高应变速率轧制对Mg-4Zn合金组织及性能的影响

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

摘要:

采用光学显微镜、扫描电镜、浸泡质量损失和拉伸测试等手段研究了高应变速率轧制对Mg-4Zn合金微观组织、力学性能及耐腐蚀性能的影响。结果表明：固溶处理后进行高应变速率轧制，Mg-4Zn合金发生了均匀的动态再结晶，平均晶粒尺寸为4 μm，力学性能明显改善，抗拉强度、屈服强度和伸长率分别为285 MPa、180 MPa和27.4%。固溶态、轧制态合金由于第二相含量及尺寸明显小于铸态，腐蚀方式为较均匀的丝状腐蚀，耐蚀性大大提高。Hank’s溶液中浸泡15 d实验表明，轧制态耐蚀性最佳，平均腐蚀速率为0.25 mg/cm2?d，约为铸态的1/5；其剩余抗拉强度最高为215 MPa，远高于铸态和固溶态。

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.