Issues in fabrication of 3D components through DMLS Technique: A review

DMLS or Direct Metal Laser Sintering is a technique which can be classified under an additive manufacturing (AM). In this technique, metal powders are used to manufacture the parts or components in a layer by layer fashion. This technique is widely adopted by manufacturing industries, aerospace, automobile, naval, biomedical and other industries. Recent developments of high power laser and fiber optics have also enabled DMLS to process the metallic powders in an efficient manner. So far, the DMLS process has encountered several issues or challenges during the operation. This review presents the DMLS operation and the several issues arising during this process. These issues or challenges are metallurgical defects (balling, porosity and delamination), micro structural change and evaluation of mechanical properties such as high residual stress, tension and compression behavior, surface roughness and wear analysis. In this paper, an attempt has been made to address all the issues or challenges arising during the DMLS process. This paper also deals with the significant effect of process parameters on the allied properties of DMLS processed parts. High temperature (or high thermal gradients) along with high cooling rate and further heat treatment associated with the process have a significant impact on the change in microstructural behavior and residual stresses. Thus, different control methods are discussed to tackle all the issues or challenges arising during the process i.e. to alleviate the process defects, regulate the cooling rate and heat treatment to tackle the microstructure, mechanical properties, residual stresses, and corrosion behavior.