Reliability and sustainability of wire arc additive manufactured plates using ER 347 wire-mechanical and metallurgical perspectives

The steel wall measuring 120 mm in length and 210 mm in height was manufactured by wire and arc additive manufacturing (WAAM) using ER347 wire and gas metal arc welding (GMAW). The mechanical integrity and microstructure of the WAAM treated plate were examined. It was found that the steel plate was well formed, no clear boundaries between the layers were observed, and different thermal history leads to a variety of microstructures. The hardness of the WAAM-processed plate gradually varied from top to bottom and was between 203.5 HV and 248.2 HV. Microstructure of WAAM 347 consists of columnar dendrites and equiaxed dendrite in the multilayer deposition. The percent volume fraction of delta ferrite in the as-deposited WAAM plate was 4.2 and the predicted ferrite number from WRC-1992 diagram is 4.1. The mechanical properties of the welded parts were anisotropic; the sample at 45° orientation has a higher tensile strength compared to 0° and 90° orientation samples. The fractured tensile specimens in the as-deposited state were characterized by dimple-like structures revealing the ductile fracture. SEM line mapping confirms the presence of intermetallic compounds (NbC) in the WAAM 347 plate.