Magnesium alloy sheet and method for manufacturing same

Abstract

A method for manufacturing a magnesium alloy sheet according to an embodiment of the present invention comprises the steps of casting a molten metal containing 2.7 to 5 wt % of Al, 0.75 to 1 wt % of Zn, 0.1 to 0.7 wt % of Ca and 1 wt % or less (Excluding 0 wt %) of Mn and consisting of the balance of Mg and inevitable impurities to produce a casted material (S 10 ), subjecting the casted material to homogenization heat treatment (S 20 ) and warm-rolling the casted material subjected to homogenization treatment (S 30 ).

1 . A magnesium alloy sheet containing 2.7 to 5 wt % of Al, 0.75 to 1 wt % of Zn, 0.1 to 1 wt % of Ca and 1 wt % or less (Excluding 0 wt %) of Mn and consisting of the balance of Mg and inevitable impurities,
 wherein the area fraction of the twin structure is 5% or less with respect to 100% of the area of the magnesium alloy sheet.   
     
     
         2 . A magnesium alloy sheet according to  claim 1 , containing 0.3 to 0.8 wt % of Ca. 
     
     
         3 . A magnesium alloy sheet according to  claim 1 ,
 wherein the magnesium alloy sheet comprises Al—Ca secondary phase particles comprising 20 to 25 wt % of Al, 5 to 10 wt % of Ca, 0.1 to 0.5 wt % of Mn, 0.5 to 1 wt % of Zn and the balance of Mg, and wherein the average particle size of the Al—Ca secondary phase particles is 0.01 to 4 μm.   
     
     
         4 . (canceled) 
     
     
         5 . A magnesium alloy sheet according to  claim 3 ,
 wherein the Al—Ca secondary phase particles comprises 5 to 15 per 100 μm 2  of the magnesium alloy sheet.   
     
     
         6 . A magnesium alloy sheet according to  claim 1 ,
 wherein the magnesium alloy sheet comprises grains and the average particle size of the grains is 5 to 30 μm.   
     
     
         7 . A magnesium alloy sheet according to  claim 1 , wherein the thickness of the magnesium alloy sheet is 0.4 to 2 mm. 
     
     
         8 . A method for manufacturing a magnesium alloy sheet comprising the steps of casting a molten metal containing 2.7 to 5 wt % of Al, 0.75 to 1 wt % of Zn, 0.1 to 1 wt % of Ca and 1 wt % or less (Excluding 0 wt %) of Mn and consisting of the balance of Mg and inevitable impurities to produce a casted material;
 subjecting the casted material to homogenization heat treatment; and   
       warm-rolling the casted material subjected to homogenization treatment. 
     
     
         9 . The method for manufacturing a magnesium alloy sheet of  claim 8 ,
 wherein the step of producing the casted material, the reduction pressure is 0.2 ton/mm 2  or more.   
     
     
         10 . The method for manufacturing a magnesium alloy sheet of  claim 8 , wherein subjecting the casted material to homogenization heat treatment is carried out for 1 to 28 hours at a temperature of 350 to 500° C. 
     
     
         11 . The method for manufacturing a magnesium alloy sheet of  claim 8 , wherein warm-rolling is at a temperature of 150 to 350° C., and wherein warm-rolling is performed a plurality of times and rolling is at a reduction ratio of 10% to 30% per time. 
     
     
         12 . (canceled) 
     
     
         13 . The method for manufacturing a magnesium alloy sheet of  claim 11 , further comprising the step of one or more times of intermediate annealing in the middle of a plurality of times of warm-rolling, and wherein the intermediate annealing is carried out for 1 to 10 hours at a temperature of 300 to 500° C. 
     
     
         14 . (canceled) 
     
     
         15 . The method for manufacturing a magnesium alloy sheet of  claim 8 , further comprising the step of subjecting to subsequent heat treatment after the step of warm-rolling. 
     
     
         16 . (canceled) 
     
     
         17 . A method for manufacturing a magnesium alloy sheet comprising the steps of preparing a master alloy comprising 2.7 wt % or more and 5 wt % or less of Al, 0.75 wt % or more and 1 wt % or less of Zn, 0.1 wt % or more and 1 wt % or less of Ca, more than 0 wt % and 1 wt % or less of Mn and the balance of inevitable impurities and magnesium, for a total of 100 wt %;
 casting the master alloy to produce a casted material;   
       subjecting the casted material to homogenization heat treatment; 
       warm-rolling the casted material subjected to homogenization heat treatment to produce a rolled material;
 subjecting the rolled material to subsequent heat treatment; and 
 
       carrying out a skin pass to the rolled material subjected to subsequent heat treatment to produce a magnesium alloy sheet. 
     
     
         18 . The method for manufacturing a magnesium alloy sheet of  claim 17 , wherein carrying a skin pass to the rolled material subjected to subsequent heat treatment to produce a magnesium alloy sheet, wherein the skin pass is carried out once, and
 wherein the skin pass is carried out at a temperature in the range of 250° C. to 350° C.   
     
     
         19 . (canceled) 
     
     
         20 . The method for manufacturing a magnesium alloy sheet of  claim 18 ,
 wherein by the step of carrying out a skin pass to the rolled material subjected to subsequent heat treatment to produce a magnesium alloy sheet,   the produced magnesium alloy sheet is rolled at a reduction ratio of 2 to 15% with respect to the thickness of the rolled material.   
     
     
         21 . (canceled) 
     
     
         22 . The method for manufacturing a magnesium alloy sheet of  claim 17 ,
 wherein the step of subjecting the casted material to homogenization heat treatment comprising   a first heat treatment step at a temperature in the range of 300° C. to 400° C.; and   a second heat treatment step at a temperature in the range of 400° C. to 500° C.   
     
     
         23 . The method for manufacturing a magnesium alloy sheet of  claim 22 ,
 wherein a first heat treatment step at a temperature in the range of 300° C. to 400° C. is carried out for 5 to 20 hours.   
     
     
         24 . The method for manufacturing a magnesium alloy sheet of  claim 23 ,
 wherein a second heat treatment step at a temperature in the range of 400° C. to 500° C.   
       is carried out for 5 to 20 hours. 
     
     
         25 . (canceled) 
     
     
         26 . The method for manufacturing a magnesium alloy sheet of  claim 24 ,
 wherein by the step of rolling the casted material subjected to homogenization heat treatment to produce a rolled material,   the casted material is rolled 1 to 15 times, and   wherein the step of rolling the casted material subjected to homogenization heat treatment to produce a rolled material   is carried out at 150° C. to 350° C.   
     
     
         27 . (canceled) 
     
     
         28 . The method for manufacturing a magnesium alloy sheet of  claim 17 ,
 wherein by the step of subjecting the rolled material to subsequent heat treatment, the rolled material is annealed at a temperature in the range of 300° C. to 550° C. is carried out for 1 to 15 hours.   
     
     
         29 - 33 . (canceled)