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Wire arc additive manufacturing (WAAM), a welding-based additive manufacturing (AM) method, is a hot topic of research since it allows for the cost-effective fabrication of large-scale metal components at relatively high deposition rates. In the present study, the cylindrical component of low carbon steel (ER70S-6) was built by WAAM technique, using a GMAW torch that was translated by an automated three-axis motion system using a rotation table. The mechanical properties of the component were evaluated by extracting tensile, impact toughness and hardness specimens from the two regions of the building up (vertical) direction. It is found that the tensile properties of the built material exhibited anisotropic characteristics. The yield strength and ultimate tensile strength varied from 333 to 350 MPa and from 429 to 446 MPa, respectively, (less than 5 % variation).

Fabrication of metal parts by wire and Arc Additive Manufacturing (WAAM) has received an increased interest in recent years, as it allows high design flexibility and reduction of material wastage compared to other traditional manufacturing routes. This article compares the effect of heat input on metallurgical characteristics of wire arc additive manufactured low carbon steel cylindrical components fabricated by Gas Metal Arc Welding (GMAW) and Cold Metal Transferred Arc Welding (CMTAW) processes. Firstly, the influence of heat input on the grain size was analyzed. Subsequently, the effect of heat input on the metallurgical characteristics of the cylindrical components was studied along the building direction. The microstructure of the built cylindrical-walled component varies from the top to the bottom regions and can be distinguished into two regions: lamellar structures (widmanstatten ferrite and grain boundary ferrite) in the top regions; and equated grains of fully ferrite in the bottom region in GMAW. In the CMT-WAAM cylindrical component samples have been noted two different regions: the bottom region characterized by a ferritic structure with thin strips of pearlite and the top region characterized by a lamellar structure typically bainite with acicular ferrite.

In the current study, a 308L austenitic stainless steel (SS) cylinder was fabricated using the wire arc additive manufacturing (WAAM) technology based on the cold metal transfer (CMT) arc welding process. Response surface methodology (RSM) was used to optimise the process parameters for fabricating the 308L SS component. The microstructural and mechanical properties of the additively deposited 308L SS cylinder were studied. The tensile properties were tested in three directions in relation to the deposition layer to evaluate the anisotropy behaviour of the 308L SS cylinder. The results show that the microstructure of the 308L SS cylindrical component is characterised by vertically growing austenite dendrites (γ) and residual ferrite (δ) within the austenite. The average microhardness of the 308L SS cylinder is about 220 ± 13 HV0.5. The hardness of the lower zone was 6.84% and 13.04% higher than the middle and upper zones. The average values of yield strength (YS), ultimate tensile strength (UTS) and elongation (EL) of the 308L cylinder are 368.5 MPa, 593 MPa and 50.5%, respectively. The UTS of the longitudinal orientation specimen was 3.22% and 6.66% higher than the transverse and diagonal directions. The percentage of anisotropy in UTS was below 10% of the component built with the CMT process. The UTS of the WAAM 308L SS cylinder was greater than 570 MPa and greater than previously reported results. The mechanical behaviour of the CMT-WAAM 308L SS cylinder exhibited equal or better performance than the properties of filler wire and wrought 308L alloy. Therefore, the properties of the CMT-WAAM 308L SS cylinder are confirmed to be acceptable for industrial usage.