Mechanical properties and microstructure of hybrid-manufactured 316 L using PBF-LB/M and DED-Arc/M

Additive manufacturing of metal components offers a high potential for many industrial applications due to the cost-efficient manufacturing of geometrically complex and individualized components, for example, to manufacture connections for steel constructions. Different process classes of metal additive manufacturing exist. The powder bed fusion and the directed energy deposition processes are especially relevant for industrial applications. In comparison, the powder bed fusion processes achieve a higher accuracy but have a lower build rate than directed energy deposition processes. This publication focuses on the combination of powder bed fusion of metals using a laser beam and directed energy deposition using a plasma arc for the fabrication of 316 L stainless steel. The differences in temperature profiles and solidification conditions between the two processes cause variations in the microstructure of the 316 L material. These microstructural differences lead each processed version of 316 L to develop distinct properties. The microstructure and mechanical properties were investigated in detail. All tensile specimens failed away from the interface. The integral tensile properties were in between the values of the individual materials. The microstructure showed five different zones. These were attributed to the different thermal characteristics of the two processes and the effect of the heat input of the directed energy deposition additive manufacturing on the powder bed fusion material, which was fabricated first. The results give insight into the differences in the metallurgical and mechanical properties of 316 L manufactured by these two processes. The results also highlight the importance of characterizing the process and material combination for applying a hybrid additive manufacturing process routine.