Mechanical properties of nitrogen-containing austenitic steel obtained by multilayer arc deposition of a flux-cored wire

Austenitic stainless steels are characterized by paramagnetic properties, good ductility, toughness and corrosion resistance. However, their strength properties are relatively low. Nitrogen alloying is an effective way to increase their strength. The increased nitrogen and manganese content in steels of this class makes it possible to reduce the nickel content. The presence of delta ferrite in the structure of austenitic steels can improve their resistance to the formation of hot cracks. Wire arc additive manufacturing is a modern method of producing parts from austenitic steels. The authors have developed a flux-cored wire for wire arc additive manufacturing, which makes it possible to deposit metal containing nitrogen in chemical composition, high chromium and manganese content, low nickel content, and providing a structure of austenite and a small amount of δ-ferrite. The aim of the work was to certify the deposited material, including t he determination of structural features, micromechanical characteristics, and mechanical properties under conditions of static tensile loading and cyclic loading in the low cycle fatigue testing. As a result of multilayer depositing, deposited layers were obtained with a composition (by wt. %): <0.1 C; 21.1 Cr; 3.3 Ni; 5.0 Mn; 2.0 Mo; 2.8 Cu; 0.239 N. According to the results of X-ray and EBSD analyses, the structure of the deposited layers consists of austenite and 6 wt. % δ-ferrite. The properties of the studied material are compared with those of the widely used austenitic stainless steel AISI 321. Higher strength properties of the studied material are shown both during instrumental microindentation (HM=2.7 GPa; HIT=3.1 GPa) and static tensile testing (σ0,2=595 MPa; σВ=790 MPa; δ=28 %). The transition to multi-cycle fatigue of the developed material occurs at a stress amplitude within 550 MPa.