再时效对过时效7B50合金力学及腐蚀性能的影响

Effect of re-aging on mechanical and corrosion properties of over-aging 7B50 alloy

采用透射电子显微镜观察(TEM)、电化学阻抗谱法(EIS)及力学性能测试等研究不同双级过时效温度下再时效对双级过时效7B50合金显微组织和力学性能的影响,并将双级过时效-再时效处理条件下合金性能峰值点与单级峰时效、双级过时效及常规回归再时效进行显微组织及力学和腐蚀性能的对比。结果表明:再时效可明显提高双级过时效态合金的性能;再时效处理后,合金强度在过时效温度为160℃条件下达到峰值;与单级峰时效相比,双级过时效-再时效峰值条件下,在保持高强度的同时,合金的电导率提高了13.4%,同时断裂韧性也提升12.5%;与双级过时效、常规回归再时效和单级峰时效处理相比,在双级过时效-再时效峰值条件下,合金具有高的抗剥落腐蚀性及低的应力腐蚀敏感性。

The effects of re-aging on the microstructure and mechanical properties of two-step over-aging 7B50 alloy at different over-aging temperatures were investigated by TEM, EIS and mechanical testing, respectively. And the peaking point of two-step over-aging and re-aging treatment was compared with the one-step peaking-aging,two-step over-aging and conventional RRA treatment on the microstructure and mechanical properties. The results show that the property of two-step over-aging alloy is improved significantly through re-aging treatment. The alloy reaches its peaking strength at the over-aging temperature of 160 ℃ during re-aging treatment. Compared with the one-step peaking-aging, the conductivity and fracture toughness of the alloy increase by 13.4% and 12.5%, respectively, at the peaking point of two-step over-aging and re-aging treatment, while the high tensile strength still remains. Compared with the one-step peaking-aging, two-step over-aging, and conventional RRA treatment, the alloy has the highest exfoliation corrosion resistance and the lowest stress corrosion susceptibility at the peaking point of two-step over-aging and re-aging treatment.