Mechanical behavior of additive manufactured AISI 420 martensitic stainless steel

This study investigates the mechanical behavior of laser-cladded and additively manufactured AISI 420 martensitic stainless steel (MSS) in the longitudinal and transverse direction. Microstructural features were characterized using scanning electron microscopy (SEM) and electron back-scattered diffraction (EBSD) techniques. EBSD analysis was also used to measure the grain size and volume fraction and distribution of each phase present. The mechanical testing results revealed anisotropic mechanical properties in both longitudinal and transverse directions. To address the anisotropic issue, post-cladding heat treatment was proposed. It was shown that the post-cladding one-hour heat treatment at 565 degrees C effectively eliminated the anisotropic behavior of the laser-cladded 420 stainless steel. Furthermore, as an alternative solution, cross-layered as well as angular powder deposition were studied. The AM sample built at angular powder deposition (30 degrees) against the horizontal base improved the mechanical properties and minimized the directionality challenges.