Mechanical properties of wire plus arc additive manufactured steel and stainless steel structures

As the imagination, need, and desire for large additively manufactured metallic structures grow across market sectors, so interest in wire plus arc additive manufacture (AM) techniques is growing. Often, the first requirement of a potential new user of AM is knowledge of the mechanical properties of common materials, process accuracy, reliability and productivity, and the implications of these manufacturing parameters on the structural integrity of their application of interest. This paper will examine the use of a robotic gas metal arc welding system to build test structures in the 0.5 m, 20 kg range from low carbon steel and stainless steel, using the wire plus arc additive manufacturing technique. Different approaches to build methodology and their effects on the mechanical properties including yield and tensile strength, impact, fracture toughness, and anisotropy will be examined and interactions and co-relations identified. The technology is shown to be capable of producing steel structures with very high fracture toughness, with some loss of strength, when compared with equivalent parent metal and welds. The specific arc deposition pattern affects both the mechanical properties and the apparent anisotropy in both the carbon steel and stainless steel. The experimental results generated are considered and comments made in relation to their implications for structures manufactured in this manner.