累积叠轧道次对AZ31镁合金板微观组织和力学性能的影响

Effect of ARB Passes on Microstructure and Mechanical Properties of AZ31 Magnesium Alloy Plate

开展400℃轧制温度下的累积叠轧试验,并利用光学显微镜、拉伸试验机、显微硬度计、X射线衍射仪、扫描电镜对不同累积叠轧道次板材的微观组织和力学性能进行表征,研究累积叠轧道次对AZ31镁合金板材晶粒尺寸、基面织构、力学性能的影响。结果表明:累积叠轧工艺的晶粒细化主要发生在前3道次,随后的循环道次中晶粒不再明显细化,甚至略微长大。第3道次的综合力学性能最佳。剪切带的存在虽缓解了应力集中,提高了塑性,弱化了基面织构,但该处也易形成裂纹,加速板材的断裂,使伸长率急剧下降。基面织构强度随着轧制道次的增加呈先减弱后增强的趋势。

The accumulative roll-bonding(ARB)experiment at 400℃rolling temperature was carried out.The microstructure and mechanical properties of AZ31 magnesium alloy plate with different rolling passes were characterized by optical microscope,tensile testing machine,microhardness tester,X-ray diffractometer and scanning electron microscope.The effects of ARB passes on the grain size,basal texture and mechanical properties of AZ31 magnesium alloy plate were studied.The results show that the grain refinement of ARB process mainly occurs in the first three passes,and the grain is no longer obviously refined,even slightly grows in the subsequent cycle passes.The comprehensive mechanical properties are the best in the third pass.Although the existence of shear band alleviates the stress concentration,improves the plasticity and weakens the basal texture,it is also easy to form cracks,accelerates the fracture of the plate and sharply reduces the elongation.The base texture strength decreases first and then increases with the increase of rolling passes.