Rolled magnesium alloy material, magnesium alloy structural member, and method for producing rolled magnesium alloy material

Abstract

Provided are a rolled Mg alloy material which has a wide width and whose mechanical properties are uniform in a width direction, a Mg alloy structural member produced by plastically working the rolled Mg alloy material, and a method for producing the rolled Mg alloy material. The method for producing a rolled Mg alloy material includes rolling a Mg alloy material with a reduction roll. The Mg alloy material has a width of 1,000 mm or more, and the reduction roll has three or more regions in the width direction. The temperature is controlled in each of the regions so that a difference between a maximum temperature and a minimum temperature is 10° C. or less in the width direction of a surface of the reduction roll. The variation in the rolled state in the width direction can be reduced by reducing a difference in temperature over the width direction of the reduction roll. As a result, it is possible to produce a rolled Mg alloy material whose mechanical properties are substantially uniform in the width direction.

What is claimed is: 
     
         1 .- 13 . (canceled) 
     
     
         14 . A rolled magnesium alloy material produced by rolling a magnesium alloy material with a reduction roll,
 wherein the rolled magnesium alloy material has a width of 1,000 mm or more, and   in a width direction of the rolled magnesium alloy material,   a ratio O E /O C  of a basal plane peak ratio of an edge portion to a basal plane peak ratio of a central portion satisfies 0.89≦O E /O C ≦1.15,   where the basal plane peak ratio O C  of the central portion and the basal plane peak ratio O E  of the edge portion are respectively represented by formulae below:
   basal plane peak ratio O C : I C (002)/{I C (100)+I C (002)+I C (101)+I C (102)+I C (110)+I C (103)} 
   basal plane peak ratio O E : I E (002)/{I E (100)+I E (002)+I E (101)+I E (102)+I E (110)+I E (103)} 
 where I C (002), I C (100), I C (101), I C (102), I C (1110), and I C (103) respectively represent X-ray diffraction peak intensities of a (002) plane, a (100) plane, a (101) plane, a (102) plane, a (110) plane, and a (103) plane in the central portion, and 
 I E (002), I E (100), I E (101), I E (102), I E (110), and I E (103) respectively represent X-ray diffraction peak intensities of the (002) plane, the (100) plane, the (101) plane, the (102) plane, the (110) plane, and the (103) plane in the edge portion. 
   
     
     
         15 . The rolled magnesium alloy material according to  claim 14 ,
 wherein an average grain size ratio D E /D C  of the edge portion to the central portion satisfies 0.7≦D E /D C ≦1.5,   where D C  denotes an average grain size of the central portion of a cross section orthogonal to a rolling direction and D E  denotes an average grain size of the edge portion of a cross section orthogonal to a rolling direction.   
     
     
         16 . The rolled magnesium alloy material according to  claim 14 ,
 wherein an elongation ratio E E /E C  of the edge portion to the central portion satisfies 2/3≦E E /E C ≦3/2,   where E C  denotes an elongation of the central portion in a tensile test in a rolling direction and E E  denotes an elongation of the edge portion in a tensile test in a rolling direction.   
     
     
         17 . The rolled magnesium alloy material according to  claim 14 ,
 wherein a tensile strength ratio Ts E /Ts C  of the edge portion to the central portion satisfies 0.9≦Ts E /Ts C ≦1.1,   where Ts C  denotes a tensile strength of the central portion in a tensile test in a rolling direction and Ts E  denotes a tensile strength of the edge portion in a tensile test in a rolling direction.   
     
     
         18 . The rolled magnesium alloy material according to  claim 14 ,
 wherein a 0.2% proof stress ratio Ps E /Ps C  of the edge portion to the central portion satisfies 0.9≦Ps E /Ps C ≦1.1,   where Ps C  denotes a 0.2% proof stress of the central portion in a tensile test in a rolling direction and Ps E  denotes a 0.2% proof stress of the edge portion in a tensile test in a rolling direction.   
     
     
         19 . The rolled magnesium alloy material according to  claim 14 ,
 wherein the magnesium alloy material contains aluminum in an amount of 5% by mass or more and 12% by mass or less.   
     
     
         20 . A magnesium alloy structural member produced by plastically working the rolled magnesium alloy material according to  claim 14 . 
     
     
         21 . A method for producing a rolled magnesium alloy material comprising rolling a magnesium alloy material with a reduction roll to produce a rolled magnesium alloy material,
 wherein the magnesium alloy material has a width of 1,000 mm or more,   the reduction roll has three or more regions in a width direction, and   the temperature is controlled in each of the regions so that a difference between a maximum temperature and a minimum temperature is 10° C. or less in the width direction of a surface of the reduction roll.   
     
     
         22 . The method for producing a rolled magnesium alloy material according to  claim 21 , wherein the temperature is controlled by introducing, into the reduction roll, heat transfer oil whose temperature has been adjusted. 
     
     
         23 . The method for producing a rolled magnesium alloy material according to  claim 21 , wherein the temperature is controlled by allowing a heating fluid whose temperature has been adjusted to adhere to the surface of the reduction roll. 
     
     
         24 . The method for producing a rolled magnesium alloy material according to  claim 21 , wherein the temperature is controlled so that, on the surface of the reduction roll, a difference in temperature between two points 100 mm away from each other in the width direction is 6° C. or less. 
     
     
         25 . The method for producing a rolled magnesium alloy material according to  claim 21 , wherein preheating is performed so that, on a surface of the magnesium alloy material immediately before the magnesium alloy material passes through the reduction roll, a difference between a maximum temperature and a minimum temperature in the width direction is 8° C. or less. 
     
     
         26 . The method for producing a rolled magnesium alloy material according to  claim 21 ,
 wherein preheating is performed so that, on a surface of the magnesium alloy material immediately before the magnesium alloy material passes through the reduction roll, a difference in temperature between two points 100 mm away from each other in the width direction is 6° C. or less, and   the temperature is controlled so that, on the surface of the rolled magnesium alloy material immediately after the magnesium alloy material passes through the reduction roll, a difference in temperature between two points 100 mm away from each other in the width direction is 6° C. or less.