A Review on Residual Stress in Metal Additive Manufacturing.

A new method for producing parts in the expanding sector is additive manufacturing. The appropriate name for three-dimensional (3D) printing is additive manufacturing because it produces the part layer by layer. Plastics and metals can be 3D printed in large quantities with the precise surface finish and feature quality needed in additive manufacturing. More specifically, direct metal sintering, direct energy deposition, and metal binder jetting are used in 3D printing. The computer-aided design model is completed when the powder bed has been successively scanned and lowered. The metal sintering process uses a powder bed with powder metal, and laser selectively melts a flattened bed of powder, which is done with roller with successive rolling of new layer on previous into desired shape before a new layer is pushed on top of the previous layer. As a result, the new layer has solidified on top of the earlier layer, causing the prior layer to melt back again. Because of the unique thermal cycle, this results in residual stress (RS). The unique thermal cycle of metal additive manufacturing is characterized by (1) rapid heating rate caused by high energy intensity and steep temperature gradients; (2) rapid solidification with high cooling rates because of the small volume of melt pool; and (3) melt back, which involves simultaneous melting of the top powder layer and re-melting of underlying previously solidified layers. The presence of RS in metal additive manufacturing (AM) creates difficulties that restrict the process's ability to produce parts at an industrial scale. During and after manufacturing, these forces may cause parts to distort and crack. This can be solved by heating the powder bed, which will lessen this type of issue. The causes, traits, and reduction of RS are the main topics of this review article. A number of conceptual approaches to reducing RS are addressed to provide some useful inspiration for creating a methodical RS balancing procedure for AM. These approaches are based on the state and future of the relevant techniques.