含Sr7085型铝合金的晶间腐蚀和剥落腐蚀性能

Sr addition on intergranular and exfoliation corrosion properties of 7085 aluminum alloy

对一种Sr微合金化的7085型铝合金的晶间腐蚀性能和剥落腐蚀性能进行了研究。结果表明,该合金经均匀化退火、热压缩变形加工、强化固溶(470℃×2 h+480℃×2 h+490℃×2 h)处理、冷水淬火、T6(120℃×24 h)时效处理后,具有很好的抗晶间腐蚀性能和抗剥落腐蚀性能,其抗腐蚀性能明显优于7075-T6合金。按GB 7998-2005(ASTM G110-1992)晶间腐蚀试验标准,该合金未发生晶间腐蚀,仅发生点蚀。按GB/T 22639-2008(ASTM G34-2001)剥落腐蚀试验标准,其剥落腐蚀等级为PA级。该合金所具有的优异抗腐蚀性能与其具有较低的合金元素总量(10.073%)、较高的w(Zn)/w(Mg)(4.97)比和w(Cu)/w(Mg)(1.06)比以及Zr和Sr的微合金化作用(细化组织、抑制再结晶)是一致的。

Intergranular and exfoliation corrosion properties of 7085 aluminum alloy containing Sr were studied.The results show that after annealing,hot compressive deformation processing,enhanced solid solution treatment（470 ℃×24 h＋480 ℃×24 h＋490 ℃×24 h）,water quenching and T6 aging treatment（121 ℃×24 h）,the alloy exhibits superior intergranular corrosion and exfoliation corrosion resistance,which is considerably better than that of 7075-T6 alloy.It is found that,the alloy presents only pitting corrosion rather than intergranular corrosion after intergranular corrosion test,and only PA grade exfoliation corrosion occurs for exfoliation corrosion test.The corrosion resistance of the 7085 aluminum alloy containing Sr is superior to 7075 alloy.It is believed that the excellent corrosion resistance of the alloy is ascribed to the low total amount of alloying elements（10.073%）,the high element ratios of Zn/Mg（4.97） and Cu/Mg（1.06） and the micro-alloyed effects of zirconium and strontium（refining microstructure and improving recryscallization resistence）.