管线钢应力诱导型氢致开裂分形试验

以酸性气田集输管网中16MnR 和20 号钢为研究对象,开展应力诱导型氢致开裂分形试验,以验证相关理论模型的正确性。试验制备了两种管线钢的双悬臂梁试件,并将其浸入不同H2S 体积摩尔浓度的腐蚀溶液环境中,通过断口数据取样分析及计算,验证了管线钢氢致开裂的断口形貌具有分形特征,以及应力强度因子与分形维数具有对数正比趋势的关系,同时验证了氢致开裂判据模型、氢致开裂分形扩展速率模型、氢致开裂分形物理机制模型的正确性,可为在役管道氢环境下的裂纹扩展速率的预测提供参考依据。

Fractal experiment on stress oriented hydrogen induced cracking of pipeline steel

In this paper, a fractal experiment of stress oriented hydrogen induced cracking was carried out on the steel 16MnR and steel 20 of the gathering pipeline network in a sour gas field to verify the correctness of the relevant theoretical models. In the experiment, double cantilever beam specimens of the two steels were prepared and then immersed in the H2S corrosion solutions with different volumetric molar concentrations. Finally, the fracture data was sampled for calculation and analysis. It is verified that the fracture morphology of pipeline steel hydrogen induced cracking has fractal characteristics, and the relationship between the stress intensity factor and the fractal dimension follows a logarithmic proportional trend. What’s more, the hydrogen-induced cracking criterion model, the hydrogen-induced cracking fractal propagation rate model and the hydrogen-induced cracking fractal physical mechanism model are verified to be correct. The research results can provide a reference for the prediction of crack growth rate in hydrogen environment of the in-service pipelines.