Fatigue crack growth behavior of selective laser melted martensitic stainless steel.

[Display omitted] • Anisotropic FCG of SLM AISI 420 in two build directions was studied. • FCG resistance is greater for loading direction parallel to the build direction. • FCGR difference between two build directions decreased after post-tempering. • Elongated cellular structure dominated anisotropy of FCG behavior. • Tempered martensite had greater effects on FCGR of perpendicular direction. This study investigated the fatigue crack growth (FCG) behavior of selectively laser-melted AISI 420 martensitic stainless steel built in two directions. The effect of tempering treatment at 400 °C was considered. In both as-built and tempered conditions, the parallel orientation exhibited lower fatigue crack growth rates (FCGRs) than the perpendicular orientation, indicating an anisotropic FCG behavior. Tempering treatment moderately reduced the anisotropy of FCG behavior, as the difference in FCGR between the two build orientations decreased in the tempered state. The anisotropic FCG behavior was attributed to the interaction between the crack path and the elongated cellular structure. Tempered martensite had a greater influence on the FCGR of the perpendicular group over the parallel group in tempered state. [ABSTRACT FROM AUTHOR]