Effects of High Strain-rate Rolling on Microstructure and Properties of the Mg-4Zn Alloy

Effects of high strain-rate rolling on microstructure, mechanical properties and corrosion resistance of Mg-4Zn alloy were investigated by optical microscope (OM), scanning electron microscope (SEM), mass loss of immersion test and tensile testing. Results show that high strain-rate rolling after solution treatment produces homogenous dynamic recrystallization (DRX) with final grain size of 4 pm, leading to a significant mechanical property improvement. The tensile strength, yield strength and elongation are 286 MPa, 180 MPa and 27.4%, respectively. The solutionized and the as-rolled alloys have better corrosion resistance than the as-cast alloy, exhibiting a uniform filiform corrosion due to the lower fraction and the finer size of the second phase. The as-rolled alloy presents the best corrosion resistance with the average corrosion rate of 0.25 mg/(cm(2).d), about 1/5 of the as-cast alloy after soaking in Hank's solution for 15 d. It also shows the highest residual tensile strength (215 MPa), far above the as-cast and the solutionized alloys.