Effects of Melt Pool Size on Transient and Residual Stress in DMD Process

摘要

A self-consistent transient 3D model is developed tornpredict thermal behavior in Direct Metal Depositionrn(DMD) process, and the obtained results from thernnumerical model are used to predict transient andrnresidual stresses with a commercial software packagernABAQUS. Temperature field and stress formationrnduring the DMD process determine residual stress thatrnis directly related to fracture and fatigue behavior ofrnthe products. The convection in melt pool influencesrnthe overall heat and solute transfer during the process,rnand the fluid flow determines temperature profile atrnthe solidification front. Therefore, residual stressrndistribution can be altered by different melt poolrngeometry with different processing variables such asrnlaser power and scanning speed. In this study, we firstrnperform an investigation of how the residual stress inrnDMD process is developed with time. The laser powerrnis then varied to examine the effects of the power onrnthermal behavior such as melt pool size andrntemperature field. Lastly, we analysed how thermalrnbehaviors with different laser power change thernresidual stress.