Effect of Si on Cementite Morphology and Hydrogen Embrittlement Resistance of Tempered Martensitic Steels

This study investigates the influence of Si on cementite morphology and hydrogen embrittlement behavior of tempered martensitic steels. Si promotes the formation of short rod-like and spherical cementite, while reducing the occurrence of film-like cementite. This morphological change decreases hydrogen trapping and enhances resistance to hydrogen embrittlement. Cracks tend to initiate at the tips of film-like cementite, which is more common in steels with lower Si content. Therefore, higher Si content reduces the likelihood of crack initiation and growth by minimizing the presence of film-like cementite. These findings indicate the importance of Si in altering cementite morphology and improving the resistance of tempered martensitic steels to hydrogen embrittlement.