The selec‎tive Laser Melting (SLM) process is an additive manufacturing technique that holds the largest share in the production of metallic components via three-dimensional printing. In recent years, extensive research has been conducted to investigate the effects of processing parameters on the quality of fabricated components. However, given the significance an‎d widespread adoption of this technology compared to other manufacturing methods, as well as the numerous parameters influencing the final part quality, more comprehensive studies are required to fully exploit its capabilities. The present study aims to investigate the influence of scan strategy an‎d scanning patterns on the surface quality of printed components. Specifically, it examines the effects of contour scanning parameters, laser delays, an‎d stripe scan overlap on the surface quality an‎d dimensional accuracy of 316L stainless steel components. The results indicate that contour scanning effectively reduces surface defects, such as irregularities, an‎d enhances surface quality. The laser power an‎d scan speed employed for contour formation are two critical parameters that directly impact the final quality of the components. These parameters are defined in terms of contour linear energy density (LED), which represents the amount of energy applied by the laser per unit length of the powder surface. Increasing the contour LED was found to reduce surface roughness an‎d improve surface quality. The optimal parameters for achieving the lowest surface roughness an‎d the highest quality were 80 W laser power an‎d 200 mm/s scan speed, corresponding to a linear energy density of 0.4 J/mm. Moreover, an analysis of the effects of laser power an‎d scan speed on the thickness of thin-walled structures revealed that higher power leads to a larger melt pool an‎d increased wall thickness, while lower scan speeds further amplify this effect. The minimum wall thickness obtained was 105.7 µm, significantly lower than the typical 300 µm thickness reported in SLM processes. This result demonstrates that precise parameter optimization can enable higher manufacturing accuracy. Additionally, the effect of energy density differences between the contour an‎d core regions was examined. The findings indicate that increasing the contour LED to 150% of the core LED resulted in reduced surface roughness an‎d improved part quality. Furthermore, this study determined that the optimal laser delay time for achieving superior surface quality an‎d minimizing structural defects is 450 µs. This delay effectively reduced discontinuities an‎d internal defects while enhancing the solidification process. However, selec‎ting the appropriate scan pattern an‎d optimizing its parameters also plays a crucial role in minimizing surface defects an‎d improving quality. In another section of this research, the effect of stripe scan overlap was analyzed. Increasing the overlap between stripes up to 40 µm improved part density, reduced porosity, an‎d increased hardness. Under these conditions, a relative density of 99.92% an‎d a hardness of 227.9 Vickers were achieved. Increasing the overlap to this extent contributed to residual stress reduction an‎d enhanced structural integrity. These findings provide valuable insights for various industries, including aerospace, automotive, an‎d biomedical applications, particularly in scenarios where high surface quality an‎d dimensional accuracy are critical.

محسن بدرسماي , علي مالكي

احسان فروزمهر

مهدي كاروان , محسن صفوي