scholarly journals The Role of Elements Partition and Austenite Grain Size in the Ferrite-Bainite Banding Formation during Hot Rolling

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2356
Author(s):  
Yina Zhao ◽  
Yinli Chen ◽  
He Wei ◽  
Jiquan Sun ◽  
Wei Yu
Keyword(s):  
Grain Size ◽  
Hot Rolling ◽  
Heating Temperature ◽  
Rolling Process ◽  
Heating Time ◽  
Cast Slab ◽  
Austenite Grain Size ◽  
Hot Rolling Process ◽  
Austenite Grain ◽  
And Diffusion

The partitioning and diffusion of solute elements in hot rolling and the effect of the partitioning and diffusion on the ferrite-bainite banding formation after hot rolling in the 20CrMnTi steel were experimentally examined by EPMA (electron probe microanalysis) technology and simulated by DICTRTA and MATLAB software. The austenite grain size related to the hot rolling process and the effect of austenite grain size on the ferrite-bainite banding formation were studied. The results show that experimental steel without banding has the most uniform hardness distribution, which is taken from the edge of the cast slab and 1/4 diameter position of the cast slab, heating at 1100 °C for 2 h and above 1200 °C for 2–4 h during the hot rolling, respectively. Cr, Mn, and Si diffuse and inhomogeneously concentrate in austenite during hot rolling, while C homogeneously concentrates in austenite. After the same hot rolling process, ΔAe3 increases and ferrite-bainite banding intensifies with increasing initial segregation width and segregation coefficient K of solute elements. Under the same initial segregation of solute elements, ΔAe3 drops and ferrite-bainite banding reduces with increasing heating temperature and extension heating time. When ΔAe3 drops below 14 °C, ferrite-bainite banding even disappears. What is more, the austenite grain size increases with increasing heating temperature and extension heating time. When the austenite grain size is above 21 μm, the experimental steel will not appear to have a banded structure after hot rolling.

Numerical Simulation of Microstructure Evolution during Continuous Hot Rolling Process of GCr15 Steel Rod

2021 ◽  
Vol 1016 ◽  
pp. 1733-1738
Author(s):  
Li Wen Zhang ◽  
Fei Li ◽  
Chi Zhang ◽  
Pei Gang Mao ◽  
Chao Qun Li
Keyword(s):  
Grain Size ◽  
Finite Element ◽  
Microstructure Evolution ◽  
Hot Rolling ◽  
Rolling Process ◽  
Equivalent Strain ◽  
Austenite Grain Size ◽  
Gcr15 Steel ◽  
Hot Rolling Process ◽  
Austenite Grain

In this paper, the microstructure evolution during continuous hot rolling process of GCr15 steel rod was investigated. A series of multi-field coupled finite element models were established based on commercial finite element software MSC.Marc. The kinetics equations of austenite grain size evolution of GCr15 steel were coupled to these models by a designed MSC.Marc subprogram. The field variables, including temperature, equivalent stress, equivalent strain, and equivalent strain rate, were calculated. The distributions of dynamic recrystallization, metadynamic recrystallization, and static recrystallization fractions were investigated. The distribution and evolution of austenite grain size at different stages in the continuous hot rolling process were analyzed. To verify the models, the temperatures of GCr15 steel rod at different stages in the continuous hot rolling process were measured. And the austenite grain sizes at cross section of the rod after the continuous hot rolling process were measured. The simulation results show a good agreement with the experimental results.

Numerical Simulation of Rolling Process and Microstructure Evolution of AM50 Mg Alloy during Hot Rolling Process

2011 ◽  
Vol 291-294 ◽  
pp. 449-454 ◽  
Author(s):  
Fuan Hua ◽  
Chao Yi Zhang ◽  
Qiang Li ◽  
Bao Yi Yu ◽  
Wei Hua Liu ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Grain Size ◽  
Microstructure Evolution ◽  
Hot Rolling ◽  
Heating Temperature ◽  
Simulation Method ◽  
Rolling Process ◽  
Mg Alloy ◽  
Hot Rolling Process ◽  
Rolling Method

