Maintaining Excellent Mechanical Properties via Additive Manufacturing of Low-N 25Cr-Type Duplex Stainless Steel

Abstract

Duplex stainless steel (DSS) exhibits good mechanical properties and corrosion resistance, and has attracted more and more attention within the fields of both science and technology. However, the increasing levels of N and of Cr, Mo, etc., as alloying elements in DSS increase production difficulty. In particular, the N element increases the risk of Cr2N precipitation, which can seriously deteriorate the thermal plasticity of DSS, while increasing its strength. For this reason, a low-N-content 25Cr-type DSS was designed in order to adapt additive manufacturing processes. With regard to the nano-inclusions of oxide precipitation and effective grain refinement, and considering the benefits of selective laser melting fabrication, a low-N 25Cr-type duplex stainless steel with a 0.09 wt.% N content achieved high mechanical properties, with a yield strength of 712 MPa and an elongation of 27.5%, while the V-notch impact toughness was 160 J/cm2. The microstructure evolution and the reasons behind the improvement in mechanical properties will be discussed in detail.

Recent Progress in Additive Manufacturing of Alloys and Composites

“…However, the challenges in producing additive-manufactured DSSs are compounded by high levels of nitrogen (N), chromium (Cr), molybdenum (Mo), and other alloying elements. To address these issues, He et al [ 7 ] developed a novel low-N 25Cr-type DSS. This novel low-N 25Cr-type DSS, fabricated using the Laser Powder Bed Fusion (L-PBF) method, exhibited a yield strength of 712 MPa and an elongation of 27.5%.…”