Additive Manufacturing of Thin-Wall Steel Parts by Gas Metal Arc Welding Robot: The Surface Roughness, Microstructures and Mechanical Properties

The Additive Manufacturing (AM), which employs the arc to fuse the metallic wire (WAAM) is attracted much attention for producing metallic parts. This technique shows a high rate of the material deposition and low production costs when compared to other metallic AM technologies. In the current work, an industrial welding robot has been employed for building ER70S6 steel walls according to the additive manufacturing method. First, two deposition strategies were considered to build the thin walls layer by layer—i.e., the same deposition direction and alternating deposition direction strategies. After that, the microstructural and mechanical characteristics of thin walls built with the most suitable strategy were investigated. The results indicate that the alternating deposition direction strategy allows achieving thin walls with more regular height. The roughness of the side surface of the thin walls is about 0.23 mm. The microstructure of ER70S6 thin walls changes from region by region: the upper region consists of lamellar structures; the middle region features granular structures; and the lower region shows mixed lamellar and equiaxed structures. The hardness also varies according to these three regions. The upper region shows the highest average value of hardness (~191 HV), followed by the lower region (~178 HV), and the middle region (~163 HV). Finally, the ER70S6 walls built by WAAM exhibit the anisotropy in terms of tensile strengths in the horizontal and vertical directions. © Springer Nature Switzerland AG 2021.