In order to optimize rolling process of AM50 Mg alloy, numerical simulation method is adopted to find reasonable process parameters. And then, the metallograph was viewed to find the microstructure evolution during hot rolling process. Through numerical simulation it is found that while the heating temperature is 420 and the train less than 0.33 each time. Through 10 times rolling, a 10mm thickness plate was rolled to 0.5mm, and its grain size also decreases to 10μm, which indicates that AM50 Mg alloy can be formed by hot rolling method.

scholarly journals Austenite Grain Growth Kinetics in API X65 and X70 Line-Pipe Steels during Isothermal Heating

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Asiful Hossain Seikh ◽  
Mahmoud S. Soliman ◽  
Abdulhakim AlMajid ◽  
Khaled Alhajeri ◽  
Waleed Alshalfan
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Heating Temperature ◽  
Heating Time ◽  
Austenite Grain Size ◽  
Line Pipe ◽  
Austenite Grain ◽  
Steel Grades ◽  
Grain Growth Kinetics ◽  
Reheating Process

The aim of the present work is to investigate the microstructural behavior of austenite grain size (AGS) during the reheating process of two different API steel grades (X65 and X70). The steel samples were austenitized at 1150°C, 1200°C, and 1250°C for various holding times from 10 to 60 minutes and quenched in ice water. The samples were then annealed at 500°C for 24 hours to reveal the prior AGS using optical microscopy. It was noticed that the AGS in X65 grade is coarser than that of X70 grade. Additionally, the grain size increases with increasing the reheating temperature and time for both steels. The kinetics of grain growth was studied using the equationdn-d0n=Atexp-Q/RT, wheredis the measured grain size,dois the initial grain size,nis the grain size exponent,tis the heating time,Tis the heating temperature,Qis the activation energy,Ris the gas constant, andAis a constant. To characterize the grain growth process the values ofn,Q, andAwere determined. Good agreement is obtained between the prediction of the model and the experimental grain size values.

Austenite Grain Evolution Mechanism of High Carbon Rail Based on Thermal Technology

2020 ◽  
Vol 837 ◽  
pp. 74-80
Author(s):  
Jun Yuan ◽  
Zhen Yu Han ◽  
Yong Deng ◽  
Da Wei Yang
Keyword(s):  
Grain Size ◽  
Tensile Strength ◽  
Rail Steel ◽  
Heating Temperature ◽  
Great Influence ◽  
Stable Operation ◽  
High Carbon ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Austenite Grains

In view of the special requirements of rails to ensure the safe and stable operation of Railways in China, the formation characteristics of austenite grains in high carbon rail are revealed through industrial exploration, the process of industrial rail heating and rolling is simulated, innovative experimental research methods such as different heating and heat treatment are carried out on the actual rails in the laboratory. Transfer characteristics of austenite grain size, microstructures and key properties of high carbon rail during the process are also revealed. The results show that the austenite grain size of industrial produced U75V rail is about 9.0 grade. When the holding temperature is increased from 800 C to 1300 C, the austenite grain size of high carbon rail steel decreases, the austenite grain are gradually coarsened, and the tensile strength increases slightly. The tensile strength is affected by the heating temperature. With the increase of heating temperature, the elongation and impact toughness of high carbon rail decrease. The heating temperature of high carbon rail combined with austenite grain size shows that the heating temperature has a great influence on austenite grain size, and has the most obvious influence on the toughness of high carbon rail.

Austenite Grain Structures in Ti and Nb-Containing HSLA Steel during Slab Reheating

2014 ◽  
Vol 783-786 ◽  
pp. 669-673
Author(s):  
Debalay Chakrabarti ◽  
S. Roy ◽  
Dinesh Srivastava ◽  
Gautam Kumar Dey
Keyword(s):  
Grain Size ◽  
Hsla Steel ◽  
Size Variation ◽  
Inhomogeneous Distribution ◽  
Low Carbon ◽  
Cast Slab ◽  
Austenite Grain Size ◽  
Intermediate Temperature Range ◽  
Austenite Grain ◽  
Grain Structures

