Neutron Diffraction Measurement of Residual Stress in High Melting Point Metals Processed by 3D Printing

Abstract

Recently metal 3D printing technology has been considered as one of the most innovative manufacturing technology due to its various advantages. In particular, there have been urgent needs for technology using high melting point metal (HMPM) for the extreme environmental applications such as defense weapon, aerospace rocket, power plant. In this study, we conducted feasibility test for fabrication of Mo and W alloys using direct energy deposition (DED), which is one of the major additive manufacturing (AM) technologies. It is of great concern that the as-processed HMPMs are expected to have significant residual stress due to the use of high laser power in the 3D printing process. So we measured the residual stress and microstructure of Mo and W alloys processed by DED using non-destructive neutron diffraction method. The result demonstrated that the residual stress in the as-processed HMPMs is not significant raging form -100 to 200 MPa regardless of the high applied heat input due to the low thermal expansion and stress relief caused by intergranular micro-cracking. Key words: 3D printing, Direct energy deposition, High melting point metal, Residual stress, Neutron diffraction