T6时效和T6I6时效对6005A铝合金微观组织和性能的影响

采用硬度测试、晶间腐蚀试验,透射电镜(TEM)和高分辨透射电子显微(HRTEM)分析研究6时效和T6I6时效工艺处理对6005A铝合金硬度和晶间腐蚀性能的影响。结果显示:6005A铝合金经T6峰时效175℃、12 h后,虽然硬度达到了120 HV,但存在严重的晶间腐蚀倾向,腐蚀深度约为100μm,同时,晶界上的析出相呈不连续分布,尺寸较小;经T6I6时效处理后,晶内生成细小的析出相,同时晶界的析出相呈不连续分布,但尺寸较大,此时合金可获得更高的峰值硬度(127 HV),而且其抗腐蚀能力得到显著提高,腐蚀深度约为30μm。

Effects of T6 and T6I6 ageing treatments on microstructure and properties of 6005A aluminum alloy

The effects of T6 and T6I6 ageing treatments on the hardness and intergranular corrosion properties of 6005A aluminum alloy were investigated using hardness test,intergranular corrosion(IGC) test,transmission electron microscopy(TEM) and high resolution transmission electron microscopy(HRTEM) analysis.The results show that the hardness of the alloy in the T6 ageing treatment approaches a maximum value of 120 HV,however,it presents a severe intergranular corrosion with an average corrosion depth of 100 μm.The precipitates with small size are discontinuous at the grain boundaries.Fine precipitates with high density can be obtained in the grains after T6I6 aging treatment,and the precipitates are still discontinuous in the grain boundaries,however,the size of the precipitates is larger than that under T6 ageing treatment.The T6I6 ageing treatment for 6005A aluminum alloy not only increases the maximum hardness(127 HV),but also enhances the intergranular corrosion resistance,and the corrosion depth is only about 30 μm.