Hydrogen distribution and segregation in hydrogen-charged S30408 after fracture analyzed via scanning Kelvin probe force microscopy

Abstract Scanning Kelvin probe force microscopy has employed to investigate hydrogen distribution and segregation in S30408 stainless steel after elongated to fracture. Results reveal that hydrogen-charged S30408 undergoes severe hydrogen embrittlement, and hydrogen-induced cracks occur in martensite (α’) and near the boundaries between α’ and austenite (γ). Hydrogen gathers in the γ near the strain-induced α’ due to the excess hydrogen in the α’. Furthermore, many hydrogen atoms are trapped in α’. The hydrogen segregation in α’ or near the phase boundaries between α’ and γ is one of the reasons for the cracks appearing at these positions.