Effect of diffusible hydrogen content on embrittlement of P92 steel

Abstract

In the present investigation, varying electrode conditions (dried and contaminated) have been employed during welding of P92 steel to study the effect of diffusible hydrogen level on hydrogen-assisted cracking (HAC). Shielded metal arc welding process was employed to deposit the metal on a P92 steel plate. To evaluate HAC, the Granjon implant test with varying diffusible hydrogen content in the deposited metal was utilized. The diffusible hydrogen level was measured in the deposited metal by using the mercury method. Lower critical stress (LCS), embrittlement index (EI) and normalized critical stress ratio were evaluated from the Granjon implant test. The fracture surface morphology of fractured implant specimens has been studied by using a field emission secondary electron microscope. The P92 steel plate welded by the contaminated electrode with a high level of diffusible hydrogen was found to be more susceptible to HAC. As diffusible hydrogen content increased in the deposited metal, the LCS value and EI were observed to be decreased.