot-rolled sheet becomes hard. Therefore, OT is defined as 400°C to ajo°C.

Thickness of hot rolled steel strip! 1.4 - J+w Generally, the rolling point when obtaining an ultra-thin steel plate by cold rolling is as follows.

In other words, even if the material of the hot-rolled sheet is uniform in one direction,
As the reduction ratio in cold rolling increases, the rolling load increases -1.As a result, the rolling pressure distribution in the width direction during cold rolling is concentrated at the edges in the width direction due to roll bending. This tends to cause elongation, making it extremely difficult to obtain a material with excellent flatness.

In this regard, the graph in FIG. 5 shows that the cold reduction rate has no effect on the re-stretching deformation of the cold-rolled sheet in continuous casting materials. It can be seen that as the rolling reduction increases beyond 90%, the re-stretching increases.

Therefore, when the thickness of the hot-rolled plate is thicker than 2.3, the rolling reduction ratio in cold rolling increases, so re-stretching increases, and the load in cold rolling increases, so that the specified It may become impossible to roll the plate to a certain thickness, or the rolling speed may not be sufficiently increased due to chatter. On the other hand, /jm
If it is thinner than the thickness, hot rolling efficiency and descaling efficiency such as acidity will be significantly reduced, which will be economically disadvantageous in terms of increasing the total manufacturing cost of the process from hot rolling to cold rolling. .

Therefore, the thickness of the hot-rolled sheet is defined as 6-6.

Examples of the present invention will be described below in comparison with comparative examples.

EXAMPLE Various slab slabs were manufactured by continuous casting of molten steel refined in an oxygen bottom blowing converter. The composition of the slab slab is as shown in Table 1, and in the comparative example, slabs that met the composition range of the present invention and slabs that did not meet the composition range of the present invention were used. Table 1 also includes comparative examples of manufacturing from rimmed steel slabs by the conventional ingot-blowing rolling method.

These slabs were hot rolled under the hot rolling conditions shown in Table 1. In the hot rolling of the comparative example, the FDT was set within the conditions of the present invention of 115 to 700°C, and the conventional mura was used.

The test was carried out at a temperature above the point. Then, after descaling, cold rolling was performed at the rolling reduction ratio shown in Table 1.

In addition, in cold rolling, q, 3, and 6 stand continuous cold rolling mills were each used once (l Roll), and for the production of original sheets with extremely fine finished sheet thickness, the rolling mill was 1.4
1, j' and 6-stand continuous cold rolling mills, and then an example in which the rolling was carried out once on a 3-stand continuous cold rolling mill (2 Roll) was also added.

While continuing to unwind the cold rolled steel strip on the unwinding line/
Re-stretching and flattening were measured as the flatness of the steel plate on a surface plate at a rate per ton/location. Re-stretching These are also shown in Table 1.

A7θ~/ko is an example in which conventional high-temperature FDT rolling was performed using a continuously cast slab with a composition within the composition range of the present invention. Both the ears and abdomen are large.

A1.3 is a slab whose Of exceeds the upper limit according to the present invention, and Al4I is a slab whose Mli1 is the same but exceeds the upper limit. Therefore, these slabs were heated with low FDT according to the present invention. The edge elongation of the cold-rolled sheet was 10~/
This is a slight improvement, but it is extremely worse than the example of the present invention. This is thought to be due to the fact that the amount of C and silica increased, resulting in finer grains and the hardness of the hot-rolled sheet, resulting in poor shape.

For Al, although the component range and hot rolling temperature of the slab are within the range of the present invention, the thickness of the hot rolled sheet exceeds the upper limit of the thickness range defined by the present invention. This was cold-rolled at the same time, but the flatness of the cold-rolled sheet was poor. The reason for this is thought to be that due to the higher rolling reduction, the edges in the width direction of the sheet were elongated due to bending of the cold rolling work rolls, resulting in increased edge elongation.

Mu/Todoroki and Mu/ri were hot-rolled by low-temperature FDT and high-temperature FDT, respectively, using conventional open-top rimmed steel billets, but the flatness of the cold-rolled products for both Tsuba was superior to that of non-electrode. Therefore, the edge elongation is large even in the case of O/G which was rolled with low FDT. The reason for this is that the elongation is due to the high cold reduction rate and the rim layer at the edges in the width direction, making the edges soft. It can be said that it cannot compete with wood.

