Metal Additive Manufacturing Conference 2019

A manifold variety of additive manufacturing techniques has a significant positive impact on many industry sectors from small scaled medical applications to overhaul applications on large-scaled machine components. Large components are often manufactured via laser metal deposition (LMD) instead of using powder bed based processes. The advantages of LMD process are a high build-up rate with values up to 300 cm³/h and a nearly limitless build-up volume. In combination with the lightweight material aluminium it is possible to manufacture large lightweight components with geometries adapted to customer requirements in small batches. This contributes the pursuit of higher efficiency of machines through lightweight materials as well as lightweight design. A low-defect additive manufacturing of high strength aluminium EN AW-7075 powder via LMD is an important challenge to concern. During the process a considerable proportion of pores up to over 10% can build and weakens the mechanical properties. Additionally, the heat input affects the hardness of the manufactured part. A higher hardness could be reached through artificial aging in two steps after the LMD-process. The rapid solidification of the melt pool produces a supersaturated solid solution, which undergoes precipitation hardening during artificial aging. A significant reduction of pore volume can be achieved by a higher energy input per unit length and an improved shielding gas flow. Therefore, a shielding gas shroud was developed to keep hydrogen from the air away from the process zone. The combination of the improved shielding gas flow with a high energy input per unit length led to a decrease of pore volume from over 7% to lower than 1.5%.