JPH11302883A - Cold rolling for stainless steel sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a steel sheet having high brightness and high surface quality in spite of rolling at a high rolling speed by executing wiping of the steel sheet surface with steam at least prior to rolling in a final pass. SOLUTION: The austenitic stainless steel sheet is cold rolled by a reverse rolling mill using an oil-in-water type emulsion oil. The steam is injected to the steel sheet surface after one pass and after two passes in such a manner that the steel sheet temp. before the second pass attains >=65 deg.C and that the steel sheet temp. before the third pass attains >=75 deg.C. The wiping of the steel sheet surface is executed by the steam prior to rolling in at least the final pass, by which the oil-component and worn powder deposited on the steel sheet surface are removed. As a result, the purposes may be achieved and further edge cracking, chatter marks and sheet breakage may be prevented. The raw liquid of the emulsion oil is prepd. by using mineral oil, synthetic hydrocarbon, etc., having a low viscosity as a base oil and adding synthetic esters thereto.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cold rolling a stainless steel sheet using an emulsion oil in a reverse rolling mill, and a method for cold rolling an austenitic stainless steel sheet capable of preventing occurrence of edge cracks and chatter marks. To a hot rolling method.

[0002]

2. Description of the Related Art Cold rolled stainless steel sheets generally require high surface gloss. Stainless steel has high deformation resistance and is easy to work harden. Therefore, a Sendzimir mill equipped with a small-diameter work roll that can obtain a high rolling pressure and has a small amount of rolling oil introduced between a steel sheet and a work roll (hereinafter referred to as a roll bite) during rolling is used.

[0003] In rolling in a Sendzimir mill, a water-insoluble rolling oil (hereinafter, referred to as neat oil) using a low-viscosity mineral oil as a base oil or a rolling oil obtained by emulsifying the same has been used as a rolling oil. However, the Sendzimir mill has a problem that the rolling mill has a complicated structure with 20 rolls and the roll diameter is as small as 50 to 80 mm, so that the rolling speed is restricted and the productivity is low.

[0004] In recent years, in order to improve productivity, high gloss rolling using a tandem mill having a large work roll diameter has been attempted.

Japanese Patent Application Laid-Open No. 2-110195 discloses a low-viscosity rolling oil for tandem mills, and Japanese Patent Application Laid-Open No. 4-118101 discloses a cold tandem mill using a high-viscosity fine-grained oil-in-water emulsion oil. A rolling method is disclosed.
However, although these methods can improve the rolling efficiency, a large amount of oil pits are generated on the surface of the steel sheet after rolling, so that it is not possible to obtain the same high glossiness as when rolling using neat oil in a Sendzimir mill. Can not.

[0006] Recently, a six-stage UC mill with a work roll diameter of 80 to 120 mm, which has higher productivity, a simpler structure, and a better shape control function than the Sendzimir mill, has been developed, and has a high speed rolling speed of 600 m / min or more. Have been tried.

[0007] When a low-viscosity mineral neat oil is used as a rolling oil in a UC mill, cooling and lubrication are insufficient due to high-speed rolling, resulting in seizure flaws and ignition at the time of a steel strip breaking accident. There were problems such as ignition of rolling oil. When using a high-viscosity neat oil with high lubricity,
An increase in the amount of oil introduced into the roll bite causes a problem of a decrease in glossiness.

[0008] Therefore, it has been practiced to use a common oil-in-water emulsion oil (hereinafter simply referred to as emulsion oil). However, although the fear of an ignition accident is resolved,
Since the cooling property is increased, the rolling oil viscosity on the roll bite becomes higher than that of the neat oil, the oil film becomes thicker, the oil pit area increases, and sufficient gloss cannot be obtained. Furthermore, there was a problem that uneven attachment of the emulsion oil to the steel plate or roll and an oil pattern (irregular gloss) due to partial adhesion of a viscous scum in which abrasion powder was taken into the emulsion oil.

[0009] Particularly in winter, when the outside air temperature is low, the temperature of the steel sheet after rolling tends to be low, and the scum in which the abrasion powder is mixed with the emulsion oil adhering to the rolls of the rolling mill cools down, becomes more viscous, and becomes glossy. The degree of deterioration and uneven gloss increase. The problem was remarkable in the rolling of a ferritic stainless steel sheet requiring gloss.

[0010] On the other hand, in the rolling of austenitic stainless steel, in addition to the above problems, rolling induces work-induced martensite (hereinafter simply referred to as martensite), which causes work hardening, making rolling more difficult. It is known that this martensite is more likely to be generated as the rolling is performed at a lower temperature.

