锻造热处理工艺对Al-7Si-1.6Cu合金组织和力学性能的影响

通过力学性能测试以及OM、SEM和TEM的组织观察,研究了锻造热处理工艺对Al-7Si-1.6Cu合金组织与力学性能的影响。结果表明,合金经过均匀化(500℃,8h)、锻造(锻造温度380~450℃,应变速率60~90s-1,道次压缩比10%~20%)、热处理(固溶480℃,2h,70℃,水冷;时效180℃,6h)之后,较铸态相比硬度提高18%、抗拉强度提高了52%、延伸率提高了54.5%。多向锻造过程中共晶Si相发生碎断与球化,时效过程中析出的纳米级第二相对合金起强化作用。开创性地从位错密度方向解释锻造过程强度提高的原因,通过Zener-Hollomon参数来说明锻造过程中流变应力与变形速率和变形温度之间的关系。

Effects of Forging and Heat Treatment Processing on Structure and Mechanical Properties of Al-7Si-1.6Cu Alloy

Effects of forging and heat treatment on microstructure and mechanical properties of Al-7Si-1.6Cu alloy were investigated by means of mechanics performance test,OM,SEM and TEM observations.Results showed that by homogenization processing(500 ℃,8 h),forging(forging temperature from 380 ℃ to 450 ℃,strain rate 60-90 s-1,pass compression ratio 10％-20％)and heat treatment(solid solution at 480 ℃ for 2 h,70 ℃ water-quenching,aging at 180 ℃ for 6 h),the hardness,tensile strength and elongation of the alloy increased by 18 ％,52 ％ and 54.5 ％ compared with the as-cast.Multidirectional forging process accelerated the breaking and spheroidizing of the eutectic Si particles.The precipitation of nanoscale second phase in the aging process had strengthening effect to the alloy.From the point of the dislocation density,the article explained the reasons for strength improvement by forging process.Zener-Hollomon parameters were adopted to illustrate the relationship of the forging process flow stress between deformation temperature and deformation rate.