静液挤压及退火处理对AZ80镁合金组织及力学性能的影响

Effects of Hydrostatic Extrusion and Annealing Heat Treatment on Microstructure and Mechanical Properties of AZ80 Magnesium Alloy

通过不同状态AZ80镁合金的金相组织观察、力学性能试验和断口SEM分析,研究了静液挤压及退火热处理对AZ80镁合金组织及力学性能的影响。结果表明:经静液挤压后,镁合金组织发生动态再结晶,生成细小再结晶晶粒,再结晶晶粒尺寸10μm左右,镁合金抗拉及屈服强度明显提高,分别达到325 MPa和241 MPa。退火热处理后,在高温热能的驱动下镁合金组织发生了静态再结晶,同时位错能得到释放,使镁合金伸长率大幅度提高,达到8.1%。均匀化态的镁合金断裂属于韧性和脆性混合型断裂;挤压态镁合金断裂是脆性解理断裂;退火热处理态镁合金表现为沿晶脆性断裂,但与挤压态相比,断口有向韧性断裂过渡的倾向。

The effects of hydrostatic extrusion and annealing heat treatment on the microstructure and mechanical properties of AZ80 magnesium alloy were studied by metallographic observation, mechanical properties test and fracture SEM analysis. The results show that, after hydrostatic extrusion, the microstructure of magnesium alloy is recrystallized dynamically and the fine recrystallized grains are formed. The size of recrystallization grain is about 10 μm. The tensile strength and yield strength of magnesium alloy increase obviously, reaching 325 MPa and 241 MPa, respectively. After annealing heat treatment,static recrystallization occurs in the microstructure of magnesium alloy driven by high temperature heat energy. At the same time, dislocation energy is released, and the elongation of magnesium alloy increases to 8.1%. The fracture of homogeneous magnesium alloy belongs to ductile and brittle mixed fracture, and the extruded magnesium alloy fracture is brittle cleavage fracture. The annealed magnesium alloy exhibits brittle fracture along the grain, but the fracture surface tends to transition to ductile fracture in comparison with the extruded alloy.