JP2009220130A - Method of manufacturing rolled metal strip and method of manufacturing metal strip material using the rolled metal strip - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a rolled metal strip which is suitable for producing a metal strip material containing extremely fine crystal grains in an industrial scale with existing equipment. <P>SOLUTION: A first rolling step of manufacturing a second coil-shaped metal strip 9 from a first coil-shaped metal strip 3 by cold rolling and a second rolling step of manufacturing a third coil-shaped metal strip 15 from the second coil-shaped metal strip 9 are performed. By deciding the cold draft in the first rolling step and the number of the metal strips 7 and the cold draft in the second rolling step so that the rolling equivalent strain of the third coil-shaped metal strip becomes ≥3.8, the third coil-shaped metal strip 15 is made into the rolled metal strip. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a rolled metal strip having a rolling equivalent strain of 3.8 or more, and a metal strip material having ultrafine crystal grains having an average crystal grain size of 2 μm or less using the rolled metal strip. It is about how to do.

  A metal material having ultrafine crystal grains having an average crystal grain size of 2 μm or less has mechanical properties such as toughness, ductility and fatigue strength as compared with a metal material having large crystal grains (average crystal grain size of about 10 to 30 μm). Excellent characteristics. A metal material having such ultrafine crystal grains can be used for small lots and various types of products by rolling into a metal strip having a relatively wide dimension in the width direction and a relatively thin dimension in the thickness direction. It becomes possible. Patent Documents 1 to 5 show conventional methods for producing a metal strip material having such ultrafine crystal grains.

  Patent Document 1 discloses a method for producing a hot-rolled steel strip having ultrafine grains by applying a large strain to a steel plate or slab by hot rolling while controlling the temperature and the rolling reduction.

  Patent Document 2 discloses a method of manufacturing a steel strip having an ultrafine ferrite structure by repeating hot rolling and rapid cooling of a hot slab.

  Patent Document 3 discloses a method of manufacturing a cold-rolled steel sheet having an ultrafine grain structure by cold rolling and annealing a slab to which an alloy element is added or the addition amount of the alloy element is controlled.

  Patent Document 4 discloses a method of manufacturing a steel material having an ultrafine grain crystal structure by performing hot rolling and giving a large strain.

In Patent Document 5, a laminated plate obtained by joining and laminating front ends of a plurality of metal plates whose surfaces have been cleaned is rolled to a predetermined plate thickness, and this process is repeated a plurality of cycles to obtain an ultrafine structure. A method of manufacturing a metal plate having the same is disclosed.
Japanese Patent Laid-Open No. 11-152544 JP 2005-169454 A JP 2004-250774 A JP 2004-346420 A JP 2000-73152 A

  However, in the techniques of the cited references 1 and 2, a relatively thick steel plate (slab) is introduced in order to obtain a strain for forming an ultrafine grain crystal, and a large strain is caused by hot rolling, so that the surface of the steel plate is cracked. Is likely to occur. In addition, there is a problem that distortion is eliminated by a high temperature during hot rolling.

  Further, in the technique of the cited document 3, since the material prepared with the chemical components must be melted and refined, and in the technique of the patent document 4, a special rolling facility is required to perform the hole-type rolling. Manufacturing cost is excessive. In particular, in the technique of Patent Document 4, since the rolling finish width of the obtained ultrafine-grained metal strip is small, it is not suitable for the use of a wide variety of small lots, or when it is manufactured in a wide width and cut to the required width The manufacturing cost is excessive compared to

  In addition, although the technique of patent document 5 performs cold rolling, in addition to repeating lap rolling, since it takes the effort of the adhesion | attachment work before rolling and the cleaning of the lamination | stacking surface of a cut plate, manufacturing cost is large. Become. In addition, there is a problem that the pressure bonding at the boundary between the stacked plates becomes insufficient in the last lap rolling. Furthermore, the rolling shown in Patent Document 5 is not practical because it is not suitable for mass production because it is intended for cut sheets rather than strips.

  The objective of this invention is providing the manufacturing method of the rolled metal strip suitable for producing the metal strip material which has an ultrafine crystal grain on an industrial scale using the existing installation.

  Another object of the present invention is to provide a method for producing a rolled metal strip suitable for practically producing a metal strip material having ultrafine crystal grains.

  Another object of the present invention is to provide a method for producing a metal strip material capable of producing a metal strip material having ultrafine crystal grains on an industrial scale using existing equipment.

  Furthermore, the objective of this invention is providing the manufacturing method of the metal strip material which can manufacture the metal strip material which has an ultrafine crystal grain practically.

The present invention is intended to improve a method for producing a rolled metal strip having a rolling equivalent strain of 3.8 or more by rolling. In the present specification, the rolling equivalent strain is defined by the following equation. In this equation, ri is the rolling reduction (%) during the i-th rolling, and n indicates the number of rolling.

  In the manufacturing method of the present invention, the first rolling process and the second rolling process are performed. First, in the first rolling process, after cold rolling the metal strip drawn from the first coiled metal strip, in which the metal strip is wound in a coil shape, with a cold rolling roll, The latter metal strip is wound into a coil shape to produce two or more second coil metal strips. As the metal strip, metal materials such as iron, iron alloy, copper, copper alloy, aluminum, aluminum alloy, titanium, and titanium alloy can be used. The metal strip has a long shape extending in the longitudinal direction, a thickness dimension of about 0.05 mm to 4 mm, and a width dimension that is several hundred to several thousand times larger than the thickness dimension. . In the second rolling step, two or more metal strips drawn from the two or more second coiled metal strips produced in the first rolling step are stacked and cold clad rolling is performed by a cold rolling roll. Then, the cold-clad rolled metal strip is wound into a coil shape to produce a third coil-shaped metal strip.

  In the present invention, the cold rolling reduction in the first rolling step, the number of the two or more metal strips in the second rolling step, and the cold rolling reduction are expressed by the equivalent rolling strain of the third coiled metal strip. The third coil-shaped metal strip is determined to be 3.8 or more and is a rolled metal strip.

  The rolled metal strip manufactured in this way has a rolling equivalent strain of 3.8 or more. When this is annealed near the recrystallization temperature, a metal strip material having ultrafine crystal grains having an average crystal grain size of 2 μm or less is obtained. A metal strip material having ultrafine crystal grains having an average crystal grain size of 2 μm or less is a metal strip material having an average size of crystal grains as a structural unit of 2 μm or less. In addition, in the state of a rolled metal strip having a rolling equivalent strain of 3.8 or more, when ultrafine crystal grains having an average crystal grain size of 2 μm or less are formed, the above-described annealing may not be performed.

