X80管线钢在近中性pH溶液中的应力腐蚀开裂

采用电化学动电位扫描技术、慢应变速率拉伸(SSRT)试验和扫描电镜观察研究了X80管线钢及焊接接头在NS4溶液中的应力腐蚀行为.电化学实验结果显示,X80管线钢及焊接接头在NS4溶液中的极化曲线具有典型的活性溶解特征.SSRT试验结果表明,随着外加电位的负移,断裂时间、断面收缩率、应变量都明显变小,X80管线钢及焊接接头的应力腐蚀开裂敏感性增加,应力腐蚀断口呈现穿晶准解理特征.施加相同外加电位时,焊接接头较母材的应力腐蚀敏感性增加,其断裂位置全部落在焊缝或HAZ处.

Stress Corrosion Cracking of X80 Pipeline Steel in Near-Neutral pH Values Solutions

The stress corrosion cracking (SCC) behaviors of X80 pipeline steel in near-neutral pH solutions were studied using electrochemical potentiodynamic scanning,slow strain rate tension(SSRT) and scanning electron microscopy.Electrochemistry test results showed the polarization curves of X80 pipeline steel and welded joint in NS4 solutions have typical characteristics of active dissolution.SSRT result showed that with the negative increase of potential,the cracking time,reduction of area and dependent variable all decrease obviously,the sensitivity for SCC increases,and the cracking mode was transgranular with the feature of quasi-clea-vage.When the applied potentials of welded joint and base metal were the same,the welded joint was more sensitive than base metal in SCC.The results showed that all tensile test specimens crack in weld metal and heat affected zone(HAZ).