Effect of laser power on thermal properties of multimaterial structure Inconel 718 and stainless steel 316L processed by directed energy deposition

Multimaterial structures, together with additive manufacturing, promise the variety of combinations of different materials for attainment of adapted features for specified applications in one manufacturing process. But the thermal properties of these structures remain unexplored. The main intend is experimentally investigation of the structure composed of alternating layers of 316 L stainless steel and Inconel 718 prepared by directed energy deposition. The effect of different laser powers during deposition on thermal properties, such as thermal expansion, specific heat, thermal diffusivity, and thermal conductivity for both materials structure and pure materials in the temperature range up to 700 °C, was studied. All these quantities were measured for both interfaces originated according to the sequence of built layers, and the influence of the interface on thermal properties was examined. Wider transition zone with more efficient composition mixing when 316 L is deposited on the Inco718 layer led to increased thermal diffusivity and conductivity values compared to the other interface. With increasing laser power, the decreases in thermal properties were observed. Cracks were observed at 316 L layers and at the interface when 316 L was deposited on Inconel 718 and are more pronounced with increasing laser power and resulting in negative effect on thermal properties. •When Inco718 was deposited on 316 L, a relatively flat or sharp interface was formed and in reverse order of materials, materials mixing interface was created.•Cracks were observed when 316 L deposited on Inco718 due to lower thermal conductivity.•With increasing laser deposition power, the number of imperfections increased.•Thermal expansion and thermal conductivity are influenced by temperature.•The different interfaces have the effect on thermal properties.