On the connection of the heat input to the forming quality in wire-and-arc additive manufacturing of stainless steels

WAAM (wire-and-arc additive manufacturing) is recently gaining much interest for the fabrication of parts with wide size. A crucial issue associated to this technology is how to control the process variables to achieve expected qualities of parts. The aim of this investigation is to explore the relationship of the heat input (Q) with the forming quality of 308L stainless steel. The outcomes demonstrate that the heat input has significant effects on the shape, microstructures, and mechanical properties of the walls. Both the height and width of single weld beads increase with an increment in Q. The walls fabricated with the low heat inputs feature better mechanical properties and lower surface roughness. The tensile strengths (YS0.2% and UTS) and the surface roughness (Sa) of the walls built with the lower heat input (230 J/mm) are 292 ± 4.95 MPa, 523 ± 4.24 MPa, and 106 μm, respectively, whilst YS0.2% = 273 ± 4.34, UTS = 482 ± 5.66 MPa, and Sa = 179 μm for the wall fabricated with the higher heat input (576 J/mm). This investigation contributes to enriching the understanding on the WAAM process of steels and helping operators to select a proper heat input for specific applications.