Highly molded magnesium alloy sheet and method for manufacturing same

Abstract

The present invention relates to a high-formed magnesium alloy sheet and a method of manufacturing the same. One embodiment of the present invention provides a magnesium alloy sheet comprising: 3.0 wt % or less (excluding 0 wt %) of Zn, 1.5 wt % or less (excluding 0 wt %) of Ca, 1.0 wt % or less (excluding 0 wt %) of Mn, balance of Mg and inevitable impurities, for a total of 100 wt %, wherein, the magnesium alloy sheet further comprises 0.3 wt % or less of Al, based on 100 wt % of the entire magnesium alloy sheet, and the magnesium alloy sheet satisfies the following formulas (1) and (2): [Zn]/[Ca]≤4.0  formula (1) [Zn]+[Ca]>[Mn]  formula (2) [Zn], [Ca], and [Mn] refer to weight percent of each component.

1 . A magnesium alloy sheet comprising:
 3.0 wt % or less (excluding 0 wt %) of Zn, 1.5 wt % or less (excluding 0 wt %) of Ca, 1.0 wt % or less (excluding 0 wt %) of Mn, balance of Mg and inevitable impurities, for a total of 100 wt %,   wherein, the magnesium alloy sheet further comprises 0.3 wt % or less of Al, based on 100 wt % of the entire magnesium alloy sheet, and   the magnesium alloy sheet satisfies the following formulas (1) and (2):
   [Zn]/[Ca]≤4.0  formula (1)
 
   [Zn]+[Ca]>[Mn]  formula (2)
 
   [Zn], [Ca], and [Mn] refer to weight percent of each component.   
     
     
         2 . The magnesium alloy sheet of  claim 1 ,
 wherein, a maximum texture intensity based on the {0001} plane of the magnesium alloy sheet is 1 to 4.   
     
     
         3 . The magnesium alloy sheet of  claim 1 ,
 wherein, the magnesium alloy sheet has 7 to 10 mm of Limit Dome Height (LDH).   
     
     
         4 . The magnesium alloy sheet of  claim 1 ,
 wherein, the magnesium alloy sheet has 170 MPa or more of yield strength.   
     
     
         5 . The magnesium alloy sheet of  claim 1 ,
 wherein, the magnesium alloy sheet has 240 MPa or more of tensile strength.   
     
     
         6 . The magnesium alloy sheet of  claim 1 ,
 wherein, the magnesium alloy sheet has 20% or more of elongation percentage.   
     
     
         7 . The magnesium alloy sheet of  claim 1 ,
 wherein, the magnesium alloy sheet comprises crystal grain having an average particle size of 1 to 20 μm.   
     
     
         8 . The magnesium alloy sheet of  claim 1 ,
 wherein, the magnesium alloy sheet comprises a Mg—Ca based secondary phase, and   the average particle size of the secondary phase is 30 μm or less.   
     
     
         9 . The magnesium alloy sheet of  claim 1 ,
 wherein the magnesium alloy sheet comprises 1 to 20 secondary phases per 100 μm 2  of the magnesium alloy sheet area.   
     
     
         10 . A method of manufacturing a magnesium alloy sheet comprising:
 preparing a cast material by casting a molten alloy comprising 3.0 wt % or less (excluding 0 wt %) of Zn, 1.5 wt % or less (excluding 0 wt %) of Ca, 1.0 wt % or less (excluding 0 wt %) of Mn, balance of Mg and inevitable impurities, for a total of 100 wt %;   subjecting the cast material to homogenizing heat treatment;   preparing a rolled material by subjecting the homogenizing heat treated cast material to hot rolling; and   final annealing the rolled material;   wherein, the molten alloy further comprises 0.3 wt % or less of Al, based on 100 wt % of the entire molten alloy, and   the magnesium alloy sheet satisfies the following formulas (1) and (2):
   [Zn]/[Ca]≤4.0  formula (1)
 
   [Zn]+[Ca]>[Mn]  formula (2)
 
   [Zn], [Ca], and [Mn] refer to weight percent of each component.   
     
     
         11 . The method of  claim 10 ,
 wherein, in the step of final annealing the rolled material,   a temperature range is from 200 to 500° C.   
     
     
         12 . The method of  claim 11 ,
 wherein, a step of the final annealing the rolled material is conducted for less than 5 hours (excluding 0 hours).   
     
     
         13 . The method of  claim 10 ,
 wherein, in a step of the subjecting the cast material to homogenizing heat treatment;   a temperature range is from 300 to 500° C.   
     
     
         14 . The method of  claim 13 ,
 wherein, a step of the subjecting the cast material to homogenizing heat treatment is conducted for 5 hours to 30 hours.   
     
     
         15 . The method of  claim 10 ,
 wherein, in a step of preparing a rolled material by subjecting the homogenizing heat treated cast material to hot rolling,   a temperature range is from 150 to 400° C.   
     
     
         16 . The method of  claim 15 ,
 wherein, the step of preparing a rolled material by subjecting the homogenizing heat treated cast material to hot rolling,   the cast material is rolled once or twice at a reduction ratio of not more than 40% (excluding 0%) per rolling.   
     
     
         17 . The method of  claim 16 ,
 wherein, the step of preparing a rolled material by subjecting the homogenizing heat treated cast material to hot rolling,   the cast material is hot-rolled twice or more, and   an intermediate annealing is performed at least once between hot rolling.   
     
     
         18 . The method of  claim 17 ,
 the intermediate annealing is performed at a temperature range of 300 to 500° C.   
     
     
         19 . The method of  claim 18 ,
 the intermediate annealing is performed for 5 hours or less (excluding 0 hours).