Unique Microstructural Features Developed during Selective Laser Melting of CrCoMo Alloy and 316L Austenitic Stainless Steel

摘要

Selective laser sintering (SLS) or laser melting (SLM) is capable of processing a wide range ofmaterials such as metals, alloys and ceramics. In this work Austenitic stainless steel 316L andCrCoMo alloy parts were fabricated by SLM. Samples were characterized using scanning andtransition electron microscopy (SEM/TEM). The observed experimental evidences clearlyshowed development of non-equilibrium microstructure. Local kinetics and thermal historieslead to formation of complex heterogenuos microstructure. Compositional fluctuation and Mosegragation formed the fine cellular sub-grains which were in the size of 0.5 μm. Electron backscattering diffraction (EBSD) demonstrated formation of the cellular sub-grains inside largergrains and confined by the large grains. The sub-grains exhibited slightly differentcrystallographic orientation. High concentration of dislocations at the sub-grain boundaries wereseen which was due to the enrichment of misplaced Mo in an Austenite lattice.