应力腐蚀性能的影响
(中南大学 粉末冶金国家重点实验室, 长沙 410083)
摘 要: 研究了近固溶度高温预析出工艺对抗应力腐蚀性能较差的中强可焊7A52和仿7039合金的组织、 时效硬化和应力腐蚀性能的影响。 显微组织观察、 力学性能分析及应力腐蚀性能测试结果表明： 近固溶度高温预析出处理可使合金在晶界形成不连续的析出相； 在保持合金强度、 塑性的同时， 预析出可提高抗应力腐蚀性能， 但预析出温度过低， 合金强度呈下降趋势； 固溶后于400 ℃预析出处理在峰值时效状态下可使7A52铝合金强度和抗应力腐蚀性能得到最佳组合， 抗应力腐蚀性能达到三级时效后的效果。
关键字: Al-Zn-Mg合金; 近固溶度预析出; 组织; 力学性能; 应力腐蚀性能
（ State Key Laboratory of Powder Metallurgy, Central South University,
Changsha 410083, China）
Abstract: The effects of near-solvus high-temperature pre-precipitation on the microstructure, age hardening and stress corrosion cracking of 7A52 and quasi 7039 aluminum alloys were investigated. After analyzed by optical and transmission electron microscope, it is shown that the near-solvus pre-precipitation can be limited to grain boundary and can enhance the discontinuity of grain boundary precipitates in the sequent age. The stress corrosion cracking resistance can be improved with non-deteriorated strength and plasticity via the high-temperature pre-precipitation. The optimum combination of strength and stress corrosion cracking resistance in peak-aging temper can be obtained for 7A52 alloy after pre-precipitation treatment at 400 ℃. The stress corrosion cracking resistance at peak-aging temper can match the same effect with retrogression and re-aging Treatments by the high-temperature pre-precipitation.
Key words: Al-Zn-Mg aluminum alloy; near-solvus pre-precipitation; microstructure; mechanical property; stress corrosion cracking
