Hamed Sheikhbahaee, Ehsan Barati, Mohammad Erfanmanesh, Seyed Masoud Barekat,
Volume 9, Issue 2 (8-2026)
Abstract
This study presents a coupled numerical–experimental analysis of the selective laser melting (SLM) process of AISI 316L stainless steel aimed at achieving minimum porosity (maximum density). A multiscale modeling approach integrates discrete element (DEM), finite volume (FVM), and finite element methods (FEM). First, additive manufacturing parameters were optimized to minimize porosity. Then, using the optimized parameters, DEM simulated powder spreading, followed by FVM for molten pool dynamics. Finally, the optimized parameters were applied in a macro-scale FEM simulation—using the National Institute of Standards and Technology (NIST) AM test artifact—to evaluate part distortion, thermal stress, and porosity. Results indicate the highest distortion occurs at the outer edges (0.9 mm), while the lowest is observed at the center of the top surface. Numerical studies also show that the thermal-stress distribution is complex due to alternating melting and solidification cycles, with maximum stress occurring between layers. The maximum thermal stress at the end of the additive manufacturing process is 750 MPa, and during the process it reaches 910 MPa. The experimental density after final finishing was measured at 99% (1% porosity), in complete agreement with the numerical results. The agreement among computer simulations, analytical predictions, and experimental data indicates this approach can be successfully used to investigate and optimize distortion, stress, and porosity during the SLM process.
M. Safari, I. Dehfouli,
Volume 11, Issue 1 (7-2025)
Abstract
In this study, components made of titanium alloy Ti-6Al-4V are produced using the selective laser melting process. Additionally, effects of laser power, laser scanning speed, and the amount of overlap between adjacent layers on the surface roughness of produced parts are investigated using design of experiment method based on response surface methodology. The results indicate that surface roughness of components created by selective laser melting process first decreases with an increase in laser power and then increases with further increases in laser power. Moreover, increasing the laser scanning speed leads to an increase in surface roughness of produced components. Furthermore, as the overlap of adjacent layers increases, the roughness of produced parts initially decreases and then increases. To achieve components with the least surface roughness, optimization of the process input parameters was conducted, revealing that with a laser power of 150 watts, a laser scanning speed of 500 mm/s, and an overlap amount of 67.8 microns, components made from the titanium alloy Ti-6Al-4V can be produced with a minimum surface roughness of 1.44 microns using the selective laser melting process.
M. Talebipour, R. Shoja Razavi, R. Mozafarinia, M. Barekat, A. Khorram,
Volume 12, Issue 1 (5-2026)
Abstract
Selective laser melting (SLM) has been considered as a method for manufacturing large and complex industrial parts. Considering that structural defects are generally caused by process parameters, the optimal evaluation of parameter selection to minimize localized defects has been of interest. Therefore, a model was presented to predict the optimal single-pass geometric characteristics based on the main process parameters, namely laser power and scanning speed, to prevent defects in single-pass Inconel 738LC on Inconel 738 casting substrate. An optimal process map was obtained based on the use of linear regression method combined with genetic optimization algorithm with optimal combination parameters (PαVβ). Finally, based on the geometric characteristics of single-passes, an optimal region was identified on the process map. At a power of 325 W and a laser scanning speed of 800 mm/s, due to the decrease in the G/R ratio, the microstructure from the junction to the substrate to the top of the single pass has changed from columnar to coaxial dendritic.
