Stress-strain models of austenitic stainless steels produced by advanced 3D printing methods

Abstract

Wire arc additive manufacturing (WAAM) and selective laser melting (SLM) are two advanced three-dimensional (3D) printing manufacturing methods. This paper presents the proposal of the constitutive stress-strain models of austenitic stainless steels produced by advanced WAAM and SLM printing methods. The existing tensile coupon tests of WAAM and SLM austenitic stainless steels were first collected, including a total of 301 WAAM specimens and 85 SLM specimens. It should be noted that the quality of the 3D printed specimens highly relies on the well settings of the critical printing parameters. Therefore, the effects of the critical printing parameters such as specimen test orientation, thickness, welding voltage, welding current, wire feeding rate, layer thickness and inter-layer temperature of WAAM as well as scanning speed, energy density and laser power of SLM on the material properties were then analyzed. Finally, three constitutive stress-strain models are proposed for the machined WAAM, as-built WAAM and SLM austenitic stainless steels, respectively. The proposed stress-strain models only require two basic parameters of 0.2% proof stress and elastic modulus as inputs. Other material parameters of ultimate strain, ultimate stress and strain hardening exponents needed in the proposed material models are determined by using the proposed predictive expressions which are also in terms of the elastic modulus and 0.2% proof stress. The proposed stress-strain models can fit well with test results, which can be used to predict their stress-strain behavior, and are also suitable in the future numerical analysis for the structural response of WAAM and SLM steels.