均匀化处理后液氨管道用3A21合金的组织及性能

Microstructure and properties of homogenized 3A21 alloy for liquid ammonia pipeline

采用光学显微镜(OM)、维氏硬度计、涡流电导仪、万能试验机等研究了3A21合金经不同温度(520~640℃)均匀化处理后的组织与性能。结果表明,最佳均匀化制度为620℃×8 h,经该工艺处理后合金未发现过烧组织,晶界细小,呈断续分布,晶内偏析情况得到缓解,有利于后续挤压加工。该工艺下合金均匀化态的硬度为40 HV5,电导率35.8%IACS。经最佳均匀化工艺(620℃×8 h)处理后挤压3A21合金型材的抗拉强度124 MPa,屈服强度77 MPa,伸长率48%,硬度37 HV5,电导率48.7%IACS。

Microstructure and properties of 3A21 alloy after different homogenization process were studied by using optical microscope,Vickers hardness tester,eddy current conductivity meter and universal testing machine.The results show that the best homogenization process is 620℃×8 h.After the treatment,no overburnt structure is found,the grain boundary is fine and distributed intermittently,and the segregation in the grain is alleviated,which is beneficial to the subsequent extrusion processing.Under the process,hardness in homogenization state is 40 HV5,conductivity is 35.8%IACS.After the optimized homogenization(620℃×8 h),the strength,elongation,hardness,and conductivity of extruded 3A21 alloy are respectively 124 MPa,77 MPa,48%,37 HV5 and 48.7%IACS.