Spatial distribution of microalloy precipitates have been characterized in a low carbon microalloyed steel containing Nb, Ti and V. Micro-segregation during casting resulted in an inhomogeneous distribution of Nb (and also Ti) precipitates in the as-cast slab. Austenite grain growth has been investigated in the above mentioned steel, using different reheating temperatures between 1000°C and 1250°C for 1 h. Inhomogeneous distribution of Nb-rich precipitates created austenite grain size bimodality after reheating to an intermediate temperature range (1150-1200°C). Uniformly fine and uniformly coarse grain structures were found after reheating at lower- (≤ 1075°C) and higher-reheating temperatures (≥ 1250°C). A model has been proposed for the prediction of austenite grain size variation in the reheated steel.

The Influence of Initial Grain Size and Strain Sequence of Slab Hot Rolling on the Austenite Evolution of Peritectic Microalloyed Plate Steels

2014 ◽  
Vol 1019 ◽  
pp. 339-346 ◽  
Author(s):  
Rorisang Maubane ◽  
Kevin Banks ◽  
Waldo Stumpf ◽  
Charles Siyasiya ◽  
Alison Tuling
Keyword(s):  
Grain Size ◽  
Hot Rolling ◽  
Plain Carbon Steel ◽  
Microalloyed Steels ◽  
Heating Rates ◽  
Austenite Grain Size ◽  
Soaking Time ◽  
Austenite Grain ◽  
Dynamic Recrystallisation ◽  
Temperature Constant

The influence of the strain sequence during slab hot rolling (also known as “roughing”) on the evolution of austenite in plain carbon, C-Mn-V and C-Mn-Nb-Ti-V steels was investigated. Reheating and roughing simulations were conducted in a Bähr deformation dilatometer using a constant austenitising temperature, constant soaking time and various heating rates and roughing strain sequences. Stress analysis was used to quantify the austenite softening behaviour and the prior austenite grain size was measured from quenched specimens. The austenite grains of the plain carbon steel were coarser than those of both microalloyed steels, with the C-Mn-Nb-Ti-V grade being the finest due to effective pinning of the grain boundaries. Pass strains greater than 0.2 were sufficient for initiation of dynamic recrystallisation (DRX) for the C-Mn and C-Mn-V steels and led to uniform austenite microstructure with austenite grain sizes less than 40µm after the roughing stage.

Investigation of the Austenite Grain Growth in HY-TUF Steel

2020 ◽  
Vol 299 ◽  
pp. 482-486
Author(s):  
Mikhail V. Maisuradze ◽  
Maksim A. Ryzhkov
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Heating Temperature ◽  
High Strength ◽  
Silicon Steel ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Austenite Grains ◽  
Austenite Grain Growth ◽  
Intensive Growth

The high strength silicon steel HY-TUF, applied for manufacturing of the heavy loaded aerospace and engineering parts, was investigated. The effect of the heating temperature in the range 900...1000 °C on the austenite grain size was studied. The steel under consideration had a significant scatter of the austenite grain size. The most intensive growth of the austenite grains was observed in the temperature range 975...1000 °C.

Microstructure Modeling of the Ribbed Steel Bar Hot Rolling of V-Microalloyed Steel

2010 ◽  
Vol 168-170 ◽  
pp. 599-602
Author(s):  
Lei Yang ◽  
Yi Zhu He ◽  
Xiao Min Yuan
Keyword(s):  
Grain Size ◽  
Hot Rolling ◽  
Integrated Model ◽  
Analytical Models ◽  
Austenite Grain Size ◽  
Microstructure Modeling ◽  
Austenite Grain ◽  
Steel Bar ◽  
Rod Rolling ◽  
Strain Model

This paper proposes an integrated model for the prediction of the pass-by-pass evolution of the austenite grain size of the ribbed steel bar hot rolling. The integrated model consists of a strain model, a temperature model, a microstructure evolution model of austenite grain size and a flow stress model. Hot rod rolling experiments are conducted to examine the proposed analytical models. The integrated model is employed to examine the effects of modifications of the refined austenite grain size of the 500MPa ribbed steel bar. Refinement of ferrite could be realized by refining the austenite grain size at the final pass.

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