Keynote Speaker (by invitation only) at Digital Twin Symposium 2019, presented by Dongdong Gu
Due to the point-by-point, line-by-line and area-by-area localized forming characteristics of laser additive manufacturing (LAM) process, it is necessary to carry out the microscopic - mesoscopic - macroscopic cross-scale structure and performance control of LAM of metal components, in order to realize the effective control of typical metallurgical defects such as balling effect, porosity, deformation, and cracks. In this presentation, the selective laser melting (SLM) additive manufacturing of aluminium-based and nickel-based components was performed. In the mesoscopic scale, the thermodynamic behavior of the laser melting / solidification of the metal powder was disclosed and the formation and inhibition mechanisms of balling effect were revealed. In the microscopic scale, the evolution of surface tension of the melt in the molten pool and the mechanism of bubble motion and melt densification were clarified. In the macroscopic scale, the thermal mechanism, stress formation and performance control of LAM processed components were proposed. This presentation provides the physical basis and key process control methods for the structure and performance control of high-performance metal components by LAM.