离心铸造对AZ91镁合金组织及力学性能的影响

为了研究卧式离心铸造工艺对AZ91镁合金力学性能及显微组织的影响,采用卧式离心铸造方法制备外径为400 mm、厚度为20 mm且长度为1 000 mm的AZ91镁合金管材,并对离心铸造态与自然凝固态AZ91镁合金管材的微观组织及力学性能分别进行了观察与测试.结果表明,离心铸造态AZ91镁合金管材的抗拉强度和伸长率分别为158 MPa和3.4%,与自然凝固态管材相比分别提高了20%和89%.离心铸造态镁合金管材的微观组织得到明显细化.与自然凝固态AZ91镁合金管材相比,离心铸造态AZ91镁合金管材在凝固过程中的共晶转变在很大程度上受到抑制,并形成了以α-Mg为主相的组织.卧式离心铸造方法提高了AZ91镁合金的综合力学性能,并使合金的组织得到细化.

Effect of centrifugal casting on microstructure and mechanical properties of AZ91 magnesium alloy

In order to study the effect of horizontal centrifugal casting on the mechanical properties and microstructure of AZ91 magnesium alloy, the AZ91 magnesium alloy tube with outer diameter of 400 mm, thickness of 20 mm and length of 1 000 mm was prepared with the horizontal centrifugal casting method. The microstructure and mechanical properties of AZ91 magnesium alloy tubes at both centrifugal casting and natural solidification states were tested and observed. The results show that the tensile strength and elongation of AZ91 magnesium alloy tube at centrifugal casting state are 158 MPa and 3.4% respectively, which respectively increase by 20% and 89% compared with those of tube at natural coagulation state. The microstructure of AZ91 magnesium alloy tube at centrifugal casting state gets obviously refined. Compared with the AZ91 magnesium alloy tube at the natural solidification state, the eutectic transition in the solidification process of AZ91 magnesium alloy tube at the centrifugal casting state is inhibited to a large extent, and the microstructure taking α-Mg as the main phase is formed. The horizontal centrifugal casting method improves the mechanical properties of AZ91 magnesium alloy, and refines the microstructure of the alloy.