X70管线钢及焊缝在模拟煤制气含氢环境下的氢脆敏感性

通过氢渗透测试、氢扩散模拟以及氢含量测试技术研究X70钢在模拟4 MPa总压,0.2 MPa氢气分压煤制气环境下的充氢过程,并通过冲击韧性测试、裂纹扩展测试以及缺口拉伸和慢应变速率拉伸测试方法,从不同角度分析X70钢母材和焊缝组织在模拟煤制气含氢环境下的力学性能.结果表明,在总压4 MPa,0.2 MPa含氢煤制气环境中,X70钢表面存在吸附氢原子并能扩散进入X70钢内部,达到稳态后内部的可扩散氢质量分数为1.9×10-7;与空气中的原始性能比较,X70钢焊缝和母材的冲击性能、缺口拉伸和慢应变速率拉伸强度、塑性以及材料的损伤容限均未发生下降;在实验煤制气环境中,X70钢具有较低的氢脆风险. 

Hydrogen embrittlement susceptibility of the X70 pipeline steel substrate and weld in simulated coal gas containing hydrogen environment

The diffusion and accumulation behaviour of hydrogen in X70 pipeline steel were investigated via hydrogen permeation test, hydrogen diffusion simulation, and hydrogen content test technology in a simulated coal gas environment (4 MPa total pressure, 0.2 MPa hydrogen partial pressure). The mechanical properties of the X70 pipeline steel substrate and weld in a simulated coal gas environment were also analyzed through impact toughness test, crack propagation test, notch tensile test, and slow strain rate tensile test. Experimental results show that hydrogen absorbed on the X70 steel surface in a simulated coal gas environment spreads into the inside of the X70 steel, and the internal diffusion hydrogen mass fraction is 1.9×10-7 after reaching a steady state. Compared with the original performance in air, there is no decline in the impact performance, notched tensile and slow strain rate tensile strength, plasticity, and damage tolerance of the X70 pipeline steel substrate and weld in simulated coal gas. Results show that in a coal gas environment, X70 steel has a lower risk of hydrogen embrittlement.