中文摘要：

采用洛氏硬度计、电子拉伸试验机、冲击试验机、透射电镜（TEM）、能谱（EDS）等测试技术对不同时效状态下7175合金的硬度、强度、塑性、冲击韧性、应力腐蚀性能以及晶界附近的化学成分进行系统的分析。结果表明：合金的硬度、强度均具有“双峰”特征；合金的应力腐蚀（SCC）敏感性随时效时间的延长而降低；Mg晶界偏析随时效时间的延长而减少；在第二时效峰状态时合金具有高的硬度、强度、塑性、冲击韧性和抗应力腐蚀性能。运用“相变-Mg—H”理论解释7175合金第二时效峰状态时的高强度、低SCC敏感性机理。

英文摘要：

The hardness, strength, plasticity,impact toughness,SCC susceptibility and the composition in the vicinity of grain boundary of 7175 alloy were investigated by means of Rockwell hardnrss tester, electronic tensile testing machine, impact testing machine, TEM and EDS. It was shown that the hardness and strength both had double peaks. The SCC susceptibility declined with increasing the aging time, and the alloy had higher strength, and lower SCC susceptibility at the second aging peak. In addition, the concentration of Mg segregated to grain boundary decreased with increasing aging time. The mechanism of high-strength and low-SCC-susceptibility for 7175 alloy at the second aging peak was firstly explained by ＂phase transition- Mg-H＂ theory.