  In the present invention, since two or more metal strips are rolled and rolled, and the strips are pressure-bonded to each other, the thickness of the crimped strip after rolling is more than that of a single plate rolled at the same reduction ratio. Can keep thick. For example, when a strip having a thickness of t1 and t2 is clad and rolled at a reduction ratio r [%] to a thickness of tc, a strip having a thickness of t1 is simply rolled at a reduction ratio r. In comparison, the plate thickness is increased by t2 (1-r / 100). That is, the thickness of the two strips having the same thickness, which are rolled and pressed by 50%, is the same as the thickness of the original strip, and the thickness does not become so thin after rolling. Therefore, according to the present invention, a metal strip having a relatively small thickness dimension is used as an input material, and it is equivalent to rolling necessary to obtain ultrafine crystal grains only by combining general cold rolling and cold cladding rolling. While maintaining the strain, it is possible to produce a metal strip material having ultra-fine crystal grains having a plate thickness comparable to that of the charged metal strip and having a relatively wide width as long as the rolling equipment permits. Therefore, it is possible to obtain a metal strip material having ultrafine crystal grains in a small lot and a variety of uses such as a spring material for electronic parts.

  In the present invention, cold rolling and cold clad rolling can be performed using general existing equipment without using large-scale rolling equipment such as hot rolling or melting and refining equipment such as addition of alloy elements. By simply combining with the above, a metal strip material having ultrafine crystal grains (or a rolled metal strip and a rolled metal strip having a rolling equivalent strain of 3.8 or more) is obtained from a commercially available standard metal strip material. be able to. Therefore, a metal strip material having ultrafine crystal grains can be manufactured with existing equipment, and the manufacturing cost can be reduced. Further, since it becomes possible to produce a metal strip material having ultrafine crystal grains on an industrial scale, the metal strip material having ultrafine crystal grains can be practically produced.

  Either the cold rolling or the cold clad rolling may be performed first. When performing cold clad rolling first, in the first rolling step, two or more metal strips drawn from two or more first coiled metal strips wound in a coil shape. After the plates are stacked and cold-clad-rolled by a cold rolling roll, the metal strip after the cold-clad rolling is wound into a coil shape to produce a second coil-shaped metal strip. In the second rolling step, the clad-rolled metal strip drawn from the second coil-shaped metal strip is cold-rolled by a cold rolling roll, and then the cold-rolled metal strip is coiled Winding to produce a third coiled metal strip.

  In this case, the number of the two or more metal strips in the first rolling step and the cold reduction rate and the cold reduction rate in the second rolling step are 3 equivalent to the rolling equivalent strain of the third coiled metal strip. .8 or more should be determined.

  Moreover, when performing cold rolling previously, you may perform cold rolling again after cold clad rolling. In this case, a third rolling step is further performed after the second rolling step. In the third rolling step, the cold-rolled metal strip drawn from the third coil-shaped metal strip is cold-rolled by a cold rolling mill, and the cold-rolled metal strip is coiled. To produce a fourth coiled metal strip. The cold reduction rate in the first rolling step, the number of the two or more metal strips in the second rolling step, the cold reduction rate, and the cold reduction rate in the third rolling step are the fourth coiled metal. The fourth coil metal strip may be a rolled metal strip by setting the strip equivalent strain to be 3.8 or more.

  When implementing the manufacturing method of the metal strip material which has the ultrafine crystal grain mentioned above, you may make it the structure which performs cold clad rolling twice. By performing the cold clad rolling twice, even when the thickness of the metal strip material having ultrafine crystal grains after annealing is increased, a large rolling equivalent strain can be applied. For example, when cold rolling is performed in the first rolling process and cold clad rolling is performed in the second rolling process, the second rolling process and the third rolling process are performed as follows after the first rolling process is completed. Perform the process. In the second rolling step, two or more metal strips drawn from two or more second coiled metal strips are stacked, cold-rolled by a cold rolling mill, and then cold-clad rolled. Two or more third coiled metal strips are manufactured by winding the metal strip in a coil shape. In the third rolling step, two or more metal strips drawn from two or more third coiled metal strips are stacked, cold-rolled by a cold rolling mill, and then cold-clad rolled. A fourth coiled metal strip is manufactured by winding the metal strip in a coil shape. When performing the first to third rolling steps, the cold rolling reduction in the first rolling step, the number of metal strips in the second rolling step, the cold rolling reduction, and the third rolling The number of the two or more metal strips in the process and the cold reduction ratio are determined such that the equivalent strain to rolling of the fourth coiled metal strip is 3.8 or more, and the fourth coiled metal strip May be a rolled metal strip.

  When cold clad rolling is performed in the first rolling process and cold rolling is performed in the second rolling process, the first to third rolling processes are performed as follows. In the first rolling step, two or more metal strips drawn from two or more first coiled metal strips wound in a coil shape are stacked and cooled by a cold rolling roll. After the intermediate clad rolling, the metal strip after the cold clad rolling is wound in a coil shape to produce two or more second coiled metal strips. In the second rolling step, two or more metal strips drawn from two or more second coiled metal strips are stacked, cold-rolled by a cold rolling mill, and then cold-clad rolled. A third coiled metal strip is manufactured by winding the metal strip in a coil shape. And in a 3rd rolling process, after cold-rolling the metal strip after the said clad rolling pulled out from the said 3rd coiled metal strip with a cold rolling roll machine, the metal strip after cold rolling Is wound into a coil shape to produce a fourth coiled metal strip. When performing these first to third rolling steps, the number of the two or more metal strips in the first rolling step and the cold rolling rate, the number of the two or more metal strips in the second rolling step And the cold rolling reduction ratio and the cold rolling reduction ratio in the third rolling step are determined so that the rolling equivalent strain of the fourth coiled metal strip is 3.8 or more, and the fourth coiled metal strip May be a rolled metal strip.

  Furthermore, after performing the cold clad rolling in the second rolling step and further performing the cold rolling in the third rolling step, the following second to fourth rolling steps are performed after the first rolling step is completed. To implement. In the second rolling step, two or more metal strips drawn from two or more second coiled metal strips are stacked, cold-rolled by a cold rolling mill, and then cold-clad rolled. Two or more third coiled metal strips are manufactured by winding the metal strip in a coil shape. In the third rolling step, two or more metal strips drawn from two or more third coiled metal strips are stacked, cold-rolled by a cold rolling mill, and then cold-clad rolled. A fourth coiled metal strip is manufactured by winding the metal strip in a coil shape. And in a 4th rolling process, after cold-rolling the metal strip after the said cold clad rolling pulled out from the 4th coil metal strip with a cold rolling roll machine, the metal strip after cold rolling The plate is wound into a coil shape to produce a fifth coiled metal strip. When performing the first to fourth rolling steps, the cold rolling reduction in the first rolling step, the number of the two or more metal strips in the second rolling step, the cold rolling reduction, the third rolling The number of the two or more metal strips in the process, the cold reduction ratio, and the cold reduction ratio in the fourth rolling process are set so that the rolling equivalent strain of the fifth coiled metal strip is 3.8 or more. The fifth coil metal strip may be a rolled metal strip.

