X70管线钢管环焊接头氢脆敏感性研究

针对X70管线钢管环焊接头进行12 MPa总压、0.36 MPa氢分压下的缺口拉伸试验，研究焊接接头的氢脆敏感性变化，并结合断裂韧性试验和疲劳裂纹扩展速率试验对其的断裂韧性和裂纹扩展行为进行了研究。结果表明，热影响区位置的断面收缩率下降较明显，表现出较高的氢脆敏感性；与常温常压空气中的原始数据相比，X70钢热影响区在0.36 MPa氢分压环境下的裂纹尖端张开位移（CTOD）值下降了9.6%，断裂表面未出现二次裂纹；X70钢热影响区的疲劳裂纹扩展速率与空气环境相比增加了一个数量级，说明氢气能够增大材料的疲劳裂纹扩展速率，但根据实际管道压力波动情况，在0.36 MPa氢分压条件下X70钢管的氢脆敏感性较小。

Study on Hydrogen Embrittlement Susceptibility of X70 Pipeline Steel Pipe Girth Welded Joints

The notch tensile test under 12 MPa total pressure and 0.36 MPa hydrogen partial pressure was carried out on the X70 pipeline steel pipe girth welded joint to study the change of the hydrogen embrittlement sensitivity of the welded joint, and its fracture toughness and crack growth behavior were studied by combining the fracture toughness test and fatigue crack growth rate test. The results showed that the reduction of area in the heat affected zone decreased significantly and showed a high sensitivity to hydrogen embrittlement. Compared with the original data in air at normal temperature and pressure, the crack tip opening displacement (CTOD) of X70 steel in the heat affected zone under 0.36 MPa hydrogen partial pressure environment decreased by 9.6%, and no secondary cracks appeared on the fracture surface. The fatigue crack growth rate in the heat affected zone of X70 steel is an order of magnitude higher than that in the air environment, indicating that hydrogen can increase the fatigue crack growth rate of materials. However, according to the actual pipeline pressure fluctuation, the hydrogen embrittlement sensitivity of X70 steel pipe is relatively small under the condition of 0.36 MPa hydrogen partial pressure.