Multiscale Modeling for Residual Stresses Analysis of a Cast Super Duplex Stainless Steel

Chemical, physical, thermal, and mechanical behavior of complex alloys, such as super-duplex stainless steels (SDSS), is largely dependent on the characteristics of its multiphase microstructure which is controlled by chemical composition and cooling rate in the temperature range of 1000 to 300 ℃. During solidification, a microstructure composed of ferrite, austenite, and non-ideal phases can be formed, introducing residual stresses due to the different coefficient of thermal expansion and elastoplastic properties of the phases. Since residual stresses may have a significant impact on components, causing distortion and early failure, it is critical to understand their origin (at the microscale) and effect (at the macroscale). Multiscale material modeling provides an opportunity to analyze the material in different scales, leading to the optimization of material design and behavior. This work addresses the effect of distribution and volume fraction of phases on the magnitude and gradient of residual stresses on a cast SDSS specimen. The numerical method for the homogenization of the material properties is also addressed. The procedure followed consisted of modeling the microstructure by assigning phases properties to the features in optical micrographs and generating a finite element mesh to compute the macroscopic material properties. The software OOF was used to model the microstructures and ABAQUSTM/CAE was applied to simulate the cooling of the specimen and to analyze the residual stresses.