冷却速度对GW93镁合金铸态组织与性能的影响

Effect of Cooling Rate on As-Cast Microstructure and Properties of GW93 Mg-alloy

采用温度记录仪测定砂型、金属型、水冷金属型和液氮冷却金属型在凝固阶段的平均冷却速度,分析冷却速度对GW 93镁合金铸态组织、相组成和力学性能的影响,建立合金的α(Mg)晶粒尺寸、硬度、抗拉强度、伸长率与凝固冷却速度的关系。结果表明,随着冷却速度的提高,α(Mg)等轴晶明显细化,第二相尺寸明显减小,分布更均匀,非平衡相Mg3Gd增多,α(Mg)等轴晶尺寸与冷却速度的关系公式为D=46.139 v-1/3。随着冷却速度的提高,合金抗拉强度、断后伸长率和硬度也明显提高。

The effect of cooling rate on as-cast microstructure and mechanical properties of GW 93 alloys was studied by temperature recorder, OM, SEM-EDS and XRD , the alloy was solidified in sand, metal mold, water-cooled metal mold and nitrogen-cooled metal mold. The quantitative relationship between a （Mg） grain size, hardness, tensile strength, elongation and solidification cooling rates were established. The results show that a （Mg） grain are refined obviously with solidification cooling rate increasing from 0.8 ℃/s to 19.2 ℃/s, and the more uniform distribution of the second phase and the more quantity of non-equilibrium phase Mg3Gd are observed. The tensile strength, percentage elongation and hardness of the alloy are improved with solidification cooling rate increasing.