Effects of high strain-rate rolling on microstructure and properties of the Mg-4Zn alloy

Abstract:

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. The results showed that high strain-rate rolling after solution treatment produced homogenous dynamic recrystallization (DRX) with final grain size of 4 μm leading to a significant mechanical property improvement. The tensile strength, yield strength and elongation were 285MPa, 180MPa and 27.4% respectively. The solutionized and the as-rolled alloys had better corrosion resistance than the as-cast, exhibiting a uniform filiform corrosion due to the lower fraction and the finer size of the second phase. The as-rolled alloy showed the best corrosion resistance with the average corrosion rate of 0.25 mg/cm2.d, about 1/5 of the as-cast alloy after soaking in Hank’s solution for 15 days. It also showed the highest residual tensile strength ( 215MPa), far above the as-cast and the solutionized alloys.