CAJ | 학술논문

为改善挤压铸造AZ81镁合金组织的不均匀性,对铸态试样进行均匀化热处理.采用金相显微镜、X射线衍射仪和扫描电镜对AZ81镁合金的组织与性能进行分析.结果表明:经400℃、8 h均匀化处理后,AZ81合金有效地消除了枝晶偏析,改善了材料的组织状态:合金硬度由HRE 73.72下降到HRE 57.68,屈服强度由130MPa增加到138MPa,抗拉强度由226MPa增加到258MPa,伸长率则由7.6%增加到13.6%;试样的室温拉伸断口均为准解理断裂,经均匀化处理后断裂方式由沿晶界的脆性断裂转变为韧性穿晶断裂.
위개선제압주조AZ81미합금조직적불균균성,대주태시양진행균균화열처리.채용금상현미경、X사선연사의화소묘전경대AZ81미합금적조직여성능진행분석.결과표명:경400℃、8 h균균화처리후,AZ81합금유효지소제료지정편석,개선료재료적조직상태:합금경도유HRE 73.72하강도HRE 57.68,굴복강도유130MPa증가도138MPa,항랍강도유226MPa증가도258MPa,신장솔칙유7.6%증가도13.6%;시양적실온랍신단구균위준해리단렬,경균균화처리후단렬방식유연정계적취성단렬전변위인성천정단렬.
To improve the organization heterogeneity of the squeeze casting magnesium alloy AZ81, the homogenization heat treatment to as-cast sample was carried out. The microstructure and performance of AZ81 magnesium alloy was analyzed by metallographic observation, X-ray diffraction and SEM. The results showed that after 400 ℃×8 h homogenization, the dendrite microsegregation of AZ81 alloy was effectively eliminated and the material status of the organization was improved. The hardness of alloy decreases from as-cast alloy HRE 73.72 to HRE 57.68, and a slight decrease in yield strength; tensile strength increases from 226 MPa of the as-cast alloy to 258 MPa, and the elongation increases from 7.6% to 13.6%. The room temperature tensile fracture is based on quasi-cleavage fracture. After homogenization heat treatment, the fracture mode translates from brittle fracture along the grain boundary into ductility transgranular fracture.