Study on the Effect of Corrosion on Tensile Properties of GW63K Magnesium Alloy.

Tensile tests of GW63K (Mg-6Gd-3Y-Zr) magnesium alloy under different heat treatment conditions were performed after immersion of the test specimens in 3.5 wt.% NaCl aqueous solution for periods up to 72 h. Results indicate that pitting corrosion should be responsible for the severe degradation of the tensile properties including yield strength, tensile strength (corrosion residual strength), and elongation within the testing time. The extreme depth of the corrosion pit was statistically related to corrosion residual strength. The variation of corrosion residual strength exhibited an exponential decay trend from 0 to 72 h. Furthermore, heat treatment enhanced the corrosion resistance of the GW63K alloy by inhibiting both the initiation and growth of corrosion pits, thereby improving the corrosion residual strength of the alloy. The critical working strength of GW63K alloy was significantly improved (increased to 192 MPa from 132 MPa) via heat treatment.