  Cold rolling or cold clad rolling performed in each rolling step can be performed at room temperature. However, when the cold rolling and / or cold clad rolling performed in each rolling process is performed by heating the rolling object to a temperature lower than the recrystallization temperature, the ductility of the metal strip to be rolled while maintaining the strain is increased. Therefore, cold rolling and / or cold clad rolling can be performed with less pressure than when rolling at room temperature. Moreover, when the rolling object is heated to a temperature lower than the recrystallization temperature and cold clad rolling is performed, the adhesion of the metal strip after the clad rolling can be increased while maintaining the strain. For example, when the first and second rolling steps described above are performed, at least one of the first rolling step and the second rolling step, cold cladding rolling and / or cold rolling is performed at a recrystallization temperature. The rolling target can be heated to a temperature lower than that. When the first to third rolling steps are performed, cold cladding rolling and / or cold rolling is performed in at least one of the first rolling step, the second rolling step, and the third rolling step. Can be performed by heating the rolling object to a temperature lower than the recrystallization temperature. Furthermore, in at least one of the first to fourth rolling steps, cold clad rolling and / or cold rolling can be performed by heating the rolling target to a temperature lower than the recrystallization temperature. The recrystallization temperature varies depending on the material or the rolling reduction.

  In order to increase the ductility of the metal strip that is rolled while maintaining the strain and perform the rolling with less pressure, instead of performing the rolling by heating the rolling object as described above to a temperature lower than the recrystallization temperature. Moreover, you may add the process of cooling, after heating a metal strip to the temperature below recrystallization temperature between each rolling process. For example, when the first and second rolling steps are performed, the step of cooling after heating the metal strip to a temperature lower than the recrystallization temperature between the steps of the first rolling step and the second rolling step. Just do it. Further, when the first to third rolling steps are performed, at least one between the steps of the first rolling step and the second rolling step and between the steps of the second rolling step and the third rolling step. Between the two steps, the metal strip may be heated to a temperature lower than the recrystallization temperature and then cooled. Furthermore, when implementing the 1st thru | or 4th rolling process, between the process of a 1st rolling process and a 2nd rolling process, between the process of a 2nd rolling process and a 3rd rolling process, and 3rd What is necessary is just to implement the process which cools, after heating a metal strip to the temperature below recrystallization temperature between at least 1 process between the processes of a rolling process and a 4th rolling process.

  As mentioned above, although the case where the manufacturing method of the rolling metal strip with a rolling equivalent strain of 3.8 or more was the subject of the invention was described, the subject of the present invention is the production of the metal strip material having ultrafine crystal grains after annealing. Of course, a method may be used. In that case, a rolled metal strip having a rolling equivalent strain of 3.8 or more manufactured by the method for manufacturing a rolled metal strip of the present invention may be heated and annealed near the recrystallization temperature. Thereby, a metal strip material having ultrafine crystal grains having an average crystal grain size of 2 μm or less can be manufactured.

  In the method for producing a metal strip material having ultrafine crystal grains according to the present invention, the coiled metal strip produced in the final rolling step (for example, the third rolling in the case of performing the first to third rolling steps). A metal strip material having ultrafine crystal grains can be produced by annealing the fourth coil metal strip produced in the process as a rolled metal strip. However, annealing may be performed before the rolled metal strip is wound into a coil shape as a rolled metal strip in the final rolling step, and the annealed metal strip may be wound into a coil shape. If it does in this way, the coil-shaped metal strip material which has an ultrafine metal grain can be obtained.

  In addition, when the ultrafine crystal grains having an average crystal grain size of 2 μm or less are formed on the rolled metal strip itself produced by the method for producing a rolled metal strip of the present invention, the annealing as described above is not performed. Also good. In this case, a rolled metal strip having a rolling equivalent strain of 3.8 or more can be used as it is as a metal strip material having ultrafine crystal grains having an average crystal grain size of 2 μm or less.

  To produce a rolled metal strip wound in a coil shape with a rolling equivalent strain of 3.8 or more from a metal strip wound in a coil shape, by appropriately combining cold rolling and cold clad rolling. Therefore, a metal strip material having ultrafine crystal grains can be manufactured with existing equipment, and the manufacturing cost can be reduced.

  Hereinafter, embodiments of a method for producing a rolled metal strip having a rolling equivalent strain of 3.8 or more and a method for producing a metal strip material having ultrafine crystal grains according to the present invention will be described. FIGS. 1A and 1B are diagrams illustrating a manufacturing process of the first example in the embodiment of the present invention. FIG. 2 is a cross-sectional view in which the cross section in the width direction of the metal strip obtained in each step of FIGS. 1A and 1B is enlarged in the thickness direction. In the first embodiment, cold rolling is performed using the rolling process shown in FIG. 1A as the first rolling process. In the rolling process of FIG. 1A, a coiled metal strip 3 (first coiled strip) in which a metal strip 1 made of stainless steel (SUS430) is wound in a coil shape is introduced, and an arrow 4a. The metal strip 1 is pulled out from the coiled metal strip 3 by the supply roller 4 rotating in the direction of. The drawn metal strip 1 continuously moves in the direction of the arrow D1 and passes through the rolling roller 5 that rotates in the direction of the arrow 5a. Rolling by the rolling roller 5 is performed cold (room temperature), and a commonly used cold rolling mill is used for the rolling roller 5. The metal strip 1 that has passed the rolling roller 5 becomes a cold rolled metal strip 7. The cold-rolled metal strip 7 is continuously moved in the direction of arrow D1 and wound in a coil shape by a winding machine (not shown) to form a coil-shaped metal strip 9 (second coil-shaped metal strip). Become. The coiled metal strip 9 is made into two coiled metal strips in order to carry out a second rolling process described later. In this example, such cold rolling is performed several times.

  Next, cold clad rolling using the rolling process shown in FIG. 1B is performed as the second rolling process in the first embodiment. In the rolling process of FIG. 2, the two coiled metal strips 9, 9 produced in the rolling process (first rolling process) of FIG. The rolled metal strips 7 and 7 are pulled out from the metal strips 9 and 9, respectively. The drawn rolled metal strips 7 and 7 are continuously moved in the direction of the arrow D2 while being overlapped, and pass through the rolling roller 11 that rotates in the direction of the arrow 11a. The clad rolling by the rolling roller 11 is also performed cold (room temperature), and a general cold rolling roller is used as the rolling roller 11. The cold-rolled metal strip 7 that has passed through the rolling roller 11 becomes a cold-clad rolled metal strip 13. The cold-clad rolled metal strip 13 continuously moves in the direction of the arrow D2 and is wound into a coil by a winding machine (not shown) to form a coil-shaped metal strip 15 (third coil-shaped metal strip). It becomes. In this example, such cold clad rolling is performed in one or two passes.

