Magnesium alloy plate and method for manufacturing same

1. A magnesium alloy plate comprising:

0.5 to 10 wt % of zinc (Zn), 1 to 15 wt % of aluminum (Al), and a balance of magnesium (Mg) and inevitable impurities,

wherein an average value of a texture intensity within a misorientation level of 30° or less is 3 or less based on an [0001] orientation of a (0002) plane,

wherein a deviation of c/a values of a hexagonal closed packed (HCP) crystal structure in the plate is 5% or less, and

wherein a limited dome height (LDH) at room temperature is 10 mm or more.

2. The magnesium alloy plate of claim 1 , wherein

a thickness is in a range of 0.4 to 2 mm.

3. The magnesium alloy plate of claim 2 , wherein

the magnesium alloy plate has a non-basal texture that is uniform in a thickness direction.

4. A manufacturing method of a magnesium alloy plate, the method comprising:

(a) solution-treating a magnesium casting material containing 0.5 to 10 wt % of zinc (Zn), 1 to 15 wt % of aluminum (Al), and a balance of magnesium (Mg) and inevitable impurities at 300 to 500° C. for 1 to 48 hours;

(b) pre-heating the solution-treated magnesium casting material at 300 to 500° C.; and

(c) rolling the pre-heated magnesium casting material together with a constraint member selected by following Relational Expression 1 to satisfy Relational Expressions 2 and 3; and

(d) solution-treating a thus-rolled magnesium alloy plate at 300 to 500° C. for 0.5 to 5 hours, wherein the rolling is constrained rolling that is performed at a cumulative reduction ratio of 70% or more:

1<|(σ mat −σ mg )|□σ mg −1 <20  Relational Expression 1

wherein σ mat and σ mg are the constraint member and a mean flow stress (MFS)(MPa) of the magnesium material, respectively,

0.4< N Reff ×( N Rtotal −1) −1   Relational Expression 2

wherein N Reff is a number of rolling passes to which a strain that is equal to or greater than an effective strain (ε eff ) is applied, and

N Rtotal is a total number of rolling passes, and

3<ε eff ×100<40  Relational Expression 3

wherein ε eff =|(T−T 0 )|×L ini −1 , and

T 0 (mm) and T (mm) are pre-deformation and post-deformation thicknesses of the magnesium plate, respectively, and L ini has the same meaning as T 0 .

5. The manufacturing method of claim 4 , wherein

the constraint member is designed to have a thickness exceeding 5% of the magnesium casting material.

6. The manufacturing method of claim 4 , wherein

an oil-coating treatment or a plating treatment is further performed after the rolling.