Evolution of Austenite Grain Size in Continuously Cast Slab during Hot-Core Heavy Reduction Rolling Process Based on Hot Compression Tests

2018 ◽  
Vol 89 (7) ◽  
pp. 1800025 ◽  
Author(s):  
Meina Gong ◽  
Haijun Li ◽  
Tianxiang Li ◽  
Bin Wang ◽  
Zhaodong Wang
Keyword(s):  
Grain Size ◽  
Rolling Process ◽  
Hot Compression ◽  
Compression Tests ◽  
Cast Slab ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Continuously Cast

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.

scholarly journals Study of Static Recrystallization Kinetics and the Evolution of Austenite Grain Size by Dynamic Recrystallization Refinement of an Eutectoid Steel

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1289
Author(s):  
Cesar Facusseh ◽  
Armando Salinas ◽  
Alfredo Flores ◽  
Gerardo Altamirano
Keyword(s):  
Grain Size ◽  
Dynamic Recrystallization ◽  
Static Recrystallization ◽  
Controlled Rolling ◽  
Strain Rates ◽  
Peak Strain ◽  
Compression Tests ◽  
Eutectoid Steel ◽  
Austenite Grain Size ◽  
Austenite Grain

Interrupted and continuous hot compression tests were performed for eutectoid steel over the temperature range of 850 to 1050 °C and while using strain rates of 0.001, 0.01, 0.1, and 1 s−1. The interrupted tests were carried out to characterize the kinetics of static recrystallization(SRX) and determinate the interpass time conditions that are required for initiation and propagation of dynamic recrystallization (DRX), while considering that the material does not contain microalloying elements additions for the recrystallization delay. Continuous testing was used to investigate the evolution of the austenite grain size that results from DRX. The results indicate that carbon content accelerates the SRX rate. This effect was observed when the retardation of recrystallization due to a decrease in deformation temperature from 1050 to 850 °C was only about one order of magnitude. The expected decelerate effect on the SRX rate when the initial grain size increases from 86 to 387 µm was not significant for this material. Although the strain parameter has a strong influence on SRX rate, in contrast to a lesser degree of strain rate, both of the effects are nearly independent of the chemical composition. The calculated maximum interpass times that are compatible with DRCR (Dynamic Recrystallization Controlled Rolling), for relatively low strain rates, suggest that the onset and maintaining of the DRX is possible. However, while using the empirical equations that were developed in the present work to estimate the maximum times for high strain rates, such as those observed in the wire and rod mills, indicate that the DRX start is feasible, but maintaining this mechanism for 5% softening in each pass after peak strain is not possible.

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.

Development and Industrial Applying on Rolling Mill 5000 of the Model of Austenite Grain Size Evolution in Nb-Microalloyed Steels

2016 ◽  
Vol 879 ◽  
pp. 312-317
Author(s):  
A.V. Chastukhin ◽  
D.A. Ringinen ◽  
S.V. Golovin ◽  
L.I. Efron
Keyword(s):  
Grain Size ◽  
Rolling Mill ◽  
Microalloyed Steels ◽  
Compression Tests ◽  
Austenite Grain Size ◽  
Soaking Time ◽  
Austenite Grain ◽  
Size Evolution ◽  
South Stream ◽  
Rolled Plates

In this research evolution of austenite grain size in Nb-microalloyed steels X65÷X120 grades during slab reheating and roughing rolling was studied. A mathematical model has been development to obtain the target temperature and soaking time in furnace, which ensure a uniform austenite structure and maximum possible dissolution of the carbonitride particles prior to roughing rolling. The Hot Rolling Recrystallization Model (HRRM) has also development to predict the austenite microstructure evolution during roughing rolling. The model is based on empirical equations and organized following a tree-structure. A validation of the model has been carried out in the laboratory by multipass compression tests. The models jointly have been used to create new strategies of processing technology of rolled plates on rolling mill 5000 for the South Stream pipeline. The industrial application has confirmed a great benefit of the models in point of cold resistance of rolled plates.

A Model for Predicting the Austenite Grain Size at the Surface of Continuously-Cast Slabs

2008 ◽  
Vol 39 (6) ◽  
pp. 885-895 ◽  
Author(s):  
Christian Bernhard ◽  
Jürgen Reiter ◽  
Hubert Presslinger
Keyword(s):  
Grain Size ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Continuously Cast

Recrystallization Behavior of 0.11% Ti-Added Complex Phase Steel during Hot Compression

2013 ◽  
Vol 762 ◽  
pp. 128-133 ◽  
Author(s):  
Mei Zhang ◽  
Chao Bin Huang ◽  
Wei Ming Zeng ◽  
Ren Yu Fu ◽  
Lin Li
Keyword(s):  
Grain Size ◽  
Microstructure Evolution ◽  
Kinetic Method ◽  
Hot Compression ◽  
Recrystallization Temperature ◽  
Recrystallization Process ◽  
Recrystallization Behavior ◽  
Compression Tests ◽  
Complex Phase ◽  
Austenite Grain

Double-hit isothermal deformation and multi-pass continuous cooling hot compression tests were carried out to study the recrystallization behavior of a 0.11 (in mass %) Ti-microalloyed complex phase (CP) steel. The influence of different deforming temperatures and holding times on microstructure evolution was investigated. The results showed that a pronounced austenite grain refinement after appropriate recrystallization process has been detected. The grain size decreases continuously from 176μm to 20μm after four-pass compression. It has been verified that non-crystallization temperature (Tnr) of the experimental steel is about 975°C under the deformation conditions. Based on the stress-strain curves, a kinetic method was established to predict the non-recrystallization temperature of the studied steel during nonisothermal continuous hot deformation.

Transverse Surface Cracks in Continuously Cast Steel Slabs, Oscillation Marks and Austenite Grain Size

2010 ◽  
Vol 638-642 ◽  
pp. 3603-3609 ◽  
Author(s):  
Rian Dippenaar
Keyword(s):  
Grain Size ◽  
Low Carbon Steel ◽  
Surface Cracks ◽  
Low Carbon ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Continuously Cast ◽  
Steel Slabs ◽  
Ferrite Films ◽  
Oscillation Marks

Transverse surface cracks in low carbon steel slabs are invariably inter-granular and follow the soft ferrite films outlining the grain boundaries of exceptionally large prior-austenite grains often found at the roots of oscillation marks in continuously cast low-carbon steel slabs. Plastic deformation is concentrated in the ferrite films and cracks initiate in the ferrite films, leading to crack propagation along the austenite grain boundaries. Hot-ductility is significantly reduced by an increase in austenite grain size and in situ observations revealed that depending on the cooling rate, austenite can nucleate and grow by diffusional mechanisms or forms by a massive type of reaction. The delta-ferrite transformation has also been studied by using neutron diffraction techniques and high-energy X-rays in a synchrotron.

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