离心铸造AZ61A镁合金管的显微组织和力学性能

Microstructure and Mechanical Properties of Centrifugal Casting AZ61A Magnesium Alloy Tube

利用离心铸造工艺制备大口径AZ61A镁合金薄壁管,研究了其显微组织及力学性能,与传统砂型凝固铸件进行了比较分析。结果表明,离心铸造镁合金管晶粒得到了显著的细化;平衡凝固条件下的L→α-Mg+β-Mg17Al12共晶转变在很大程度上被抑制,形成以过饱和初生相α-Mg为主相的凝固组织;合金元素的整体分布均衡;力学性能得到提高,断口上存在大量韧窝,具有准解理断裂特性,显示塑性得到了明显改善。

AZ61A magnesium alloy tube with large diameter and thin wall was fabricated by centrifugal casting technique.The microstructures and tensile properties of the tube were studied and it was compared with the conventional sand casting.The results show that the grains of the tube by centrifugal casting are significantly refined.The eutectic transformation L→ α-Mg＋β-Mg17Al12 are suppressed to a great extent under the balanced solidification condition.As a consequence,the alloying elements Al and Zn show much higher solid solubility and the microstructure of the tube dominantly consists of supersaturated primary α-Mg solid solution.The tensile properties of the centrifugal casting tube are remarkably increased.In addition,the fracture surfaces exhibit amounts of dimples,indicating quasi-cleavage ductile fracture characteristics,and the ductility is improved obviously.