T6处理对AZ80-Ag镁合金环轧件拉伸及蠕变性能的影响

Effects of T6 Treatment on Tensile and Creep Properties of AZ80-Ag Magnesium Alloy by Hot Ring Rolling

应用热环轧技术制备出大尺寸的AZ80-Ag镁合金环轧件,利用扫描电子显微镜(SEM)、拉伸蠕变等试验方法,系统研究了T6热处理对环轧件拉伸和蠕变性能的影响。结果表明:热环轧后,环轧件内部大部分晶粒为动态再结晶晶粒,并在晶界上分布有少量析出相;经T6处理后,在晶界和晶粒内部析出β-Mg_(17)Al_(12)相,使合金屈服强度和抗拉强度明显提高;合金的蠕变速率经T6处理后降低,变形态和T6态的应力指数n分别为4.1和5.5,对应的蠕变机制为位错滑移和攀移。

Large size AZ80-Ag magnesium alloy ring rolled pieces were prepared by hot ring rolling technology.The effects of T6 heat treatment on tensile and creep properties of the ring rolled pieces were systematically studied by means of scanning electron microscope(SEM),tensile creep and other test methods.The results show that,after hot ring rolling,most of the inner grains are dynamic recrystallization grains,and a small amount of precipitated phase is distributed on the grain boundary.After T6 treatment,β-Mg_(17)Al_(12)phase is precipitated at grain boundary and inside the grain.The yield strength and tensile strength of the alloy are obviously improved by the strengthened phase in the Mg-Al alloy.The creep rate of the alloy decreases after T6 treatment.The stress indices n of the alloy in deformed state and T6 state are 4.1 and 5.5,respectively,and the corresponding creep mechanism is dislocation slip and climbing.