Investigation of surface quality, microstructure, deformation mechanism, and fatigue performance of additively manufactured 304L stainless steel using grinding

Ground 304L stainless steel (SS) made by laser powder bed fusion (LPBF) process was comprehensively investigated from the aspects of surface integrity, residual stress, microstructure, and mechanical properties. The experimental results indicated that grinding substantially improved the surface quality characteristics and significantly increased the fatigue life by more than two times. The removal of LoF (Lack of fusion) defects and keyholes near the as-built surface plays a critical role in improving fatigue performance due to the enhancement of fatigue crack initiation resistance. In addition, the ground subsurface cracks and newly formed lath-like grains were discovered in ground LPBF 304L SS, and their formation mechanisms were discussed with the aid of electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). This work brings new insights into the underlying principles of improving the mechanical properties of LPBF metallic materials through high-efficiency grinding.

Automated summary

This study comprehensively investigates the surface integrity, residual stress, microstructure, and mechanical properties of 304L stainless steel made by laser powder bed fusion process. The results show that grinding significantly improves the surface quality characteristics and increases the fatigue life. Additionally, ground subsurface cracks and newly formed grains were observed, and their formation mechanisms were discussed.