应变速率对X70管线钢应力腐蚀行为的影响

Effect of Strain Rate on Stress Corrosion Cracking Behavior of Steel API-X70

通过波动拉伸载荷试验(F-SSRT),研究了不同应变速率对X7 0管线钢在阴极电位下近中性介质应力腐蚀开裂(SCC)行为的影响。结果表明:X7 0管线钢在特定的近中性介质中,在波动拉伸载荷和阴极电位(-850 mVSCE)条件下,存在SCC敏感性。在波动拉伸载荷试验条件下,SCC裂纹的扩展机理与匀速慢拉伸试验时不同,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,当应变速率在一定范围时,SCC裂纹转变为沿45°最大剪应力面扩展。还分析了波动拉伸载荷试验中氢在X70管线钢SCC发展过程中的作用和机理。

The stress corrosion cracking（SCC） behavior of API-X70 steel was investigated in a near-neutral pH solution by fluctuant slow strain rate test（F-SSRT）.The test results indicated that the steel API-X70 had certain susceptibility to SCC in specific near-neutral pH solution under fluctuant tension load and cathodic potential（-850 mVSCE）.The fluctuant slow strain rate test（F-SSRT） showed that the mechanism of crack growth was obviously different from that of normal slow strain rate test（SSRT）.The SCC crack was able to start from the tiny hole on the surface, and when strain rate was in certain range, the SCC cracks would propagate along 45 degree direction to the maximum shear stress plane. The effect and mechanism of hydrogen in the course of SCC initation and growth were analyzed.