Achieving enhanced strength and ductility in 316L stainless steel via wire arc additive manufacturing using pulsed arc plasma

Abstract

An innovative wire arc additive manufacturing method using pulsed arc plasma (PAP-WAAM) has been proposed to manufacture high-performance metal parts by effective heat management in our previous study. In general, enhancing the strength of 316L stainless steel (SS) tends to reduce its useful ductility. Here, we reported that 316L SS additively manufactured via the PAP-WAAM method exhibited simultaneously higher strength and ductility than 316L SS fabricated by traditional WAAM based on gas tungsten arc welding (GT-WAAM). The PAP-WAAM 316L SS exhibited a high yield strength (YS) (0.2% offset) of 425 ± 13 MPa and ultimate tensile strength (UTS) of 609 ± 7 MPa, as well as a large elongation (EL) of 45 ± 7%. By comparison, the GT-WAAM 316L SS exhibited relatively low tensile properties, including YS (0.2% offset) of 396 ± 40 MPa, UTS of 585 ± 25 MPa, and EL of 32 ± 3%. High strength is attributed to fine microstructure, high-density dislocations, and low-angle grain boundaries generated during PAP-WAAM, while superior ductility correlates with a steadily high strain hardening rate that originates from the occurrence of abundant deformation twinning. Deformation twinning also contributes to the strength of additively manufactured 316L SS, because the twin boundary can act as a barrier to dislocation slip. This work demonstrates the potential of PAP-WAAM to fabricate high-performance metallic components with superior strength and ductility.