  The coiled metal strip 15 constitutes an example of a rolled metal strip before annealing in the method for producing a metal strip material having ultrafine crystal grains according to the present invention. Moreover, the coil-shaped metal strip 15 becomes a metal strip material having the ultrafine crystal grains of the present invention through an annealing process (not shown). In addition, you may implement an annealing process, before winding the cold clad rolling metal strip 13 and making it the coiled metal strip 15. FIG. In that case, an annealing step may be provided between the rolling roller 11 and a winding machine (not shown) in FIG. If it does in this way, the metal strip material which has the ultrafine crystal grain after annealing can be made into a coil shape.

In the first embodiment, the rolling reduction in each of the first and second rolling processes is determined so that the rolling equivalent strain of the coiled metal strip 19 is 3.8 or more. That is, the sum of the rolling equivalent strain obtained by rolling in the first rolling step and the rolling equivalent strain obtained by rolling in the second rolling step (total rolling equivalent strain) is 3.8 or more. Each reduction ratio in the first and second rolling steps is determined. Specifically, as shown in FIG. 2, in the first rolling process, the thickness of the metal strip 1 before cold rolling is 4.0 mm, and the cold rolled metal strip 7 after cold rolling is The rolling reduction r1 is determined so that the plate thickness is 1.0 mm. The rolling reduction r1 in this case is 75%. In the second rolling step shown in FIG. 1B, the rolling reduction r2 is determined so that the two cold-rolled metal strips 7 and 7 have a thickness of 0.25 mm after cold clad rolling. . In this case, the rolling reduction is 87.5%. Although not shown in the table, the width of the metal strip 1 is 150 mm. Further, a metal strip having a thickness of 1.0 to 5.0 mm, such as the metal strip 1, is a material having a general thickness obtained by a cold rolling reroll manufacturer.

When the rolling equivalent strain RS is calculated from the reduction ratio ri using the above equation, the rolling equivalent strain RS1 in the first rolling step is 1.60, and the rolling equivalent strain RS2 in the second rolling step is 2.40. The total rolling equivalent strain RSt (RS1 + RS2), which is the sum of these rolling equivalent strains, is 4.00, and a condition for obtaining a metal strip material having ultrafine crystal grains with an average crystal grain size of 2 μm or less (rolled metal before annealing) The condition corresponding to the rolling equivalent strain RS ≧ 3.8 of the strip can be satisfied. Table 1 shows the relationship between the rolling reduction and rolling equivalent strain.

Table 2 shown below shows the relationship between the rolling reduction and the equivalent strain when the rolled metal strip having the equivalent rolling strain RS ≧ 3.8 is manufactured by performing the lap rolling which is the prior art of the present invention five times. Is shown.

  Comparing the first example (Table 1) and the prior art (Table 2), both the rolling equivalent strains satisfy the condition of RS ≧ 3.8. However, while the conventional technique (Table 2) performs lap rolling as many as five times, in the first embodiment of the present invention, it is only necessary to perform cold rolling and cold cladding rolling once. Therefore, if the first embodiment (Table 1) is used, the manufacturing cost can be reduced as compared with the prior art (Table 2). Further, in the prior art (Table 2), the plate metal after the lap rolling is cut in half, and the process of lap rolling is repeated to treat the plate metal in the state of the first embodiment ( In Table 1), since it can be handled in the state of a coiled metal strip, the manufacturing process can be simplified, and mass production becomes possible. Furthermore, in the manufacturing method of the first embodiment, as the strain to be given to generate ultrafine crystal grains, the strain due to normal rolling before and after the clad rolling is actively used, and the repeated lap rolling shown in the prior art is used. In this way, it does not take time and effort to roll over and over again. In addition, in this embodiment, since the reduction ratio of cold rolling after clad rolling is relatively large at 88%, the adhesion of the clad crimping surface is also improved compared to conventional lap rolling.

  3 (A) and 3 (B) are diagrams for explaining a manufacturing process of the second example in the embodiment of the present invention. FIG. 4 is a cross-sectional view in which the cross section in the width direction of the metal strip obtained in each step of FIGS. 3A and 3B is enlarged in the thickness direction. In the second embodiment shown in FIGS. 3 and 4, parts common to the first embodiment are denoted by reference numerals obtained by adding 100 to the reference numerals in FIG. In the second embodiment, cold clad rolling using the rolling process shown in FIG. 3A is performed as the first rolling process. In the rolling process of FIG. 3A, three metal strips 103 (first coil strips) each having a metal strip 101 wound in a coil shape are introduced and three metal strips are inserted. The plate 101 is pulled out from the coiled metal strip 103, respectively. When the drawn metal strip 101 passes through the rolling roller 105 (cold rolling roll), it becomes a cold clad rolled metal strip 107 (metal strip 101 after cold clad rolling). The clad rolling by the rolling roller 105 is also performed cold (room temperature). Cold clad rolled metal strip 107 (metal strip 101 after cold rolling) is wound in a coil shape to form coiled metal strip 109 (second coiled metal strip).

  Next, cold rolling using the rolling process shown in FIG. 3B is performed as the second rolling process in the second embodiment. In the rolling process of FIG. 2, the coiled metal strip 109 manufactured in the rolling process (first rolling process) of FIG. 1 is introduced, and the cold clad rolled metal strip 107 is pulled out from the coiled metal strip 109. . The drawn cold clad rolled metal strip 107 passes through a rolling roller 111 (cold rolling roll), and becomes a cold rolled metal strip 113 (cold rolled metal strip 107 after cold rolling). . Rolling by the rolling roller 111 is also performed cold (room temperature). The cold-rolled metal strip 113 is wound in a coil shape to form a coil-shaped metal strip 115 (third coil-shaped metal strip).

  The coiled metal strip 115 constitutes an example of a rolled metal strip before annealing in the method for producing a metal strip material having ultrafine crystal grains according to the present invention. In addition, the coiled metal strip 115 becomes a metal strip material having ultrafine crystal grains of the present invention through an annealing process (not shown). As in the first embodiment, the annealing step may be performed before the cold clad rolled metal strip 113 is wound to form the coiled metal strip 115.

  Also in the second embodiment, the rolling reductions in the first and second rolling steps are determined so that the rolling equivalent strain of the coiled metal strip 115 is 3.8 or more. Specifically, as shown in FIG. 4, in the first rolling process shown in FIG. 3A, when the three metal strips 101 having a thickness of 1.50 mm are cold clad rolled, The rolling reduction r101 is determined so as to obtain a cold clad rolled metal strip 107 having a thickness of 1.00 mm. In this case, the reduction ratio r1 is 77.8%. In the second rolling step shown in FIG. 3B, when the cold-clad rolled metal strip 107 having a thickness of 1.00 mm is cold-rolled, a cold-rolled metal strip 113 having a thickness of 0.25 mm is obtained. The reduction ratio r102 is determined so that In this case, the rolling reduction is 87.5%. The metal strip 101 is also a metal strip having a width dimension of 150 mm.

