Abstract
A new constitutive model for Q235B structural steel is proposed, incorporating the effect of dynamic strain aging. Dynamic strain aging hugely affects the microstructural behavior of metallic compounds, in turn leading to significant alterations in their macroscopic mechanical response. Therefore, a constitutive model must incorporate the effect of dynamic strain aging to accurately predict thermo-mechanical deformation processes. The proposed model assumes the overall response of the material as a combination of three contributions: athermal, thermally activated, and dynamic strain aging stress components. The dynamic strain aging is approached by two alternative mathematical expressions: (i) model I: rate-independent model; (ii) model II: rate-dependent model. The proposed model is finally used to study the mechanical response of Q235B steel for a wide range of loading conditions, from quasi-static loading ( and ) to dynamic loading ( and ), and across a broad range of temperatures (). The results from this work highlight the importance of considering strain-rate dependences (model II) to provide reliable predictions under dynamic loading scenarios. In this regard, rate-independent approaches (model I) are rather limited to quasi-static loading.
Highlights
IntroductionFrom the macrosFcroopmic tphoeinmt aocfrovsiceowp,icdpynoianmt iocfsvtriaeiwn, adgyinngam(DicSAs
In fcc metallic crystalline structures, the thermally activated mechanism is controlled and dominated by the long-range interactions related to heterogeneous microstructural occurrence and evolution of dislocations, which suggests a strong dependence on plastic strain
The thermal yield stress in bcc metals is highly dependent on temperature and strain rate whereas hardening is hardly affected by either temperature or strain rate. These mechanisms will be reflected in the development of the proposed model
Summary
From the macrosFcroopmic tphoeinmt aocfrovsiceowp,icdpynoianmt iocfsvtriaeiwn, adgyinngam(DicSAs. GGeenneerraallllyy,, ffllooww ssttrreessss ddeecclliinneess aass tteemmppeerraattuurree rriisseess. The effect of strain rate on the DSA-induced. Two mathematical models will be introduced for the variables in the DSA component σD, and they will be referred to as ‘proposed model I (or PM I)’ and ‘proposed model II (or PM II)’ The VA model and PM I are expected to present some limitations to capture the DSA effect accurately.
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