As a method of suppressing the formation of martensite, Japanese Patent Application Laid-Open No. 64-21013 discloses a method of rolling by increasing the temperature of the steel sheet in the initial pass to 50 ° C. or more and 250 ° C. or less. The publication discloses a method for uniformly increasing the steel sheet temperature to around 100 ° C. in a short time.

However, in these methods, since the steel sheet is cooled immediately before rolling by the rolling oil used, it is difficult to keep the temperature of the steel sheet at a predetermined temperature. In particular, when an emulsion oil is used, the temperature of the steel sheet is lower than that during neat oil rolling due to a difference in cooling ability, and the effect is not sufficiently exhibited. As a countermeasure, it is conceivable to use the rolling oil at a high temperature, but if it is too high, there is a problem that seizure occurs in an intermediate pass.

Further, in the rolling of austenitic stainless steel, there is a problem that ear cracks and chatter marks are easily generated as compared with ferritic stainless steel. Ear cracks occur when the total draft exceeds about 50%. If it becomes too severe, it will cause the plate to break. Therefore, it is necessary to reduce the tension and perform rolling at a light reduction rate, and the number of rolling passes increases.

In the case of rolling with emulsion oil, ear cracks extend to the inside and to chatter marks as compared with neat oil rolling. In particular, in a reverse type rolling mill, the cooling of the steel sheet becomes remarkable during acceleration and deceleration in each rolling pass, so that ear cracks and chatter marks are remarkably generated. This is further encouraged in winter when the outside air temperature is low, due to the low material temperature of the initial pass.

FIG. 1 is a view showing the appearance of chatter marks generated on an austenitic stainless steel sheet.

When chatter marks are generated, the rolled material vibrates and the rolling becomes unstable, and the chatter marks on the surface of the material to be rolled become stripes of about twice the thickness in the width direction of the sheet, thereby deteriorating the surface quality. Moreover, when it is remarkable, it leads to a plate break. Chatter marks are characterized in that they are more likely to be generated as the rolling reduction is increased in the latter half of the rolling pass in which the total rolling reduction exceeds 50% and the rolling speed is 300 m / min or more, as in the case of the edge cracks. The only countermeasure is light rolling or low-speed rolling, which significantly reduces rolling efficiency.

As described above, in the cold rolling of stainless steel in a reverse type rolling mill, high glossiness, uneven gloss, cracks in the ears, chatter marks, etc. occur, so that the high speed at a high speed of 600 m / min or more is required. The current situation is that rolling cannot be performed efficiently.

[0018]

SUMMARY OF THE INVENTION An object of the present invention is to provide a reverse type rolling mill for cold rolling of stainless steel sheets using emulsion oil, even when rolling at a high rolling speed of 600 m / min or more. The purpose of the present invention is to provide a cold rolling method capable of obtaining a steel sheet of high surface quality.More specifically, for a stainless steel sheet requiring high gloss represented by ferritic stainless steel, Provides a cold rolling method that can suppress the decrease in glossiness and unevenness due to abrasion powder on the surface, and a cold rolling method that can further prevent edge cracks, chatter marks, and sheet breakage for austenitic stainless steel sheets. It is to be.

[0019]

The gist of the present invention relating to a method of cold rolling a stainless steel plate is as follows.

(1) A method of cold-rolling a stainless steel plate with a reverse type rolling mill using an oil-in-water emulsion oil, wherein at least before the rolling in the final pass, the surface of the steel plate is wiped with steam to obtain an oil content. And a method for cold-rolling a stainless steel plate, wherein abrasion powder is removed.

(2) A method of cold rolling an austenitic stainless steel sheet by a reverse rolling mill using an oil-in-water emulsion oil, wherein the temperature of the steel sheet before the second pass is 6
After 1 pass and 2 passes, steam is sprayed onto the steel sheet surface so that the temperature of the steel sheet before the third pass becomes 75 ° C. or more at 5 ° C. or more, and at least before the rolling in the final pass, the steam is sprayed on the steel sheet surface. A cold rolling method for austenitic stainless steel sheets, wherein wiping is performed to remove oil and wear powder attached to the steel sheet surface.

