Magnesium alloy sheet and manufacturing method therefor

Abstract

The present invention relates to a magnesium alloy sheet comprising: 0.1 to 1.5 wt % of Zn, 0.08 to 0.7 wt % of Gd, a remainder of Mg, and other inevitable impurities with respect to an entire 100 wt % of the magnesium alloy sheet, and the magnesium alloy sheet may satisfy Relational Expression 1 below. [Zn]/[Gd]≥3.0  [Relational Expression 1] The [Zn] and [Gd] may indicate wt % of each component.

What is claimed is: 
     
         1 . A magnesium alloy sheet comprising:
 0.1 to 1.5 wt % of Zn, 0.08 to 0.7 wt % of Gd, a remainder of Mg, and other inevitable impurities with respect to an entire 100 wt % of the magnesium alloy sheet,   wherein the magnesium alloy sheet satisfies Relational Expression 1:
   [Zn]/[Gd]≥3.0  [Relational Expression 1]
 
   wherein the [Zn] and [Gd] indicate wt % of each component.   
     
     
         2 . The magnesium alloy sheet of  claim 1 , wherein
 the magnesium alloy sheet satisfies Relational Expression 2:
   15.0≥[Zn]/[Gd]≥3.0  [Relational Expression 2]
 
   wherein the [Zn] and [Gd] indicate wt % of each component.   
     
     
         3 . The magnesium alloy sheet of  claim 2 , wherein
 the magnesium alloy sheet satisfies Relational Expression 3:
   13.0≥[Zn]/[Gd]≥3.0  [Relational Expression 3]
 
   wherein the [Zn] and [Gd] indicate wt % of each component.   
     
     
         4 . The magnesium alloy sheet of  claim 3 , further comprising
 0.3 wt % or less of Mn (excluding 0 wt %) with respect to the total of 100 wt % of the magnesium alloy sheet.   
     
     
         5 . The magnesium alloy sheet of  claim 4 , wherein
 the magnesium alloy sheet comprises a secondary phase, and   the number of secondary phases per an area of 40000 μm 2  of the magnesium alloy plate is 1 to 20.   
     
     
         6 . The magnesium alloy sheet of  claim 5 , wherein
 the magnesium alloy sheet comprises a secondary phase, and   the average particle diameter of the secondary phase is 0.1 to 3 μm.   
     
     
         7 . The magnesium alloy sheet of  claim 6 , wherein
 an average crystal grain size of the magnesium alloy sheet is 5 to 30 μm.   
     
     
         8 . The magnesium alloy sheet of  claim 7 , wherein
 the limited dome height (LDH) of the magnesium alloy sheet is 10.5 mm or more.   
     
     
         9 . The magnesium alloy sheet of  claim 8 , wherein
 an edge crack of the magnesium alloy sheet is 5 mm or less.   
     
     
         10 . The magnesium alloy sheet of  claim 9 , wherein
 the magnesium alloy plate has a maximum texture intensity of 4.5 or less with respect to the (0001) plane.   
     
     
         11 . A method for manufacturing a magnesium alloy sheet, comprising:
 preparing a casting material by casting an alloy melt solution comprising 0.1 to 1.5 wt % of Zn, 0.08 to 0.7 wt % of Gd, a remainder of Mg, and other inevitable impurities for the entire 100 wt %;   homogenizing and heat-treating the casting material;   preparing a rolled material by rolling the homogenized and heat-treated casting material; and   finally annealing the rolled material,   wherein the alloy melt solution satisfies Relational Expression 4:
   [Zn]/[Gd]≥3.0  [Relational Expression 4]
 
   wherein the [Zn] and [Gd] indicate wt % of each component.   
     
     
         12 . The method of  claim 11 , wherein
 the alloy melt solution satisfies Relational Expression 5:
   15.0≥[Zn]/[Gd]≥3.0  [Relational Expression 5]
 
   wherein the [Zn] and [Gd] indicate wt % of each component.   
     
     
         13 . The method of  claim 12 , wherein
 the alloy melt solution satisfies Relational Expression 6:
   13.0≥[Zn]/[Gd]≥3.0  [Relational Expression 6]
 
   wherein the [Zn] and [Gd] indicate wt % of each component.   
     
     
         14 . The method of  claim 11 , wherein
 the alloy melt solution further comprises 0.3 wt % or less of Mn (excluding 0 wt %) with respect to the total of 100 wt % of the magnesium alloy sheet.   
     
     
         15 . The method of  claim 11 , wherein
 the homogenizing and heat-treating of a casting material is performed at a temperature of 300 to 500° C.   
     
     
         16 . The method of  claim 15 , wherein
 the homogenizing and heat-treating of a casting material is performed for 5 hour or more.   
     
     
         17 . The method of  claim 11 , wherein
 the preparing of a rolled material comprises performing rolling at a temperature of 150 to 350° C.   
     
     
         18 . The method of  claim 17 , wherein
 the preparing of a rolled material comprises performing a rolling with a reduction ratio that is greater than 0 and equal to or less than 30% for each rolling.