When the rolling equivalent strain RS is calculated from the rolling reduction ratio ri from the above formula, the rolling equivalent strain RS101 in the first rolling step is 1.74, and the rolling equivalent strain RS102 in the second rolling step is 2.45. The total equivalent rolling strain RSt (RS101 + RS102), which is the sum of these equivalent rolling strains, is 4.19, and a condition for obtaining a metal strip material having ultrafine crystal grains with an average grain size of 2 μm or less (rolled metal before annealing) The condition corresponding to the rolling equivalent strain RS ≧ 3.8 of the strip is satisfied. Table 3 shows the relationship between the rolling reduction and rolling equivalent strain.

  Even in the second embodiment, the rolling equivalent strain can satisfy the condition of RS ≧ 3.8 only by performing cold rolling and cold clad rolling once, and it is handled in the state of a coiled metal strip. Can do.

  FIGS. 5A to 5C are diagrams illustrating a manufacturing process of the third example in the embodiment of the present invention. FIG. 6 is a cross-sectional view in which the cross section in the width direction of the metal strip obtained in each step of FIGS. 5A to 5C is enlarged in the thickness direction. In the third embodiment shown in FIGS. 5 and 6, parts common to the first embodiment are denoted by reference numerals obtained by adding the number of reference numerals 200 to the reference numerals of FIG. In the third example, cold rolling using the rolling process shown in FIG. 5A is performed as the first rolling process. In the rolling process of FIG. 3A, a coiled metal strip 203 (first coiled strip) in which a metal strip 201 is wound in a coil shape is introduced, and the metal strip 201 is turned into a coiled metal. Pull out from the strip 203 respectively. When the drawn metal strip 201 passes through a rolling roller 205 (cold rolling roll), it becomes a cold rolled metal strip 207 (cold rolled metal strip 201). Note that rolling by the rolling roller 205 is also performed cold (room temperature). The cold-rolled metal strip 207 (the metal strip 201 after cold rolling) is wound in a coil shape to become a coil-shaped metal strip 209 (second coil-shaped metal strip). The coiled metal strip 209 is made into three coiled metal strips in order to carry out a second rolling process described later.

  Next, as a second rolling process in the third embodiment, cold clad rolling using the rolling process shown in FIG. 5B is performed. In the rolling process of FIG. 5, the three coiled metal strips 209 manufactured in the rolling process (first rolling process) of FIG. 5A are introduced, and cold rolling is performed from the three coiled metal strips 209. Pull out the metal strip 207 respectively. When the three cold-rolled metal strips 207 drawn out pass through the rolling roller 211 (cold rolling roll machine), the cold-clad rolled metal strip 213 (cold-rolled metal strip 207 after cold-clad rolling) ) Rolling by the rolling roller 211 is also performed cold (room temperature). Cold-clad rolled metal strip 213 (three cold-clad rolled metal strips 207 after cold-clad rolling) is wound in a coil shape to form coil-shaped metal strip 215 (third coil-shaped metal strip). Board).

  In the third embodiment, the rolling process shown in FIG. 5C is further performed as a third rolling process. A coiled metal strip 215 (third coiled strip) in which the cold clad rolled metal strip 213 manufactured in FIG. 5B is wound in a coil shape is inserted and rotated in the direction of the arrow 216a. The cold-clad rolled metal strip 213 is pulled out from the coiled metal strip 215 by the supply roller 216. The drawn cold-clad rolled metal strip 213 continuously moves in the direction of arrow D203 and passes through a rolling roller 217 (cold rolling mill) that rotates in the direction of arrow 217a. Rolling by the rolling roller 217 is also performed cold (room temperature). The cold-clad rolled metal strip 213 that has passed through the rolling roller 217 continuously moves in the direction of arrow D203 and is wound into a coil by a winding machine (not shown) to form a coil-shaped metal strip 221 (fourth Coiled metal strip).

  The coiled metal strip 221 constitutes an example of a rolled metal strip before annealing in the method for producing a metal strip material having ultrafine crystal grains according to the present invention. Moreover, the coil-shaped metal strip 221 becomes a metal strip material having the ultrafine crystal grains of the present invention through an annealing process (not shown). As in the first embodiment, the annealing step may be performed before the cold clad rolled metal strip 219 is wound to form the coiled metal strip 221.

  In the third embodiment, the rolling reductions in the first, second, and third rolling steps are determined so that the rolling equivalent strain of the coiled metal strip 115 is 3.8 or more. Specifically, as shown in FIG. 6, in the first rolling step shown in FIG. 5 (A), when the metal strip 203 having a plate thickness of 2.00 mm is clad rolled, the plate thickness is 0.60 mm cold. The rolling reduction r201 is determined so as to be the rolled metal strip 207. In this case, the rolling reduction r201 is 70.0%. In the second rolling step shown in FIG. 5B, when cold-clad rolling is performed on three cold-rolled metal strips 207 having a thickness of 0.60 mm, cold-clad rolling with a thickness of 0.60 mm is performed. The rolling reduction r202 is determined so as to be the metal strip 213. In this case, the rolling reduction is 66.7%. Further, in the third rolling step shown in FIG. 5C, when the cold clad rolled metal strip 213 having a thickness of 0.60 mm is clad rolled, a cold rolled metal strip 219 having a thickness of 0.20 mm is obtained. The rolling reduction r203 is determined as follows. In this case, the rolling reduction r203 is 66.7%. The metal strip 201 is also a metal strip having a width dimension of 150 mm.

From the above formula, when the rolling equivalent strain RS is calculated from the reduction ratio ri, the rolling equivalent strain RS201 in the first rolling step is 1.39, and the rolling equivalent strain RS202 and RS203 in the second and third rolling steps are 1. .27. The total rolling equivalent strain RSt (RS201 + RS202 + RS203), which is the sum of these rolling equivalent strains, is 3.93, and the conditions for obtaining a metal strip material having ultrafine crystal grains with an average crystal grain size of 2 μm or less (rolled metal before annealing) The condition corresponding to the rolling equivalent strain RS ≧ 3.8 of the strip is satisfied. Table 4 shows the relationship between the rolling reduction and rolling equivalent strain.

  Even in the third embodiment, the rolling equivalent strain can satisfy the condition of RS ≧ 3.8 by performing cold rolling and cold clad rolling once, and it is handled in the state of a coiled metal strip. Can do.