The inventors of the present invention have found that, when an emulsion oil is used in high-speed rolling, the gloss of the steel sheet decreases due to a decrease in the temperature of the steel sheet, the scum mixed with wear powder adheres to the steel sheet or roll, and the oil pattern (glossiness) due to the partial adhesion thereof. Survey of the occurrence of irregularities)
First, in order to prevent the occurrence of ear cracks, chatter marks and the like of the austenitic stainless steel sheet, the actual conditions of these defects were first investigated in detail. As a result of conducting various experiments based on the results of the actual state survey, the following findings were obtained.

A. Regarding glossiness and unevenness of glossiness of stainless steel sheet Although the amount of emulsion oil adhered to the surface of the steel sheet after rolling is extremely small, the amount of abrasion powder adhered is large, and the amount of adhered oil increases in the second half pass, and the scum viscosity is increased. Will be higher.

In the conventional method of wiping the rolling oil before winding into a coil, the scum having increased viscosity cannot be sufficiently removed. When the wiper is a tube type or a roller type, abrasion powder easily accumulates in front of the wiper, and what passes therethrough becomes a steel plate stain or a pushing flaw during rolling. Wiping with steam is effective for such a problem.

This is because the use of steam increases the temperature of the scum and the steel plate during wiping and lowers the viscosity of the scum adhering to the oil, thereby improving oil drainage.

The wiping with steam may be performed at least before the final pass.

Further, since the temperature of the steel sheet increases, the temperature of the steel sheet on the entry side of the next pass also increases, the viscosity of the emulsion oil decreases, and the oil pits are reduced, thereby increasing the glossiness.

B. Ear Cracks and Chatter Marks of Austenitic Stainless Steel Sheet (a) Ear cracks and chatter marks are basically the same phenomenon. Due to continuous shear deformation.

(B) Periodic shear deformation occurs when the temperature of the steel sheet is low and the amount of martensite exceeds 10%. However, the temperature of the steel sheet on the inlet side in the second pass is 65 °
If the temperature of the steel sheet on the third pass is 75 ° C. or more, the amount of martensite does not exceed 10%, and ear cracks and chatter marks are reduced to a level that does not pose a practical problem.

(C) In order to secure the inlet-side steel sheet temperature in the second pass, it is conceivable to use the processing heat by strongly reducing the pressure in the first pass. However, when the rolling is performed strongly, abrasion powder is generated more frequently, and uneven gloss is likely to occur. In winter, when the temperature of the steel sheet on the input side in the first pass is low, a rolling reduction of 30% or more is required, which exceeds the rolling capacity of the rolling mill. Therefore, it is necessary to increase the temperature of the steel sheet by other means.

(D) Preheating by radiant heat or induction heating of the steel sheet on the first pass entrance side can increase the temperature of the steel sheet after rolling. However, when the oil content of the emulsion oil adheres to the dry steel sheet, the temperature of the steel sheet increases. When it is high, uneven adhesion is apt to occur, and galling or gloss unevenness, which is a kind of seizure, tends to occur. (E) To heat the steel sheet to which the rolling oil has adhered after one-pass rolling, steam is better than radiant heat or induction heating. This is because the method of radiant heat or induction heating causes deterioration of the oil content, resulting in a decrease in lubricity and a decrease in gloss. However, when steam is used for wiping, even if the oil component is altered, most of the oil component is removed from the surface of the steel sheet, so that a decrease in lubricity and a decrease in glossiness are unlikely to occur.

FIG. 2 is a diagram showing a microstructure of a longitudinal section of a steel sheet in a portion where chatter marks are generated. As shown in the figure, the surface has a saw-tooth structure inclined at about 45 to 50 degrees in the thickness direction from the surface of the steel sheet. This is due to the formation of martensite, which is hardened, the deformation resistance is increased, and the normal layered compressive deformation is not generated, so that a shear deformation like a fault occurs. The portion where the shear deformation reaches the steel sheet surface becomes a chatter mark. It has been clarified that the chatter mark is not caused by the vibration phenomenon of a general rolling mill, but is caused by the phenomenon that the plastic working becomes unstable due to periodic shear deformation.

FIG. 3 is a graph showing the relationship between the viscosity of the emulsion oil, the friction powder ratio, and the wear powder / (wear powder + oil content) obtained by experiments. This is the result of using an emulsion oil having a crude oil viscosity of 4, 7, and 12 cSt at 40 ° C. and measuring the viscosity while variously changing the amount of abrasion powder in each emulsion oil. It is getting bigger. This result indicates that the viscosity of the scum increases in the latter half of rolling because the amount of wear mixed into the oil increases. Therefore, to prevent the viscosity of the scum attached to the steel sheet from increasing during rolling,
It can be seen that it is necessary to reduce wear powder mixed in the emulsion oil.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The reasons for limiting the conditions specified in the cold rolling method of the present invention will be described below.

