Stress state-dependent mechanics of additively manufactured 304L stainless steel: Part 1 – characterization and modeling of the effect of stress state and texture on microstructural evolution

The effect of stress state and crystallographic texture on strain-induced martensitic transformation kinetics in 304L stainless steel (SS304L) components made by additive manufacturing were investigated. Mechanical tests under uniaxial tension, uniaxial compression, and pure shear were performed. Experimental results showed that the rate of strain-induced martensitic phase transformation, with respect to plastic strain, was highest under uniaxial compression, followed by uniaxial tension, and lowest under pure shear. The higher rate of phase transformation under uniaxial compression than tension in the additively manufactured SS304L contradicts the trends often, but not always, observed in texture-free conventionally processed austenitic stainless steels. The combined effects of stress state, crystallographic texture, and chemistry were studied, for the first time, to develop a new strain-induced martensitic phase transformation kinetics equation for additively manufactured SS304L that captures the microstructural evolution as a function of plastic strain and these factors.