Thermo-mechanical modeling and validation of stress field during laser powder bed fusion of AlSi10Mg built part

摘要

Direct metal laser sintering process is a layer based laser powder bed fusion additive manufacturing process used to fabricate near net shape metallic components directly from the metal powders. A high energy moving heat source is utilized to melt and fuse the powders in subsequent layers. During the direct metal laser sintering additive manufacturing process, rapid heating and cooling take place which results in an unexpected change in temperature in the scanned layers. This change in temperature induces thermal stresses in the build part after the accomplishment of the process and it can be destructive to the quality and performance of the build parts which hinders its end-user applications. In the present study, a comprehensive thermo-mechanical model has been developed for the purpose of investigating thermal residual stress in the AlSi10Mg single layer build part during the direct metal laser sintering process using finite element method. Further, the model has validated analytically by measuring the thermal strain. In addition, the effects of scan speed and laser power on the development of thermal residual stresses were investigated. It is found that repeated thermal expansion and contraction in the powder bed leads to the development of thermal residual stress and thermal stain in the build part. The finding of this study will help to optimize the processing conditions for minimizing the thermal residual stress in the build part to enhance its end user application.