First, the reason why the rolling oil is wiped with steam at least before the final pass to remove oil and abrasion powder attached to the steel plate will be described.

The wiping is performed to remove rolling oil for winding and to remove wear powder mixed in the rolling oil.

The reason for using steam for wiping is that when steam is sprayed on a rolled steel sheet, the temperature of the steel sheet rises instantaneously. This is because removal of oil and abrasion powder is easier than wiping by a method. Therefore, it is effective in suppressing plate dirt, uneven gloss, and indentation flaws. Also, since the temperature of the steel plate rises,
The temperature of the steel sheet on the entry side in the next pass also increases, and the oil film thickness of the roll bite becomes thin, which leads to a reduction in oil pits and an increase in gloss.

In the case of the conventional tube-type and roller-type wipers, abrasion powder easily accumulates in front of the wipers, and those that have passed through the wipers become stains on the steel sheet and push flaws during rolling.

The reason why wiping is performed at least before rolling in the final pass is that abrasion powder on the surface of the steel sheet accumulates and increases in the second half pass, so that the wiping effect is more effective in the second half pass. This is to reduce oil pits that have been generated by rolling.
Therefore, even if wiping with steam is performed in the first half pass of rolling, wear powder increases if not performed in the second half pass, and the effect is small. Needless to say, wiping with steam is more effective if performed in another pass other than before the final pass.

Note that the term "before the final pass" means a period from the end of the rolling of the second pass from the final pass to the final pass. It is preferable to perform the rolling after the rolling of the second pass from the last pass and before the winding. This is because the wiping of the rolling oil for winding, which has been conventionally performed, becomes unnecessary. In addition, after the rolling of the second pass from the final pass is completed, normal wiping is performed and winding is performed. Then, after the steel sheet is rewound for rolling in the final pass, wiping is performed until the final pass. Is also good. In this case, wiping before normal winding is required. However, there is an advantage that oil and wear powder remaining in normal wiping can be removed by wiping with the next steam.

Next, the reasons for limiting the conditions defined by the cold rolling method for austenitic stainless steel sheets will be described in detail.

The reason for injecting steam after the first and second passes so that the steel sheet temperature before the second pass is 65 ° C. or more and the steel sheet temperature before the third pass is 75 ° C. or more is as follows. is there.

The reason why the steam is injected into the steel sheet surface after one pass and after two passes is to increase the temperature of the steel sheet before rolling in two and three passes to suppress the formation of martensite, and to scum on the steel sheet surface. In order to remove.

Although a method using radiant heat or induction heating can be considered to increase the temperature of the steel sheet, such a heating method involves:
Deterioration occurs in the oil attached to the steel sheet surface, causing a decrease in lubricity and a decrease in gloss. However, the use of steam does not have such an adverse effect.

Martensite is apt to occur when the temperature of the steel sheet on the entry side of the rolling mill is low. Particularly, when the steel sheet on the entry side of the second pass is less than 65 ° C., the temperature of the steel sheet on the entry side of the third pass is 7 ° C.
Rolling at less than 5 ° C. becomes remarkable, and the amount of martensite generated in such a case exceeds 10%, and ear cracks and chatter marks are likely to occur. Therefore, steam is injected onto the steel sheet surface such that the temperature of the steel sheet on the entering side in the second pass is 65 ° C. or more and the temperature of the steel sheet on the entering side in the third pass is 75 ° C. or more. By doing so, the generation amount of martensite can be suppressed to less than 10%, and ear cracks and chatter marks are reduced to a level that does not pose a practical problem.

Injection of water vapor is performed after one pass and after two passes, but is preferably performed before winding after one pass or two passes. This is because the usual wiping before winding is unnecessary. In addition, 1
Ordinary wiping may be performed after the pass rolling to wind up, and then steam may be injected after unwinding for the second pass rolling. Similarly, the injection of water vapor after two passes may be before or after winding after two passes.

