预充氢1Cr17Ni2钢疲劳裂纹扩展行为研究

Research on Fatigure Crack Growth Behavior of Precharged with Hydrogen 1Cr17Ni2 steel

采用1种自然含氢和5种电化学预充不同含量氢的1Cr17Ni2马氏体-铁素体双相不锈钢CT紧凑拉伸试样进行了室温疲劳裂纹扩展速率实验,并对断裂后的试样断口进行了宏观和SEM分析。结果表明:电化学充氢没有改变试样的稳态疲劳裂纹扩展关系,扩展速率仍符合Paris的幂率关系;随氢含量的增加,疲劳裂纹扩展速率增加;疲劳扩展断口的宏观形貌和微观形貌均与氢含量有关,自然含氢试样的裂纹前沿呈对称的弧形,断口二次裂纹较充氢试样多;随着充氢量的增加,充氢试样裂纹前沿弧线变得越来越平直,断口上二次裂纹越来越少;氢含量较高试样,边缘部位表现为沿晶断裂特征,中心部位及氢含量较低试样断口则为典型的疲劳扩展形貌,可见清晰的疲劳辉纹。

One specimen containing native hydrogen and five kinds of electrochemical precharged with hydrogen 1Cr17Ni2 martensitic-ferritic duplex stainless steel compact type（CT） specimens with different hydrogen content were prepared to investigate fatigue crack propagation rate at room temperature. And the fracture surface of specimens were analysed by using scanning electronic microscope（SEM）. The results indicated that electrochemical hydrogen charging had not changed the steady fatigue crack propagation rate of the specimens,which was still in line with the Paris power law relationship. Fatigue crack propagation rate increased with the increase of hydrogen content. It was also found that both the macro and micro morphology of fatigue fracture were related to the hydrogen content,that was a symmetrical arc occuring at front of cracks for native hydrogen specimen. And with increase of the hydrogen,the arc at front of cracks became more and more straight and the secondary crack became less and less. The edge of fracture for specimen with high hydrogen content presented the intergranular fracture characteristics. However,the fracture was fatigue extended morphology for specimen with low hydrogen content and the fatigue striation could be clearly observed.