  7A to 7D are diagrams for explaining a manufacturing process of the fourth example in the embodiment of the present invention. FIG. 8 is a cross-sectional view in which the cross section in the width direction of the metal strip obtained in each step of FIGS. 7A to 7D is enlarged in the thickness direction. In the fourth embodiment shown in FIGS. 7 and 8, the parts common to the third embodiment are described by adding the reference numerals obtained by adding 100 to the number of reference numerals in FIGS. 5 and 6. Omitted. In the third embodiment, the first to fourth rolling steps are performed. Among these, the 1st and 2nd rolling process of 3rd Example is common in the 1st and 2nd rolling process of 2nd Example. In the third example, after performing the first and second rolling steps, cold rolling is performed using the rolling step shown in FIG. 7C as the third rolling step. In the rolling process of FIG. 3 (A), the two coiled metal strips 315 manufactured in the rolling process (second rolling process) of FIG. The cold clad rolled metal strip 313 is pulled out. The two cold-clad rolled metal strips 313 drawn out become cold-clad rolled metal strips 319 when passing through a rolling roller 317 (cold rolling mill). Rolling by the rolling roller 317 is also performed cold (room temperature). The cold clad rolled metal strip 319 is wound in a coil shape to form a coiled metal strip 321 (third coiled metal strip).

  In the fourth embodiment, the rolling process of FIG. 7D is further performed as a fourth rolling process. Insert a coiled metal strip 321 (third coiled strip) in which the cold-clad rolled metal strip 319 manufactured in FIG. 7C is wound in a coil shape, and rotate in the direction of the arrow 322a. Then, the cold-clad rolled metal strip 319 is pulled out from the coiled metal strip 321 by the supply roller 322. The drawn cold clad rolled metal strip 319 continuously moves in the direction of arrow D304 and passes through a rolling roller 323 (cold rolling roll) that rotates in the direction of arrow 323a. Rolling by the rolling roller 323 is also performed cold (room temperature). The cold clad rolled metal strip 319 that has passed through the rolling roller 323 becomes a cold rolled metal strip 325. The cold-rolled metal strip 325 continuously moves in the direction of arrow D304 and is wound in a coil shape by a winding machine (not shown) to form a coil-shaped metal strip 327 (fourth coil-shaped metal strip). Become.

  Coiled metal strip 327 constitutes an example of a rolled metal strip before annealing in the method for producing a metal strip material having ultrafine crystal grains according to the present invention. In addition, the coiled metal strip 327 becomes a metal strip material having ultrafine crystal grains of the present invention through an annealing process (not shown). In the fourth embodiment, similarly to the first embodiment, the annealing step may be performed before the cold-clad rolled metal strip 325 is wound into the coiled metal strip 327.

  In the fourth embodiment, the rolling reduction ratios in the first, second, third, and fourth rolling processes are determined so that the rolling equivalent strain RS of the coiled metal strip 327 is 3.8 or more. . Specifically, as shown in FIG. 8, in the first rolling step shown in FIG. 7A, when the metal strip 301 having a plate thickness of 1.00 mm is cold-rolled, a cold plate having a thickness of 0.50 mm is obtained. The rolling reduction r301 is determined so as to be the intermediate rolled metal strip 307. The rolling reduction r301 in this case is 50.0%. In the second rolling step shown in FIG. 7B, when cold-clad rolling is performed on three cold-rolled metal strips 307 having a thickness of 0.50 mm, the cold-clad rolling having a thickness of 0.50 mm is performed. The rolling reduction r302 is determined so as to be the metal strip 313. In this case, the rolling reduction is 66.7%. Further, in the third rolling step shown in FIG. 5C, when cold-clad rolling is performed on two cold-clad rolled metal strips 313 having a thickness of 0.50 mm, the cold-clad rolling having a thickness of 0.40 mm is performed. The rolling reduction r303 is determined so that the metal strip 319 is obtained. The rolling reduction r303 in this case is 60.0%. Further, in the fourth rolling step shown in FIG. 7D, the cold-rolled metal strip 319 having a thickness of 0.40 mm is changed to a cold-rolled metal strip 325 having a thickness of 0.20 mm by cold rolling. The rolling reduction r304 is determined as follows. In this case, the rolling reduction r304 is 50.0%. The metal strip 301 is also a metal strip having a width dimension of 150 mm.

From the above formula, when the rolling equivalent strain RS is calculated from the reduction ratio ri, the rolling equivalent strain RS301 in the first rolling step is 0.80, the rolling equivalent strain RS302 in the second rolling step is 1.27, The rolling equivalent strain RS303 in the third rolling step is 1.06, and the rolling equivalent strain RS304 in the fourth rolling step is 0.80. The total rolling equivalent strain RSt (RS301 + RS302 + RS303 + RS304), which is the sum of these rolling equivalent strains, is 3.93, and the conditions for obtaining a metal strip material having ultrafine crystal grains with an average crystal grain size of 2 μm or less (rolled metal before annealing) The condition corresponding to the rolling equivalent strain RS ≧ 3.8 of the strip is satisfied. Table 5 shows the relationship between the rolling reduction and rolling equivalent strain.

  Also in the fourth embodiment, the rolling equivalent strain can satisfy the condition of RS ≧ 3.8 by performing cold rolling and cold clad rolling twice, and it is handled in the state of a coiled metal strip. Can do. In particular, in the fourth embodiment, since cold clad rolling is performed twice, even when the thickness of the metal strip material having ultrafine crystal grains is increased after annealing, a large equivalent strain to rolling can be given to the metal strip material. it can.

FIGS. 9A to 9C are diagrams illustrating a manufacturing process of the fifth example in the embodiment of the present invention. In the fifth embodiment shown in FIG. 9, parts common to the third embodiment are denoted by reference numerals obtained by adding 200 in addition to the reference numerals in FIG. 5, and description thereof is omitted. In the fifth embodiment, a heating step indicated by a heater 412 is provided between the supply roller 410 and the rolling roller 411 in the second rolling step shown in FIG. 9B. In the heating step indicated by the heater 412, the three cold rolled metal strips 407 are heated to a temperature below the recrystallization temperature. When such a heating step is provided, rolling by the rolling roller 411 is performed cold (temperature lower than the recrystallization temperature), and therefore cold rolling can be performed with less pressure than when cold (room temperature) rolling is performed. it can. Moreover, since rolling is performed cold (temperature lower than the recrystallization temperature), the second rolling step can be performed while maintaining the strain obtained in the first rolling step, so that the equivalent strain in rolling is reduced. It is possible to perform rolling. For the same reason, a heating process indicated by a heater 418 is provided between the supply roller 416 and the rolling roller 417 in the third rolling process shown in FIG. Table 6 shows the relationship between the rolling reduction and rolling equivalent strain in the fifth example.

  In the fifth embodiment, the same results as in the third embodiment can be obtained with less pressing than when cold (room temperature) rolling. In addition, in this Embodiment, what employ | adopted the above-mentioned heating process for 3rd Example is set as 5th Example, However, the above-mentioned heating process is used in 1st Example, 2nd Example, and 4th Example. Of course, it may be adopted.

