Methods for residual stress reduction in additive manufacturing processes

Abstract

A method for additively manufacturing an article includes providing or obtaining a build material, directing a first energy beam at the build material to raise the temperature of the build material above a melting point of the build material, and thereafter withdrawing the first energy beam to allow the build material to solidify into a first layer. The method further includes directing a second energy beam at the first layer, wherein the second energy beam differs from the first energy beam in that the second energy beam is of insufficient energy to cause melting of the first layer of build material and after directing the second energy beam at the first layer, providing additional build material over the first layer. The second energy beam will have an effect of reducing or eliminating residual stresses of each build layer. The energy of the second energy beam can be controlled using a thermal or optical feedback loop. Still further, the method includes directing a third energy beam at the additional build material to form a second layer that is metallurgically fused with the first layer. The process is repeated until an entire 3D shape of desired geometry is completed resulting in a part with reduced of free of residual stress or the potential of cracks within the 3D shape.