预退火时间对触变反挤压铜合金组织及性能的影响

Effect of Pre-annealing Time on Microstructure and Properties of Thixotropic Back-Extruded Copper Alloy

采用预退火-轧制-重熔应变诱导熔化激活法制备半固态浆料并进行反挤压成形制备铜合金轴套零件,研究预退火时间对铜合金显微组织与力学性能的影响。结果表明:预退火时间对铜合金轴套组织、力学性能的影响较大。预退火处理后ZCuSn10P1铜合金固相晶粒中Sn元素趋于均匀,700℃退火处理改善了ZCuSn10P1铜合金的元素偏析倾向。随着预退火时间增加,半固态铜合金轴套组织的平均晶粒尺寸逐渐增加,形状因子和液相率逐渐减小;轴套布氏硬度降低,抗拉强度和延伸率先增加后降低。综合性能较佳的预退火工艺为700℃退火2 h,此时ZCuSn10P1铜合金轴套组织均匀性好、元素分布均匀,轴套平均晶粒尺寸为73.06μm,平均形状因子为0.72,抗拉强度为382MPa,延伸率为5.5%,平均布氏(HBW)硬度为1244.6 MPa。

Semi-solid slurry was prepared by the pre-annealing-rolling-remelting strain-induced melting activation method and copper alloy bushing parts was prepared by back-extrusion.The effect of pre-annealing time on the microstructure,hardness,and mechanical properties of copper alloy bushings was studied.The results show that the pre-annealing time dramatically influences the structure,mechanical properties,and hardness of the semi-solid copper alloy bushing.After pre-annealing,the Sn content in ZCuSn10P1 copper alloy tends to be uniform.The elemental segregation tendency of ZCuSn10P1 copper alloy was improved by annealing at 700 ℃.With the increase of annealing time,the average grain size of sleeve structure increases,shape factor decreases,and liquid phase ra tio decreases.The Brinell hardness of the sleeve decreases,and the tensile strength and extension increase first and then decrease.The pre-annealing process with better comprehensive properties is 700 ℃ for 2 h.At this time,the microstructure uniformity and element distribution of the ZCuSn10P1 copper alloy sleeve are better,and the average grain size of the sleeve is 73.06 μm.The average shape factor is 0.72,tensile strength is 382 MPa,elongation is 5.5%,and average Brinell hardness(HBW) is 1244.6 MPa.