热处理对AlZn4SiPb合金组织和性能的影响

Effect of Heat Treatment on Microstructure and Properties of AlZn4SiPb Alloy

研究了AlZn4SiPb合金铸锭和2 mm板材热处理前后的组织、硬度和强度等性能。结果表明,铸锭中Pb元素存在偏析,后浇铸的铸锭中Pb含量相对更高,其以球状或条状分布于晶内和晶界处,均匀化热处理对其形貌影响不明显。均匀化热处理后,晶界处的析出相固溶进入基体中,AlZn4SiPb合金铸锭的硬度由78.9 HV升高至89.8 HV。冷轧态板材金相组织呈纤维状。随着热处理温度的升高,板材的硬度和强度先降低后升高。300℃热处理后,其硬度为45.5 HV,抗拉强度为179 MPa;500℃热处理后,板材硬度为HV90.9,抗拉强度为306 MPa,伸长率为28.5%。

In this paper, AlZn4 SiPb ingots were prepared by metal mould, the ingots were rolled to 2 mm after homogenization heat treatment.The microstructure, hardness and strength of ingots and 2 mm plates after heat treatment were tested.The results show that the segregation of Pb element is serious.The content of Pb in the ingot casted later is relatively higher.The Pb phase is distributed in grains and grain bounbaries in spherical or strip shape.Homogenization heat treatment has no obvious effect on the morphology of Pb phase.After heat treament, the hardness of alloy ingot is increased from 78.9 HV to 89.8 HV.The cold rolled sheet has fibrous structure.With the increase of heat treatment temperature, the hardness and strength of the sheet decreased first and then increased.After 300℃ heat treatment, the hardness of the sheet is 45.5 HV,the tensile strength is 179 MPa.After 500℃ heat treatment, the hardness of the sheet is 90.9 HV,the tensile strength is 306 MPa, the elongation is 28.5%.