时效热处理消减2A02铝合金淬火残余应力的微观机理

Micro-mechanisms of quenching residual stress reduction for 2A02 aluminum alloy under aging treatment

将2A02铝合金进行500℃/2 h固溶淬火处理后的不同温度及时间的时效热处理,结合压痕硬度法及透射电镜精细结构分析,研究2A02铝合金时效前后的组织和相演化及与残余应力变化的关联性。结果表明,170℃时效处理时,随着时效时间的延长,2A02铝合金表面淬火残余应力的消减效果越好,当时效时间达到16 h时,残余应力消减程度最为显著,可达原淬火残余应力的42.9%,而190℃时效热处理后淬火残余应力消减不明显。进一步的组织分析表明,170℃时效时,随着时效时间的延长,针状S'(Al2Cu Mg)相的数量增多且不断长大粗化,S'相产生的共格应力场与淬火残余应力叠加,达到消减淬火残余应力的目的;而190℃时效热处理后S'相的数量极少,使得样品表面淬火残余应力消减并不明显。

Different aging processes were adopted for the as-solution treated 2A02 aluminum alloy; the microstructure evolution and residual stresses distribution for this alloy before and after aging treatment were investigated by TEM and micro-indentation method. The results indicate that the effect of residual stress reduction through aging treatment at 170 ℃ is far better than that at 190 ℃. When the aging at 170 ℃ for 16 h,the residual stress of the alloy can reduce the most and the reduction value is almost 42. 9% of the primary residual stress. Further microstructure analysis show that a portion of S'( Al2 Cu Mg) phase precipitates under 170 ℃ aging treatment,and the quantity of S' phase increases with increasing of the aging time. These S' phases produce the coherency stress field which interacts with the quenching residual stress field,resulting into the value of residual stress decreasing.