紧固件用GH4080A合金的应力腐蚀机制

Stress corrosion mechanism of GH4080A alloy for fasteners

采用慢应变速率拉伸实验研究了pH值、SO4^2-、Cl^-对GH4080A合金应力腐蚀行为的影响。结果表明:pH值越低,GH4080A合金的抗应力腐蚀性能越差;合金对中性条件下的Cl^-应力腐蚀敏感性不明显,但pH<7时,合金对Cl^-存在应力腐蚀敏感性,而且对HCl具有明显的应力腐蚀敏感性,主要源于H^+和Cl^-对应力腐蚀的协同作用;常温下GH4080A对含SO4^2-离子的介质不敏感。进一步的外加电位应力腐蚀实验表明,GH4080A合金应力腐蚀断裂机理为氢致开裂型,断口特征表现为沿晶脆性断裂。

The effects of pH value, SO4^2- and Cl^- on stress corrosion behavior of GH4080 A alloy were investigated by slow strain rate tensile test. The results show that the lower the pH value, the worse the stress corrosion resistance of the GH4080 A alloy. Under neutral media conditions, Cl^- has low sensitivity to stress corrosion of the alloy, but when pH<7, the alloy has stress corrosion sensitivity to Cl^- and shows obvious stress corrosion sensitivity to HCl, mainly due to the synergistic effect of H^+ and Cl^- on stress corrosion. The GH4080 A alloy is not sensitive to SO4^2- containing media at room temperature. Further experiments on applied potential stress corrosion show that the stress corrosion fracture mechanism of the GH4080 A alloy is hydrogen-induced cracking type, and the fracture morphology shows the typical intergranular brittle fracture.