Multi-metal additive manufacturing of selectively doped 316 L stainless steel-copper composite using hybrid laser powder bed fusion

Abstract

This paper introduces a hybrid laser powder bed fusion method integrated with material jetting techniques for producing 316 L stainless steel (SS)-copper (Cu) composites. Two molecular Cu precursor inks were formulated and evaluated using two distinct jetting systems: ink jetting and pneumatic jetting. The direct conversion of the Cu precursor ink into metallic Cu was studied using laser scanning, adjusting both laser focus and scan speed. Moreover, factors influencing ink conversion, Cu capture rate, and the effective thermal conductivity of the 316 L SS-Cu system are discussed. The thermal conductivity of both as-printed and annealed composite coupons was observed to enhance by 115% and 181% respectively, when compared to wrought 316 L SS at 300 °C. Microstructural analyses revealed the formation of a continuous Cu network during annealing, which further enhanced the effective thermal conductivity of the composite coupons. The microhardness of the composite coupon decreased by up to 26% compared to wrought annealed 316 L SS. Lastly, the potential of producing multi-metal structures using the hybrid LPBF method is demonstrated.