Journal
MATERIALS
Volume 15, Issue 19, Pages -Publisher
MDPI
DOI: 10.3390/ma15196824
Keywords
computational materials engineering; microalloyed steel; mechanics of materials; flow curve; dislocation density evolution
Categories
Funding
- Christian Doppler Forschungsgesellschaft
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In this study, a combination of materials modeling and experimental results was used to investigate the evolution of dislocation density in microalloyed steels. It was found that plastic stresses at high temperatures were independent of the precipitation state, and a single set of empirical equations was sufficient to model all investigated microalloyed steels.
Microalloyed steels offer a good combination of desirable mechanical properties by fine-tuning grain growth and recrystallization dynamics while keeping the carbon content low for good weldability. In this work, the dislocation density evolution during hot rolling was correlated by materials modeling with flow curves. Single-hit compression tests at different temperatures and strain rates were performed with varying isothermal holding times prior to deformation to achieve different precipitation stages. On the basis of these experimental results, the dislocation density evolution was evaluated using a recently developed semi-empirical state-parameter model implemented in the software MatCalc. The yield stress at the beginning of the deformation sigma(0), the initial strain hardening rate theta(0), and the saturation stress sigma(infinity)-as derived from the experimental flow curves and corresponding Kocks plots-were used for the calibration of the model. The applicability for industrial processing of many microalloyed steels was assured by calibration of the model parameters as a function of temperature and strain rate. As a result, it turned out that a single set of empirical equations was sufficient to model all investigated microalloyed steels since the plastic stresses at high temperatures did not depend on the precipitation state.
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