用止裂法研究X56G管线钢焊缝金属的应力腐蚀破裂

Study on Behavior of Stress Corrosion Cracking of Pipeline Steel (X56G) Weld Metal by Stop Cracking Method

采用ＣＴ试样在恒位移ＳＣＣ试验机上，测试了Ｘ５６Ｇ管线钢焊缝在混合硝盐溶液中的应力腐蚀抗力和应力腐蚀裂纹扩展速率。试验结果表明：用止裂法代替传统的启裂法可以大大简化ＳＣＣ试验。通过力衰减曲线不仅可以研究材料应力腐蚀裂纹扩展速率ｄａ／ｄｔ，而且可获得ＳＣＣ的临界值（ＪＭＳＣＣ），且ＪＭＳＣＣ是与施加的载荷无关的材料常数。

The resistance and crack propagation rate of stress corrosion cracking (SCC) of pipeline steel(X56G) weld metal in mixed nitrate solution are measuted by the constantdisplacement method with compact tension(CT) spcimens and the results show that it is very simple to use stop cracking method instead of fracture method in the SCC testNot only SC-Crack propagation (da/dt) but also SCC critical value(JMSCC) of researched materials can be obtained from force-decreasing curveIt is proved that JMSCC is a material constant which is irrelevant with applied initial force