  In the second to fifth embodiments, as in the first embodiment, 2-3 passes are rolled in the cold rolling step, and 1-2 passes are rolled in the cold clad rolling.

  When the rolled metal strip (SUS430) satisfying the condition of rolling equivalent strain RS ≧ 3.8 obtained by the above first to fifth embodiments was observed by SEM, the average crystal grain size was about 1 μm. It was confirmed that it was a metal strip material (SUS430) having ultrafine crystal grains.

  As described above, in the present embodiment, cold cladding rolling is performed twice in the fourth embodiment in order to give large rolling equivalent strain when the thickness of the metal strip material is increased. However, cold cladding rolling may be performed twice also in the first to third and fifth embodiments. When the cold clad rolling is performed twice in the first to third and fifth embodiments, a large rolling equivalent strain can be applied when the thickness of the metal strip material is increased. Further, in the present embodiment, in order to increase the ductility of the metal strip during rolling and facilitate the rolling operation, in the fifth example, some rolling processes (second and third rolling processes) are performed. The rolling object is heated to a temperature lower than the recrystallization temperature. However, the rolling process is not limited to all or a part of the rolling process of the first to fifth embodiments, and rolling may be performed by heating the rolling target to a temperature lower than the recrystallization temperature. When all or part of the rolling process is performed by heating the rolling target to a temperature lower than the recrystallization temperature, the ductility during rolling in all or part of the rolling process of the first to fifth embodiments is maintained while maintaining the strain. Can be bigger. Further, not only in the fifth embodiment, when cold clad rolling is performed by heating the rolling object to a temperature lower than the recrystallization temperature in the rolling process in which cold clad rolling is performed, the adhesion of the metal strip after clad rolling is performed. Can be high. Furthermore, in the first to fifth embodiments, in order to increase the ductility of the metal strip during rolling, instead of performing all or part of the rolling process by heating the rolling object to a temperature lower than the recrystallization temperature. The metal strip can be cooled after being heated to a temperature below the recrystallization temperature between all or part of the rolling steps.

In the first to fifth embodiments described above, when the rolling object is heated to a temperature lower than the recrystallization temperature, the rolling equivalent strain when cold clad rolling is performed twice, or all or part of the rolling process is performed. Tables 7 to 16 show the ductility during rolling and the adhesion of the rolled metal strip, and the ductility during rolling when cooled after being heated to a temperature lower than the recrystallization temperature between all or part of the rolling steps. . In Table 7, Example 1-1 shows the above-mentioned first example, Table 10 shows Example 2-1 in the above-mentioned second example, and Table 13 shows Example 3-1 and Example 3-6. Indicates the third and fifth embodiments, respectively. In Table 15, Example 4-1 indicates the fourth example.

  It should be noted that the number of metal strips stacked when cold clad rolling was performed twice was the same as the number of metal strips stacked in the fourth embodiment. The temperature of cold rolling and cold clad rolling in each rolling process was 500 ° C. (temperature lower than the recrystallization temperature of SUS430) when heated, and room temperature rt when not heated. Moreover, the temperature which heats the metal strip between each rolling process was 500 degreeC (temperature less than recrystallization temperature). The ductility of the metal strip during rolling and the adhesion of the rolled metal strip were evaluated as “good” when good, and “good” when very good.

  Tables 7 to 16 show the rolling equivalent strain in which fine crystal grains are generated by annealing even when the thickness of the metal strip material is increased by performing cold clad rolling twice in the first to fifth embodiments. It is shown that. Tables 7 to 16 show that the ductility during rolling can be increased by performing all or part of the rolling process in the first to fifth embodiments by heating the rolling object to a temperature lower than the recrystallization temperature. In addition, it is shown that the adhesion of the rolled metal strip is improved when the object to be rolled is heated to a temperature lower than the recrystallization temperature and cold clad rolling is performed. Further, Tables 7 to 16 show that in the first to fifth embodiments, instead of heating the rolling object to a temperature lower than the recrystallization temperature and carrying out all or part of the rolling process, Thus, by cooling the metal strip after heating it to a temperature lower than the recrystallization temperature, it is possible to increase the ductility during rolling, and it is possible to perform rolling with less pressure compared to rolling at room temperature.

  As mentioned above, although the embodiment of the present invention has been described focusing on the first to fifth examples, the present invention is of course not limited to these first to fifth examples.

(A) And (B) is a figure explaining the manufacturing process of 1st Example of this invention. It is an expanded sectional view of the metal strip obtained by each process of FIG. (A) And (B) is a figure explaining the manufacturing process of 2nd Example of this invention. It is an expanded sectional view of the metal strip obtained in each step of FIG. (A) thru | or (C) is a figure explaining the manufacturing process of 3rd Example of this invention. It is an expanded sectional view of the metal strip obtained by each process of FIG. (A) thru | or (D) is a figure explaining the manufacturing process of 4th Example of this invention. It is an expanded sectional view of the metal strip obtained in each step of FIG. (A) thru | or (C) is a figure explaining the manufacturing process of 5th Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal strip 3, 9, 15 Coiled metal strip 5,11 Rolling roller 7 Cold rolled metal strip 13 Cold clad rolled metal strip

Claims (13)

