Influence of forming directions on surface quality of 316L stainless steel produced by selective laser melting additive manufacturing

Different forming directions havesignificant impactonsurface qualityin additive manufacturing.This study is aimed atexploring how different forming directions influencesurface qualityin additive manufacturing. First, experimentswere designed to prepare 316L stainless steelbyselective laser meltingadditivesmanufacturingin different forming directions. Besides, the surfacesof samples manufactured byadditives manufacturingin different forming directions were tested using a 3Dsurface profiler and a scanning electron microscope. In this way, their 3Dprofilemaps, surface roughness values, and scanning electron microscopyimageswere obtained. Furthermore, the surface qualitywascharacterized by four parameters,the maximum height-Sz, the maximum valley depth-Sv, the standard deviation of height-Sq, and the arithmetic average height-Sa.The following results were obtained: (1) Different forming directionscorrespond to close upper surface roughness Savalues, the minimumand maximumvaluesof Sabeing 7.16um and 8.20um,respectively. Sais the smallest among the four parameters(Sz, Sv, Sq, andSa), shows good stability and statistical significance.(2)In the same forming direction, the upper surface roughness values followSz>Sv>Sq>Sa, Szis the largest, exceeding 800um,average value Sais the smallestreaching7.36um.The values of Sq, Sz, and Svvary when theformingdirection changes; specifically, all of them increasewhen the forming direction changes from a verticaldirection toplanarand lateral directionsin turn.(3)In different forming directions, the values ofSz, Sv, Sq, andSavaryon different surfaces(XOY, YOZ, and XOZsurfaces), but their variations are basically similar. Meanwhile, the Sz, Sv, Sq, andSavalues of the free surfacesare at least 10 times greater thanthose of theprinted surface. (4)In the selective laser meltingadditive manufacturing process, it is necessary to reasonably select a forming directionfor parts with different dimensional parameters on each side. High-quality workpiece canbe obtained with a reasonable forming direction.The proposed method serves as referencesfor the selection of forming directionof selective laser melting additive manufacturing and provides a new method to improve the surface quality of partsby additive manufacturing.