On hydrogen-induced Vickers indentation cracking in high-strength steel

The present study investigates hydrogen embrittlement cracking (HEC) upon Vickers indentation in a high-strength steel. When an indentation test is applied to the high-strength steel, i.e., steel that has absorbed hydrogen, several cracks appear around the impression, whereas as-received steel with no hydrogen absorption does not produce any cracks. An experimental/computational framework is used to elucidate the mechanism of such indentation cracks caused by hydrogen embrittlement. We use the acoustic emission technique (AET) to clarify at which point during the test the crack initiates. In parallel with the experiment, finite element analysis (FEA) is carried out in order to compute the stress field around the impression. Based on the combined results, we discuss the mechanism of crack initiation and the critical stress required to nucleate the crack. The findings of the present paper may be useful for characterizing local contact fracture properties, which are often seriously deteriorated by hydrogen embrittlement.