The temperature of the steel sheet before rolling in the first pass may be room temperature. Usually, the rolling reduction in the first pass is about 10 to 25%, and the amount of martensite generated is 8% or less, and there is no problem. Of course, it is preferable to suppress the generation of martensite even in the first pass rolling, and it is also conceivable to preheat the steel sheet on the first pass side. However, in the first pass, no rolling oil is adhered, and if such a steel sheet is preheated and emulsion oil is adhered, uneven adhesion is likely to occur, and galling and gloss unevenness, which are a kind of seizure, are caused. Easy to occur. On the other hand, after one pass, even if wiping is performed, some oil remains on the surface of the steel sheet, and even if the emulsion oil is applied after spraying steam to increase the temperature of the steel sheet, adhesion unevenness does not occur. . Therefore, in the present invention, 1
Inject steam after the pass.

In the case where steam wiping is performed before winding after rolling in the first pass, the temperature of the steel sheet on the incoming side in the second pass is set to 65 ° C. or more, and the temperature of the steel sheet before winding is set to 70 ° C. or more. What is necessary is just to become. This is because there is a maximum decrease in the steel sheet temperature of 5 ° C. after the rolling in the first pass and before the start of the second pass. Similarly, in order to set the temperature of the entry side steel sheet in the third pass to 75 ° C. or higher, the temperature of the steel sheet before winding after the second pass rolling may be set to 80 ° C. or higher.

In order to increase the temperature of the steel sheet on the entry side in the second pass, it is possible to reduce the pressure in the first pass without resorting to the wiping of steam. However, when the rolling is performed strongly, abrasion powder is generated frequently, and it is easy to cause uneven gloss. In winter, when the temperature of the steel sheet on the input side in the first pass is low, a rolling reduction of 30% or more is required, which exceeds the rolling capacity of the rolling mill. Therefore, it is substantially difficult.

The wiping of the rolling oil with steam at least before the final pass is the same as the reason described above.

Next, the steam used in the present invention will be described. Here, the steam is not special, the pressure is about ² to 7 kg / cm ² , and the temperature is 100 to 150 ° C.
It is. In addition, the flow rate is 30
It may be about 200 l / min. The nozzle is desirably installed so as to face the steel sheet surface more vertically than in the traveling direction. By doing so, it becomes easy to raise the temperature and remove oil and wear powder. Therefore, it is better that the distance between the nozzle and the steel plate is as short as possible, and it is more efficient to arrange the nozzles in a plurality of rows.

Next, the composition and properties of the emulsion oil used in the present invention will be described. The composition and properties of the rolling oil used in the present invention are not particularly limited, but the following can be used.

The stock solution of the emulsion oil is obtained by adding a low-viscosity mineral oil, a synthetic hydrocarbon or the like to a base oil and adding a synthetic ester thereto. For example, any one of fatty acids having 10 to 18 carbon atoms such as lauric acid and palmitic acid and 1 to 1 carbon atoms.
8, a monoester with any of the alcohols, a monoester and / or a diester and / or a triester of the above-mentioned fatty acid with a polyhydric alcohol such as trimethylolpropane,
Further examples include diesters of dibasic acids such as adipic acid and the above-mentioned alcohols. The compounding amount of the synthetic ester is 50 in saponification value of the whole emulsion oil crude oil.
The viscosity range of the stock solution is 7 cSt to 15 cSt at 40 ° C. The concentration when dispersed in water is preferably 5 to 20%, and the average diameter of the oil particles is preferably in the range of 1.5 to 5 μm. In addition,
The rolling oil temperature during use is preferably from 40 to 50C.

[0054]

EXAMPLES The effects of the present invention will be described in detail below with reference to examples. Diameter 100mm, surface roughness Ra0.1
3 μm, work roll made of SKD11 and diameter of 3
Using a 4Hi reverse rolling mill equipped with a 50 mm backup roll, rolling was performed in 9 passes under the rolling conditions shown in Tables 2 and 3 using the materials to be rolled shown in Table 1.

[0055]

[Table 1]

[0056]

[Table 2]

[0057]

[Table 3]

The rolling oil had the composition and properties shown in Table 4 below.
Seed oil was used. Wiping with steam was performed under the four conditions shown in Table 5. As a comparative example, wiping by a tube type was also performed. Cold rolling was performed according to a combination of rolling conditions, rolling oil and wiping conditions shown in Tables 6 to 8.

[0059]

[Table 4]

[0060]

[Table 5]

[0061]

[Table 6]

[0062]

[Table 7]

[0063]

[Table 8]

The wiping using the rolling oil as the emulsion oil was performed under various wiping conditions shown in Table 5 only for the wiping use paths shown in Table 6. The wiping before the winding after the other passes was performed by the air method (E in Table 5). All wiping with steam was performed before winding after each rolling.