Example 2 Molten steel refined in an oxygen bottom blowing converter was formed into a capped steel ingot and bloomed to produce a slab of steel. The composition of the slab is as shown in Table 2 as a ladle analysis value, and for the comparative example, one whose oJl was within the range of non-inventive components and one whose oJl was outside the range of components were used. ii these slabs! Each was hot-rolled under the hot-rolling conditions shown at 2tM.

In the comparative example, the FDT was set to 113 points to 700 points under the conditions of the present invention.
It was carried out at a temperature higher than the concentration 3 and the temperature 3 points in °C.

After pickling, cold rolling was performed at the rolling reduction ratio shown in Table 2. Note that cold rolling was carried out once or twice as in Example 1.

A10 ~ / Roll is a capped steel whose composition is within the composition range of the present invention and subjected to conventional high temperature FDT EE rolling, but cold rolling was performed using capped steel whose composition is within the composition range of the present invention.
No matter which method was used, both the ear extension and belly extension became larger.

A/? is an example in which a slab with a C content greater than the upper limit of the present invention was used, but the flatness deteriorated because the hot rolled sheet became hard.

A/4' is an example in which the component amount and hot rolling temperature are within the range of the present invention, but the thickness of the hot rolled sheet exceeds the range specified in the present invention, and this is However, the flatness of the obtained cold-rolled sheet was poor.

The reason for this is as described above.

Next, for extremely thin galvanized steel sheets of o, iz or less, for example, from the viewpoint of cold rolling mill capacity or workability,
S shows an example in which a steel plate with excellent flatness could be manufactured even if further tandem rolling was performed after the second tandem cold rolling.

In addition, depending on the application where processing is severe, cold rolling or cleaning may be omitted and annealing may be added.

As explained in detail above, the present invention is a method of heating a slab of continuous cast material or capped steel material having a specified composition with FDT at a temperature of 3 points to 700°C. The original sheet for ultra-thin galvanized steel sheets has a shape that cannot be obtained using manufacturing methods using rimmed steel materials, that is, excellent flatness due to edge elongation and belly elongation.
It can be manufactured with a significant reduction in the energy required for manufacturing.

[Brief explanation of the drawing]

Fig. 1 is a process diagram illustrating the manufacturing process of a base plate for thin galvanized steel sheets by the method of the present invention and a conventional method. Sashimi diagram, No. J! i! ! I is a graph showing the influence of Ckk and FDT on the yield strength of a hot-rolled sheet, and the second figure is a graph showing the influence of FDT on the yield strength along the width direction of a hot-rolled sheet.
Figure 3 is a graph showing the influence of cold rolling ratio on edge elongation of cold rolled sheet. Patent Applicant Kawasaki Steel Co., Ltd. Representative Patent Attorney Mura 1) Politics 1. , clear direction C formula @ne order C quantity (wj (1 m)

Claims (1)

[Claims] L C:≦0.01%, Sif≦0.03%l M
2R: 0, /Col 0.30%, P:≦0.030
%, S: ≦0.030%, Mul=≦o, ob%
, the remainder is y and unavoidable impurities, and Mu /
Steel with Sz≧/θ is made into slabs by continuous casting,
When hot rolling this, finish rolling is completed at a temperature of 00°C or higher with unevenness of 3 points or less, and then at a temperature of 400°C or higher! 0
A pole with an excellent shape, which is produced by winding it into a 3-thick hot-rolled steel strip at a temperature of ℃, followed by descaling treatment such as pickling, and then cold rolling. Method for glazing original sheets for thin galvanized steel sheets. & O: o, olI-o, ot%, Kn: 0
6 0~0. SO attack. P:≦0.04!0%, 8:≦0.04LO%
, the remainder r and unavoidable impurities, and Mu
/ S+≧10 steel is made into a cap-do ingot.
This is made into a piece by blooming rolling, and when hot rolling this steel piece, finish rolling is completed at a temperature of 70θ℃ or higher at 3 points or less of Ar, and then coiling at a temperature of 400℃ to 4130℃. An original sheet for an ultra-thin galvanized steel sheet with an excellent shape, characterized in that it is made into a hot-rolled steel strip with a thickness of 6-1.3 m, followed by pickling cape descaling treatment, and then cold-rolled. manufacturing method.