The role of delta ferrite in hydrogen embrittlement fracture of 17-4 PH stainless steel

The role of 8-Fe in hydrogen embrittlement (HE) of 17-4 PH steel is studied in this work. Scanning Kelvin probe force microscopy result indicates that 8-Fe is a hydrogen trapping site. Accordingly, 8-Fe can reduce the hydrogen concentration of surrounding martensite and prior austenite grain boundaries (PAGBs) and imped the brittle fracture along lath boundaries and PAGBs, which can be beneficial to the HE resistance improvement. How-ever, a cleavage fracture of 8-Fe can occur under the synergetic action of hydrogen -enhanced localized plasticity (HELP) and hydrogen enhancement of the strain-induced generation of vacancies (HESIV). These findings indicate a new path to improving HE resistance of high strength martensitic steels.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

The role of 8-Fe in hydrogen embrittlement of 17-4 PH steel was studied. It was found that 8-Fe can reduce hydrogen concentration, impede brittle fracture, and provide a new pathway to improve HE resistance in high strength martensitic steels.