The rolled steel sheet was visually inspected for uneven gloss and seizure. For the SUS430 material, the amount of adhered oil, wear powder / (wear powder + oil content), and gloss at a measurement angle of 60 °: Gs60 were measured.

For the SUS304 material, the degree of occurrence of ear cracks and the width of occurrence of chatter marks at the location where the frequency of occurrence of ear cracks and chatter marks is highest, the amount of martensite measured by a magnetic ferrite meter, and the amount of martensite were measured. did. Further, Tables 6 to 8 show the presence / absence of sheet breakage in rolling up to the final 9 passes and the occurrence paths according to the following criteria. In addition, the measurement is performed on the fracture path when the plate is broken by the final pass, and the other values are the values of the final pass.

(Attached oil amount) ○: less than 200 mg / m ² , □: 200 to 400,
Δ: More than 400 (wear powder / oil amount ratio) ○: less than 25%, □: 25 to 50%, ▲: more than 50% (gloss) ○: 430 or more, □: 400 to 430, ▲: less than 400 ( (Inappropriate quality) (approximate gloss unevenness) ○: Not confirmed, □: Slight, no problem in quality,
▲: Remarkable and unsuitable quality (approaching indentation flaw) ○: No occurrence, □: Slight occurrence (within allowable range), ▲: Remarkable occurrence (defective) (degree of seizure flaw) ○: No occurrence, □: Slight Occurrence (within allowable range), ▲: Remarkable occurrence (defective) (depth of ear crack) ○: No occurrence, □: Minor occurrence (within allowable range), ▲: Remarkable occurrence (defective) (Chatter mark width) ：: Not confirmed, □: Slight (1 to 3 mm), no quality problem, ▲: Remarkable (5 mm or more), unsuitable for quality (martensite amount) ○: Less than 10%, □: 10 to 11% (within allowable range) ),
：: 11% or more (presence or absence of sheet break) ：: No occurrence, ▲: Occurrence Regarding the rolling of the SUS430 material of the present invention, the wiping of the rolling oil in the eighth pass, ie, one pass before the final pass, was performed. It can be seen that when the treatment is carried out with steam, oil and abrasion powder adhering to the rolled steel sheet can be removed well, high glossiness is maintained, and uneven gloss, push-in flaws and seizure flaws do not occur.

Further, after the first and second passes, steam is injected, and the steel sheet temperature at the time of coil winding in the first pass is 70 ° C. or more, and the steel sheet temperature at the time of coil winding in the second pass is 80 ° C. or more. In the example of the SUS304 material according to the present invention, the amount of the generated martensite is small, and there is no occurrence of ear cracks and chatter marks, or it is extremely light. It can be seen that rolling can be performed. Further, if the wiping eight passes before the last pass is also performed with steam, the unevenness of gloss can be further improved.

[0069]

According to the method of the present invention, even when a stainless steel plate is rolled at a high rolling speed of 600 m / min or more, a steel plate with high gloss and high surface quality can be obtained stably. Further, with respect to the austenitic stainless steel sheet, occurrence of edge cracks, chatter marks, sheet breakage, and the like can be suppressed.

[Brief description of the drawings]

FIG. 1 is an external view of a striped chatter mark generated on a SUS304 cold-rolled steel sheet.

FIG. 2 is a view showing a microstructure of a cross section in a rolling direction of a chatter mark generating portion.

FIG. 3 is a graph showing the relationship between the ratio of wear powder adhering to the surface of a steel sheet after rolling in a rolling pass and the viscosity.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B21B 45/02 330 B21B 45/02 330

Claims (2)

[Claims] 1. A method for cold rolling a stainless steel plate with a reverse rolling mill using an oil-in-water emulsion oil, wherein at least before the rolling in the final pass, the surface of the steel plate is wiped with steam to obtain an oil content and A method for cold rolling a stainless steel sheet, which comprises removing abrasion powder. 2. A method for cold rolling an austenitic stainless steel sheet by a reverse rolling mill using an oil-in-water emulsion oil, wherein the steel sheet temperature before the second pass is 65 ° C. or more and the steel sheet before the third pass. After the first and second passes, steam is sprayed onto the steel sheet surface so that the temperature becomes 75 ° C. or higher, and at least before rolling in the final pass, the steam is wiped on the steel sheet surface to remove oil adhering to the steel sheet surface. And a method for cold rolling an austenitic stainless steel sheet, which comprises removing wear powder.