预回复对Al-10.78Zn-2.78Mg-2.59Cu-0.22Zr-0.047Sr铝合金组织与性能的影响

The research of the effects of prerecovery to aluminum alloy Al-10.78Zn-2.78Mg-2.59Cu-0.22Zr-0.047Sron microstructure and properties

摘要:

采用电子背散射衍射分析(EBSD)、X射线衍射分析(XRD)、硬度测试、电导率测试、拉伸试验、晶间腐蚀和剥落腐蚀试验,研究了预回复处理(250℃×24h + 300℃×6h + 400℃×6h)对超高强铝合金Al-10.78Zn-2.78Mg-2.59Cu-0.22Zr-0.047Sr组织与性能的影响。结果表明：合金固溶前的预回复处理可以细化合金晶粒,平均晶粒尺寸从7.30 μm减小到5.57 μm；经预回复处理的合金中存在较多的低角度晶界,其比例为0.623。预回复处理对合金的硬度与电导率影响较小,但经预回复处理的合金强度明显提高。峰值时效(120℃×48h)下经预回复处理的合金屈服强度为633.2 MPa,相对未预回复处理的合金屈服强度提高35 MPa。预回复处理对合金的抗晶间腐蚀与剥落腐蚀性能影响较大,晶间腐蚀等级从4级改善到3级；剥落腐蚀等级从EA级提升到PB级。

Abstract:

The effects of prerecovery ( 250℃×24h + 300℃×6h + 400℃×6h ) to aluminum alloy Al-10.78Zn-2.78Mg-2.59Cu-0.22Zr-0.047Sr on microstructure and properties was researched by analysis of EBSD、XRD and test of hardness、conductivity、tensile、intergranular corrosion、exfoliation corrosion. The results show that, prerecovery treatment can refine grain size with average size reduces from 7.30 μm to 5.57 μm and increase the proportion of low angle grain boundary from 0.588 to 0.623. The effect of prerecovery on hardness and conductivity of the alloy is small, but the strength of the alloy is obviously improved by the prerecovery. The yield strength of alloy at peak aging(120℃×48h) processed by prerecovery is 633.2 MPa. Compared with the alloy without prerecovery treatment, the yield strength increased by 35 MPa. The intergranular corrosion and exfoliation corrosion of alloy after prerecovery treatment are improved from rank 4 to rank 3 and rank EA to rank PB respectively.