Ultrasonic additive manufacturing of steel: Method, post-processing treatments and properties

Ultrasonic additive manufacturing (UAM) was applied to fabricate laminated carbon steel structures. The feasibility of UAM to manufacture low-alloy carbon steel samples was proven. Interface investigation of the UAM parts was conducted by SEM, EBSD and TEM analysis. Multiple defects at the interfaces of the as-printed parts were observed. In order to improve the structural homogeneity and mechanical properties of the parts, spark plasma sintering (SPS) and hot isostatic pressing (HIP) post-treatments were applied. As a result, after both treatments, interface defects were healed and the shear strength of the welding interfaces was significantly improved. Treatment by SPS apparatus showed higher shear strength improvements as compared to the HIP treated specimens.