Multiscale Analysis of Processing-Microstructure-Mechanical Behavior Interrelationships of UFG Microalloyed Steels

• Published in: Steel research international Vol. 85; no. 6; pp. 1128 - 1141
• Main Authors: Muszka, Krzysztof, Majta, Janusz
• Format: Journal Article
• Language: English
• Published: Weinheim Blackwell Publishing Ltd 01.06.2014; Wiley Subscription Services, Inc
• Subjects: Construction; Crystallography; Deformation; Dislocations; Hardening; High strength low alloy steels; Materials science; Microstructure; Steel alloys; Structural materials; Structural steels
• ISSN: 1611-3683; 1869-344X
• DOI: 10.1002/srin.201300178

The processing difficulties and enhanced ductility of UFG (ultrafine‐grained) microalloyed steels are currently one of the most stimulating challenges due to problems in practical applications as structural materials. A key challenge is the ability to represent the real behavior of such modern structural material using multiscale approach. In this study, various processing routes and nonlinear combined hardening model were applied to capture strain path effects that play major role in the deformation process of UFG microalloyed steels. Special emphases are given on the inhomogeneity of the accumulated energy of deformation and resulted microstructure evolution. The hardening model was implemented into a multiscale constitutive model within a crystal plasticity framework. The proposed idea provides a bridge between the dislocation substructure and fine precipitates interactions at the nano‐ and microscale, local stress concentrations on the grain boundaries at the microscale, intragranular stresses at the mesoscale, and material mechanical response at the macroscale. Based on experimental results, in order to fully cover all the analysis scales, the multiscale modeling approach is proposed. The results presented in this study show that a combination of continuum mechanics and dislocation theory can be used successfully to map dislocation strengthening and to build a rheological model for UFG microalloyed steels. This paper discusses the interrelationships between processing parameters, microstructure, and mechanical behavior of microalloyed ultrafine‐grained steels. Grain refinement possibilities of microalloyed steels using Advanced Thermomechanical Processing and Severe Plastic Deformation routes were studied. Based on that, in the second part of the work, the recent work on multiscale modeling has been revised in the light of its potential application to simulation of chosen SPD processes.