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Gu S.-D.,Dalian University of Technology | Zhang L.-W.,Dalian University of Technology | Yue C.-X.,Dalian University of Technology | Ruan J.-H.,Dalian University of Technology | And 2 more authors.
Computational Materials Science | Year: 2011

In this paper, based on finite element (FE) software MSC.Marc, a multi-field coupled FE model is established to investigate the 18-pass hot rolling process of GCr15 steel rod. Thermal, mechanical and microstructural phenomena during the rolling process are coupled in the model. In this model, the microstructure evolution of GCr15 Steel is described by some empirical equations which are obtained using the Gleeble-3800 thermomechanical simulator, and a MSC.Marc subprogram is designed to predict the evolution of recrystallization behavior and austenite grain size. With the aid of the model, the paper analyzes detailedly the distribution and evolution of microscopic field-variables in rolled piece during the whole rolling process of GCr15 steel rod. Predicted values of grain size show good agreement with measured ones. The current model is beneficial to understand the effect of recrystallization behavior and control the microstructure evolution during hot rod rolling process. © 2011 Elsevier B.V. All rights reserved. Source


Yang L.,University of Science and Technology Beijing | Cheng G.-G.,University of Science and Technology Beijing | Li S.-J.,University of Science and Technology Beijing | Zhao M.,Dongbei Special Steel Group | Feng G.-P.,Dongbei Special Steel Group
ISIJ International | Year: 2015

MgAl2O4-TiN complex inclusion found in GCr15SiMn ESR ingot with MgAl2O4 as the core and TiN as the periphery is of great harm to steel. The characteristics of this complex inclusion precipitation and growth during solidification of metal molten pool have been theoretically investigated with the help of thermodynamics and kinetics. The results demonstrate that during solidification of metal molten pool, TiN will precipitate on the existed core MgAl2O4 due to the microsegregation of solutes Ti and N. The effect of high cooling rate on the size of complex inclusion with the core MgAl2O4 from the consumable electrode is not significant, particularly for larger size of the core, while with the core MgAl2O4 formed during solidification, its size is greatly affected by the cooling rate, which will possibly provide a useful method of distinguishing the source of the core MgAl2O4 under high cooling rate. At the same cooling rate, the growing extent of periphery TiN decreases with the increasing size of the core MgAl2O4. Meanwhile, decreasing C content in steel within the upper and lower limit will decrease the percentage of this complex inclusion. © 2015 ISIJ. Source


Yue C.,Dalian University of Technology | Zhang L.,Dalian University of Technology | Liao S.,Dalian University of Technology | Gao H.,Dongbei Special Steel Group
Journal of Materials Engineering and Performance | Year: 2010

The growth behavior of austenite grains in GCr15 steel was investigated through the isothermal annealing tests of the steel under different heating temperatures and holding times. The tests were performed on a Gleeble-3800 thermo-mechanical simulation machine. Austenitizing temperatures 1223, 1323, 1373, and 1423 K were chosen, and holding time varied from 0 to 480 s. Experimental results suggest that austenite grains grow gradually with the increase of heating temperature, and holding time has an important effect on the growth of austenite grains. The time exponent for the growth is bigger at higher temperature, and the growth rate decreases with increasing time. On the basis of previous models and experimental results, a mathematical model that can describe the growth behavior of austenite grains in the tested steel under different heating temperatures and holding times was obtained using regression analysis. The predicted grain sizes by the model are in good agreement with measured ones. © 2009 ASM International. Source


Yang L.,University of Science and Technology Beijing | Cheng G.-G.,University of Science and Technology Beijing | Li S.-J.,University of Science and Technology Beijing | Zhao M.,Dongbei Special Steel Group | Feng G.-P.,Dongbei Special Steel Group
ISIJ International | Year: 2015

TiN inclusion with large size found in ESR ingot is of great harm to steel GCr15SiMn, it is significant to elucidate the possibility of this inclusion in consumable electrode retaining in the subsequent ingot and the effect of slag composition on the content of TiN inclusion in ingot after ESR refining. Based on three remeltings and with the help of ultrahigh-temperature confocal scanning violet laser microscope, it demonstrates that TiN inclusion in electrode will completely decompose in the solid-liquid coexistence region at the electrode tip, reflecting that TiN inclusion found in ESR ingot is regenerated. For different contents of Ti in slag, there is a corresponding equilibrium value of Ti content in steel, when the content of Ti in electrode is higher than this critical equilibrium value, it will decline in steel, otherwise Ti pick-up will occur. The effect of increasing SiO2 content in slag on decreasing Ti content in steel is obvious due to the Si/Ti exchange reaction taking place, further leading to the low content of TiN in ingot. © 2015 ISIJ. Source


Zhu D.,University of Science and Technology Beijing | Liu G.,University of Science and Technology Beijing | Li M.,University of Science and Technology Beijing | Zhang S.,University of Science and Technology Beijing | And 10 more authors.
Physics Procedia | Year: 2013

This article describes a production method of mould steel pre-hardening, and focus on the advantage of this method, The technical core of method is the variable frequency and variable amplitude pulse uniform high-precision temperature control, which achieved by using strong-medium-weak water cooling, gas-water cooling and gas mist cooling composite cooling control technology. Optimizing the cooling rate path is a good method of optimizing quenched organization and structure. © 2013 The Authors. Published by Elsevier B.V. Source

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