A method for producing a rolled metal strip having a rolling equivalent strain of 3.8 or more by rolling,
After cold rolling the metal strip drawn from the first coiled metal strip, in which the metal strip is wound in a coil shape, with a cold rolling mill, the metal strip after cold rolling is coiled A first rolling step for producing two or more second coiled metal strips wound around
Two or more metal strips drawn from the two or more second coiled metal strips are stacked, cold-rolled by a cold rolling mill, and then coiled after the cold-clad rolling. And a second rolling step for producing a third coiled metal strip by winding in a shape,
The cold rolling reduction in the first rolling step, the number of the two or more metal strips in the second rolling step, and the cold rolling reduction are expressed in terms of the rolling equivalent strain of the third coiled metal strip. A method for producing a rolled metal strip, characterized in that the third coiled metal strip is defined as 3.8 or more and is used as the rolled metal strip. A method for producing a rolled metal strip having a rolling equivalent strain of 3.8 or more by rolling,
After cold rolling the metal strip drawn from the first coiled metal strip, in which the metal strip is wound in a coil shape, with a cold rolling mill, the metal strip after cold rolling is coiled A first rolling step for producing two or more second coiled metal strips wound around
Two or more metal strips drawn from the two or more second coiled metal strips are stacked, cold-rolled by a cold rolling mill, and then coiled after the cold-clad rolling. A second rolling step for producing two or more third coiled metal strips wound in a shape;
Two or more metal strips drawn from the two or more third coiled metal strips are overlapped and cold-clad-rolled by a cold rolling roll machine, and then the cold-clad-rolled metal strip is coiled And a third rolling step for producing a fourth coiled metal strip by winding in a shape,
Cold rolling reduction in the first rolling step, number of the two or more metal strips in the second rolling step and cold rolling reduction, and the two or more metal strips in the third rolling step And the cold rolling reduction ratio of the fourth coiled metal strip so that the rolling equivalent strain of the fourth coiled metal strip is 3.8 or more, and the fourth coiled metal strip is the same as the rolled metal strip. A method for producing a rolled metal strip. A method for producing a rolled metal strip having a rolling equivalent strain of 3.8 or more by rolling,
After carrying out cold clad rolling with a cold rolling roll machine by laminating two or more metal strips drawn from two or more first coiled metal strips wound in a coil shape, A first rolling step of producing a second coiled metal strip by winding the metal strip after cold clad rolling into a coil;
After cold-rolling the clad-rolled metal strip drawn from the second coil-shaped metal strip with a cold rolling roll, the cold-rolled metal strip is wound into a coil shape to form a third A second rolling process for producing a coiled metal strip of
The number of the two or more metal strips and the cold reduction rate in the first rolling step and the cold reduction rate in the second rolling step are the same as the rolling equivalent strain of the third coiled metal strip. A method of manufacturing a rolled metal strip, wherein the third coiled metal strip is used as the rolled metal strip. A method for producing a rolled metal strip having a rolling equivalent strain of 3.8 or more by rolling,
After carrying out cold clad rolling with a cold rolling roll machine by laminating two or more metal strips drawn from two or more first coiled metal strips wound in a coil shape, A first rolling step of producing two or more second coiled metal strips by winding the metal strip after cold clad rolling into a coil;
Two or more metal strips drawn from the two or more second coiled metal strips are stacked, cold-rolled by a cold rolling mill, and then coiled after the cold-clad rolling. A second rolling step of producing a third coiled metal strip by winding in a shape;
After cold-rolling the clad-rolled metal strip drawn from the third coil-shaped metal strip with a cold rolling roll, the cold-rolled metal strip is wound into a coil shape to form a fourth And a third rolling step for producing the coiled metal strip of
The number and cold reduction rate of the two or more metal strips in the first rolling step, the number and cold reduction rate of the two or more metal strips in the second rolling step, and the third rolling step The cold reduction rate in the above is determined so that the rolling equivalent strain of the fourth coiled metal strip is 3.8 or more, and the fourth coiled metal strip is used as the rolled metal strip. A method for producing a rolled metal strip. A method for producing a rolled metal strip having a rolling equivalent strain of 3.8 or more by rolling,
After cold rolling the metal strip drawn from the first coiled metal strip, in which the metal strip is wound in a coil shape, with a cold rolling mill, the metal strip after cold rolling is coiled A first rolling step for producing two or more second coiled metal strips wound around
Two or more metal strips drawn from the two or more second coiled metal strips are stacked, cold-rolled by a cold rolling mill, and then coiled after the cold-clad rolling. A second rolling step of producing a third coiled metal strip by winding in a shape;
After cold-rolling the cold-clad rolled metal strip drawn from the third coiled metal strip with a cold rolling roll, the cold-rolled metal strip is wound into a coil. A third rolling step for producing a fourth coiled metal strip,
The cold rolling reduction in the first rolling step, the number of the two or more metal strips in the second rolling step and the cold rolling reduction, and the cold rolling reduction in the third rolling step are The coiled metal strip of No. 4 is set to have a rolling equivalent strain of 3.8 or more, and the fourth coiled metal strip is used as the rolled metal strip. Production method. A method for producing a rolled metal strip having a rolling equivalent strain of 3.8 or more by rolling,
After cold rolling the metal strip drawn from the first coiled metal strip, in which the metal strip is wound in a coil shape, with a cold rolling mill, the metal strip after cold rolling is coiled A first rolling step for producing two or more second coiled metal strips wound around
Two or more metal strips drawn from the two or more second coiled metal strips are stacked, cold-rolled by a cold rolling mill, and then coiled after the cold-clad rolling. A second rolling step for producing two or more third coiled metal strips wound in a shape;
Two or more metal strips drawn from the two or more third coiled metal strips are overlapped and cold-clad-rolled by a cold rolling roll machine, and then the cold-clad-rolled metal strip is coiled A third rolling step for producing a fourth coiled metal strip by winding in a shape;
After cold-rolling the cold-clad rolled metal strip drawn from the fourth coiled metal strip with a cold rolling roll, the cold-rolled metal strip is wound into a coil. A fourth rolling step for producing a fifth coiled metal strip,
Cold rolling reduction in the first rolling step, number of the two or more metal strips in the second rolling step and cold rolling reduction, the two or more metal strips in the third rolling step And the cold rolling reduction ratio in the fourth rolling step are determined so that the rolling equivalent strain of the fifth coiled metal strip is 3.8 or more, A method of manufacturing a rolled metal strip, wherein the coiled metal strip is the rolled metal strip.   In at least one of the first rolling step and the second rolling step, the cold clad rolling and / or the cold rolling is performed by heating a rolling target to a temperature lower than a recrystallization temperature. A method for producing a rolled metal strip according to claim 1 or 3.   In at least one of the first rolling step, the second rolling step, and the third rolling step, the cold clad rolling and / or the cold rolling is rolled to a temperature lower than the recrystallization temperature. The method for producing a rolled metal strip according to claim 2, 4 or 5, wherein the method is performed by heating.   In at least one of the first rolling step, the second rolling step, the third rolling step, and the fourth rolling step, the cold cladding rolling and / or the cold rolling is performed at a recrystallization temperature. The method for producing a rolled metal strip according to claim 6, wherein the rolling object is heated to a temperature lower than that.   The rolled metal according to claim 1 or 3, wherein a step of cooling after heating the metal strip to a temperature lower than a recrystallization temperature is performed between the first rolling step and the second rolling step. A manufacturing method of a strip.   Recrystallizing the metal strip between at least one step between the first rolling step and the second rolling step and between the second rolling step and the third rolling step. The method for producing a rolled metal strip according to claim 2, 4 or 5, wherein the step of cooling after heating to a temperature lower than the temperature is performed.   Between the first rolling step and the second rolling step, between the second rolling step and the third rolling step, and between the third rolling step and the fourth rolling step, The method for producing a rolled metal strip according to claim 6, wherein the step of cooling the metal strip after heating to a temperature lower than the recrystallization temperature is performed between at least one of the steps.   An ultrafine crystal having an average crystal grain size of 2 µm or less by heating and annealing the rolled metal strip produced by the production method according to any one of claims 1 to 12 to a temperature equal to or higher than a recrystallization temperature. A method for producing a metal strip material, comprising producing a metal strip material having grains.

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