Effect of Double Wire Cold Feed on Characteristics of Additive Manufactured Components

Shaped metal deposition (SMD) using metal inert gas welding plus externally cold wire is a relatively new technology of additive manufacturing, which fabricates near-net shaped parts. It is performed by depositing a main wire plus a cold feed wire melted by the electric arc heat. In the present work, a new experimental set-up was developed, which consists of a MIG-welding source and an external cold wire feed unit plus a 3-axis machine. The main intent of the current paper is to investigate the microstructural and mechanical properties of austenitic stainless steel grade 309L deposited parts. The result showed that the value of the wire feed ratio (WR) plays an important role in both microstructure and mechanical properties. The microstructure mainly consists of two phases ferrite and austenite as predominant phases throughout the parts. Widmansttãten austenite structure that is denoted as (W) this appears in the white region, and Vermicular delta ferrite (V) appears as the dark-etching phase. The tensile test results showed the UTS value increased by 17.36% in the longitudinal direction when using cold feeding, while it increased by 4.39% in the vertical direction. The hardness test results showed that the hardness value increased by 36.23% when using cold feeding. Also, cold wire feeding reduces interpass temperature into the workpiece by 10%.