恒位移条件下X70钢在硝酸盐环境中的裂纹扩展行为

摘要

采用楔形张开加载(W0L)预裂纹试样应力腐蚀试验方法,研究了X70管线钢在NO3--H2S-Cl-复杂介质中的裂纹扩展速率.结果表明,X70钢在近中性800g/L NaNO3及NaNO3-H2S-NaCl环境下裂纹扩展速率均较低;在同种环境下,Kli近似相等时,X70钢的裂纹扩展速率da/dt大小关系为焊缝区大于母材;X70钢母材及焊材在H2S-Cl-中的裂纹扩展速率略大于在NO3--H2S-Cl-中的速率.图8表4参11%WOL test method was adopted to conduct experimental research on crack propagation rate of X7O pipeline steel under complex medium condition of NO3--H2 S-Cl-.The results show that the crack propagation rates of X70 WOL specimen are relatively low in the near-neutral 800 g/L NaNO3 environment or containing NaNO3-H2 S-NaCl; In the experimental environment at approximately equal Kli, the order of magnitudes of crack propagation rate da/dt of X70 steel is weld zone ＞ masterbatch; The crack propagation rate of X70 srteel masterbatch in H2 S-Cl- is slightly higher than those in NO3--H2S-Cl-.[Ch,8 fig.4 tab.11 ref.]