Hydrogen-assisted damage in austenite/martensite dual-phase steel

Figure 1: Non-deformed steel microstructure and corresponding hydrogen distribution. (a) Optical micrograph. (b) ECC image showing twins in martensite. SEM images showing silver particles (white) at (c) low and (d) high magnifications
Localized diffusible hydrogen in martensite causes cracking through two mechanisms: (1) interaction between {1 1 0}M localized slip and {1 1 2}M twin and (2) cracking of martensite–martensite grain interfaces. The former resulted in nanovoids along the {1 1 2}M twin. The coalescence of the nanovoids generated plate-like microvoids. The latter caused shear localization on the specific plane where the crack along the martensite/martensite boundary exists, which led to additional martensite/martensite boundary cracking.