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

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.