预时效对A357合金组织与力学性能的影响

Effect of pre-aging on microstructure and mechanical properties of A357 alloy

研究了低温预时效对含钪A357合金组织与力学性能的影响。结果表明,较理想的合金预时效工艺为120℃×4~6 h;120℃×4 h+175℃×5 h双级时效工艺使合金抗拉强度增至362 MPa,伸长率增至6%,分别较单级时效提高4.6%和7.1%。低温预时效能促进细密、弥散GP区的形成,有利于二次时效获得高密度、弥散分布的细小强化相Mg2Si,从而提高合金力学性能。

The effect of pre-aging on microstructure and mechanical properties of A357 alloy with Sc minor addition was investigated. The results reveal that the optimized pre-aging process parameters are 120 ℃ × 4-6 h,the tensile strength and elongation with the pre-aging at120 ℃ for 4 h followed 175 ℃ for 5 h reach 362 MPa and 6%,and the increasing ratios are 4. 6% and 7. 1% respectively compared with single aging treatment. The reason for such an obvious effect is that the density of uniformly dispersed Mg2 Si precipitates is greatly increased in the finally aged condition after pre-aging.