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研究了波动频率对X70管线钢焊接接头在阴极电位下的近中性介质中慢应变速率应力腐蚀开裂(SCC)行为。结果表明,X70钢在波动拉伸载荷和阴极电位(-850 mVSCE)条件下,存在着一定的SCC敏感性。在波动拉伸载荷试验(F-SSRT)情况下,SCC裂纹的扩展机理与匀速慢拉伸试验(SSRT)时的裂纹扩展机理明显不同,SCC裂纹可以从材料表面产生的微孔处萌生并沿主应力面扩展,当载荷波动频率增大到一定程度时,SCC裂纹转变为沿45°最大剪应力面扩展。X70管线钢焊接接头阴极电位下近中性介质中SCC敏感部位为过热区。同时分析了氢在F-SSRT试样SCC过程中的作用和机理。
The behavior of stress-induced cracking (SCC) at low strain rates in near neutral media of X70 pipeline steel welded joints at cathode potential was studied. The results show that there is a certain SCC sensitivity for X70 steel under fluctuating tensile load and cathodic potential (-850 mVSCE). In the case of F-SSRT, the crack growth mechanism of SCC crack is obviously different from the crack propagation mechanism in SSRT. The crack of SCC can initiate from the micro-pores generated on the surface of the material When the frequency of load fluctuation increases to a certain extent, the crack propagates along the 45 ° maximum shear stress plane. X70 pipeline steel welded joints under the cathode potential of nearly neutral medium SCC sensitive parts of the overheating zone. The role and mechanism of hydrogen in the SCC process of F-SSRT were also analyzed.