Research On Solidification Mechanism And Heat Treatment Of Laser Melting 316L Stainless Steel

Laser Addictive Manufacturing(LAM) technology is an emerging laser aided manufacturing technology based on a new additive manufacturing principle, which combines laser cladding with rapid prototyping into a solid freeform fabrication process that can be used to manufacture near net shape components from their CAD files. In the present study, Laser Addictive Manufacturing technology was successfully used to fabricate a series of samples of AISI 316 L steel coating on an AISI 304 L steel substrate. The structure of the deposits were investigated using optical and scanning electron microscopy, Electron Backscattered Diffraction and Residual Stress test. The microstructure has been found to be coarse columnar grains in nature, which grew epitaxially from the substrate. The solidification mechanism and the inducement of sub-grain microstructure of Laser Addictive Manufacturing AISI 316 L steel is investigated. The influence of the strong marangoni convection to solidification is discussed with Marginal Stability and cell convection theory. Stress in the coating was relieved by low/medium temperature and long term heat treatment. The microstructure and static recrystallization of the heat treated samples are investigated using optical and scanning electron microscopy, Electron Backscattered Diffraction and the residual stress level of heat treated samples is discussed.