Effect of Molten Pool Overlap on Mechanical Properties and Microstructure in Selective Laser Melting AISI 316L SS

Optimizing the molten pool overlap by adjusting the volumetric energy density can improve mechanical properties of the selective laser melting AISI 316L stainless steel (SLM AISI 316L SS) and expand its application prospects in various aspects. The selective laser melting (SLM) technology with different volumetric energy density was used to prepare AISI 316L SS specimens. When the volumetric energy density and molten pool overlap rate reach 138.89 J/mm3 and 69.5%, respectively, ultimate tensile strength, dynamic compressive strength and impact energy of the SLM AISI 316L SS reach 495.81,1195.78 MPa and 125.33 MJ/m3. Hardness value of the cellular structures can reach 2.89 GPa. Scanning electron microscope (SEM) and transmission electron microscope (TEM) were used to characterize molten pools of the SLM AISI 316L SS. Cellular structure size of the overlapping area is larger than that of the non-overlapping area. Cellular structure presents a three-dimensional tubular structure. Main elements Fe, Cr, Ni and Mo of the SLM AISI 316L SS are evenly distributed without significant segregation or agglomeration. Molten pool overlaps affect size of the columnar grain and cellular structure. It is found that molten pool overlap plays a key role in the strengthening of the SLM AISI 316L SS.

Automated summary

Optimizing the molten pool overlap by adjusting the volumetric energy density can improve the mechanical properties of SLM AISI 316L SS and expand its application prospects. Molten pool overlap plays a key role in strengthening SLM AISI 316L SS.