Combining Gleeble thermomechanical simulations and finite element analysis to replicate the material state of additively manufactured duplex stainless steels

Duplex stainless steels (DSS) are increasingly being investigated for use in additive manufacturing applications. The understanding of their processing-microstructure-property relationships is an integral part of their future development and application. This study involves physical and computational simulations of heat treatment conditions intended to mimic the complex thermal histories seen in additive manufacturing using a Gleeble thermal-mechanical simulator. The experimental simulations are performed on standard tensile specimens to obtain both bulk uniaxial tension and local microhardness. The ultimate tensile strength increased by ∼20 MPa from a single-cycle to a multi-cycle heat treatment for the DSS alloys 2101 and 2205. The δ-ferrite phase fraction for DSS 2101 increased by 2.1 % from the single-cycle to the multi-cycle heat treatment, while the δ-ferrite phase fraction for DSS 2205 decreased by 10.6 %. The average hardness from the center of the specimen to 6 mm from the center for both heat treatments of 2101 and 2205 was 225.0 ± 6.9 and 244.5 ± 4.5 HV 0.5 , respectively to show the gradient in temperature inherent to local Joule heating from the Gleeble simulator. Thermal histories simulated using finite element analysis have been correlated with local microstructures, from the Gleeble experiment samples and used to understand local properties, to determine the microstructural features that dictate the mechanical properties of the material. Both the phase fraction and the phase boundary volumetric area density have been found to be important microstructural features that influence the mechanical properties. An increase in both the ferrite phase fraction and phase boundary area density led to increases in microhardness.