高Cl~-环境对M152和17-4PH高强钢应力腐蚀开裂行为的影响

利用中性盐雾实验、慢应变速率拉伸实验研究M152和17-4PH高强钢在高Cl~-环境中的应力腐蚀行为和机理。结果表明:M152和17-4PH钢在高Cl~-环境中均有一定的应力腐蚀开裂(SCC)敏感性,且随着前期中性盐雾时间的延长,其伸长率逐渐降低,SCC敏感性逐渐升高;通过扫描电子显微镜对试样的断口和侧边裂纹进行观察比较发现,中性盐雾时间的延长会使M152和17-4PH高强钢的断裂机制由韧性断裂向脆性断裂转变。分析得出M152和17-4PH钢在高Cl~-环境中发生SCC是阳极溶解(AD)和氢脆(HE)的协同作用,Cl~-会加速AD过程。经过不同时间中性盐雾后17-4PH钢的SCC敏感性均比M152钢要高,HE作用也越明显。高Cl~-环境中,17-4PH高强钢相对M152钢更易发生SCC。

Effect of High Cl - Environment on Stress Corrosion Cracking Behavior of M152 and 17-4PH High-strength Steels

The stress corrosion cracking (SCC) behavior and mechanism of M152 and 17-4PH high-strength steels in high Cl - environment were studied through neutral salt spray test and slow strain rate tensile (SSRT) test .The result shows that M152 and 17-4PH steels exhibit a certain sensitivity to SCC in Cl- environment ,elongations of them both decrease with the increasing time of early neu-tral salt spray test ,and the SCC sensitivity gradually increases .Comparing the fracture morphology with lateral crack through SEM ,it can be found that the fracture mechanism of M 152 and 17-4PH high-strength steels converts ductile fracture to brittle fracture as the extension of neutral salt spray test time .The synergistic effect of anodic dissolution (AD) and hydrogen embrittlement (HE) result in the occurrence of SCC in high Cl - environment ,and Cl- can promote the AD process .Due to the obvious effect of HE ,17-4PH steel has higher SCC sensitivity than M 152 steel with the same time of early neutral salt spray test .17-4PH high-strength steel is more prone to SCC than M 152 in high Cl -environment.