Revealing the evolution of microstructure and mechanical properties with deposition energy and shielding gas to achieve phase-balanced directed energy deposition of 2205 duplex stainless steel

Abstract

Directed energy deposition-arc (DED-arc) manufactured duplex stainless steel (DSS) has shown great potential for use in marine propellers. However, challenges remain in achieving phase-balanced DSS deposits through the DED-arc process. To overcome this, we conducted a study that involved regulating the deposition energy and shielding gas with the use of ER2205 wire. The results show that the austenite content in DSS deposits increases with the increase of deposition energy, and the content in the Ar+2%N2-protected deposits is significantly higher than that of Ar+2%CO2-protected deposits. Ultimately, DSS deposits with balanced phase content (austenite content of ∼48.4 %) are obtained at a line energy of 600 J/mm for DED-arc under Ar+2%N2 protection. Unlike the N loss in Ar+2%CO2-protected samples, more nitrogen elements are introduced into the DSS samples by Ar+2%N2 shielding gas. Ar+2%N2-protected samples contain more austenite and exhibit a more homogeneous microstructure, which results in the solid solution strengthening and a significant reduction in the anisotropy of the tensile properties. Furthermore, a more systematic evolution of the microstructure and tensile properties of DSS deposits under the influence of deposition energy and shielding gas is revealed. This study preliminarily obtains the relationship between the DED-arc parameters, microstructure, and tensile properties of DED-arc-fabricated DSS, which will provide an important reference for tailoring microstructure and properties in additive-manufactured DSS.