A study on wire arc additive manufacturing of 308L austenitic stainless steel cylindrical components: Optimisation, microstructure and mechanical properties

Abstract

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.