Numerical and Experimental Characterization of Melt Pool in Laser Powder Bed Fusion of SS316l

Laser powder bed fusion (LPBF), also called selective laser melting, is an additive manufacturing technology with great potential for creating three-dimensional metallic components with intricate designs. The application of dynamic thermal cycles involving melting and cooling makes it difficult to maintain the desired surface quality and shape in the LPBF process. The LPBF process's dynamic stability of the melt pool is essential to ascertain due to its influence on the quality of the manufactured products. Examining the thermal behavior and temperature distribution inside the melt pool is necessary. Subsequent to experimental validation, employing a finite element model (FEM) has the potential to accurately define thermal distributions and the dimensions of the melt pool. A three-dimensional transient model based on a moving Gaussian heat source was employed in this study to examine the influence of process variables (i.e., scan velocity, laser power, laser beam radius, hatch spacing, number of layers, and scan angle for each layer) on the melt pool shape in LPBF of SS316L powder. A finite element model based on three-dimensional parameters was proposed to evaluate the temperature gradient and melt pool characteristics of SS316L when subjected to laser powder bed fusion. The method takes into account the effect of the laser penetration depth on the characteristics of the molten pool, determined by a multiple-layer (15) and multiple-track (6) finite element model with variable process parameters, such as laser power, scanning speed, beam radius and hatch spacing. Experimental data obtained from the literature were used to calibrate the proposed heat source model, and the adjusted finite element model was then validated through further experiments. The modeling results showed concordance with the experimental data. The effects of the interlayer and intertrack were examined. Temperature distributions for each track and layer and the depth, width and length of the melt pool were evaluated, and the observed values for each variable were analyzed. The average melt pool length, width, and depth were determined to have relative errors of 1.88%, 1.49%, and 2.12%, respectively, between the FEM model and experimentally measured dimensions for an optimal range of varied process parameters.