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Effect of Temperature and Strain Rate on the Hot Deformation Behaviour of Ferritic Stainless Steel
Guoqing Zu,Yukuan Lu,Yi Yan,Xiaoming Zhang,Jingwei Zhao,Wei Du,Xu Ran,Zhengyi Jiang 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.2
The fow behaviour and microstructure characteristics of a ferritic stainless steel were investigated using plain strain compression test on a Gleeble 3500 thermo-mechanical test simulator with a hydrawedge system in the temperature range of850–1100 °C and strain rate range of 0.1–50 s−1. The phenomenological constitutive model and the relationship betweenthe Zener–Hollomon (Z) parameter and fow stress were established. The results reveal that the fow softening phenomenonoccurs at high strain rate, which is caused by the coupling efect of the adiabatic heating and dynamic recrystallisation (DRX). New grains nucleate preferentially at the original grain boundaries by strain-induced grain boundary migration. With anincrease of temperature or strain rate, a part of new grains form in the interior of deformed grains. The DRX grain size andfraction increase with the increase of temperature, however, exhibit a non-linear relationship with strain rate.
Yufan Wang,Guoqing Zu,Di Zhang,Di Zhang,Weiwei Zhu,Huilan Sun,Bo Wang,Xu Ran 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.11
In the present work, the effect of pre-annealing on the recrystallized texture of hot-rolled Fe-1.6 wt% Si non-oriented electricalsteel was investigated. Vickers hardness test, optical microscope, and electron backscatter diffraction were used to investigatethe changes in the average hardness, microstructure, and texture caused by pre-annealing of hot-rolled strips. It was found thatthe texture successively changed from a near-random distribution to {116} < 151 > texture and near-{001} < 140 > texturedepending on pre-annealing treatments. Also, there was almost no effect on the grain size, and the average grain size of thenormalized bands was 125 μm. Besides, the texture and magnetic properties of the final products under different pre-annealingtreatments were also detected. It was found that the sample obtain a strong Cube texture by pre-annealing. Meanwhile, themagnetic properties are also got an improvement by pre-annealing. In a word, this method may provide a possibility to obtainan ideal grain size and texture simultaneously.
Flow Behaviour and Constitutive Modelling of a Ferritic Stainless Steel at Elevated Temperatures
Jingwei Zhao,Zhengyi Jiang,Guoqing Zu,Wei Du,Xin Zhang,Laizhu Jiang 대한금속·재료학회 2016 METALS AND MATERIALS International Vol.22 No.3
The flow behaviour of a ferritic stainless steel (FSS) was investigated by a Gleeble 3500 thermal-mechanical test simulator over the temperature range of 900-1100 °C and strain rate range of 1-50 s -1 . Empirical and phenomenological constitutive models were established, and a comparative study was made on the predictability of them. The results indicate that the flow stress decreases with increasing the temperature and decreasing the strain rate. High strain rate may cause a drop in flow stress after a peak value due to the adiabatic heating. The Zener-Hollomon parameter depends linearly on the flow stress, and decreases with raising the temperature and reducing the strain rate. Significant deviations occur in the prediction of flow stress by the Johnson-Cook (JC) model, indicating that the JC model cannot accurately track the flow behaviour of the FSS during hot deformation. Both the multiple-linear and the Arrhenius-type models can track the flow behaviour very well under the whole hot working conditions, and have much higher accuracy in predicting the flow behaviour than that of the JC model. The multiple-linear model is recommended in the current work due to its simpler structure and less time needed for solving the equations relative to the Arrhenius-type model.