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.

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.

Induction Hardening of a 0.40 % C Novel Microalloyed Steel: Effects of Heating Rate on the Prior Austenite Grain Size

2018 ◽  
Vol 941 ◽  
pp. 64-70
Author(s):  
Vahid Javaheri ◽  
Nasseh Khodaei ◽  
Tun Tun Nyo ◽  
David A. Porter
Keyword(s):  
Grain Size ◽  
Heating Rate ◽  
Prior Austenite ◽  
Induction Hardening ◽  
High Wear Resistance ◽  
Heating Rates ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Prior Austenite Grain Size ◽  
Prior Austenite Grain

This work explores the effect of heating rate on the prior austenite grain size and hardness of a thermomechanically processed novel niobium-microalloyed 0.40 % carbon low-alloyed steel intended for use in induction hardened slurry pipelines. The aim was to identify the heating rates that lead to the maximum hardness, for high wear resistance, and minimum prior austenite grain size, for high toughness. For this purpose, a Gleeble 3800 machine has been employed to simulate the induction hardening process and provide dilatometric phase transformation data. The prior austenite grain structure has been reconstructed from the EBSD results using a MatlabR script supplemented with MTEX texture and crystallography analyses. Heating rates ranged from 1 to 50 °C/s and the cooling rate was 50 °C/s. The results show that the prior austenite grain size greatly depended on the heating rate: compared to the lower heating rates, the maximum heating rate of 50 C/s produces remarkably fine prior austenite grains and a fine final martensitic microstructure after quenching. In addition, a relation between the heating rate and the deviation from equilibrium temperature has been established.

scholarly journals Influence of Austenite Grain Size on Mechanical Properties after Quench and Partitioning Treatment of a 42SiCr Steel

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 577 ◽  
Author(s):  
Sebastian Härtel ◽  
Birgit Awiszus ◽  
Marcel Graf ◽  
Alexander Nitsche ◽  
Marcus Böhme ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Heating Rates ◽  
Austenite Grain Size ◽  
Grain Sizes ◽  
Austenite Grain ◽  
Martensitic Microstructure ◽  
Pre Treatment ◽  
Uneven Heating ◽  
Upsetting Test

This paper examines how the initial austenite grain size in quench and partitioning (Q-P) processes influences the final mechanical properties of Q-P steels. Differences in austenite grain size distribution may result, for example, from uneven heating rates of semi-finished products prior to a forging process. In order to quantify this influence, a carefully defined heat treatment of a cylindrical specimen made of the Q-P-capable 42SiCr steel was performed in a dilatometer. Different austenite grain sizes were adjusted by a pre-treatment before the actual Q-P process. The resulting mechanical properties were determined using the upsetting test and the corresponding microstructures were analyzed by scanning electron microscopy (SEM). These investigations show that a larger austenite grain size prior to Q-P processing leads to a slightly lower strength as well as to a coarser martensitic microstructure in the Q-P-treated material.

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.

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.

The Effect of Austenite Grain Size on the Growth of Different Ferrite Morphologies in a Nb-Microalloyed Steel

2009 ◽  
Vol 289-292 ◽  
pp. 109-117 ◽  
Author(s):  
Mohamad Esmailian
Keyword(s):  
Growth Rate ◽  
Grain Size ◽  
Grain Boundary ◽  
Microalloyed Steels ◽  
Growth Behaviour ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Intragranular Ferrite ◽  
Austenite Grains ◽  
Grain Boundary Ferrite

The effect of austenite grain size on the austenite to ferrite transformation temperature and different ferrite morphologies and growth behaviour in one Nb-microalloyed (HSLA) steel has been investigated. Three different austenite grain sizes were selected and cooled for obtaining austenite to ferrite and growth behaviour of ferrite. Moreover, samples with specific austenite grain size have been quenched, partially, for investigation of the microstructural evolution. The optical microscopy observation suggested that the nucleation site of ferrite is on edge and inside of austenite grains in Nb- microalloyed steels. Micrographs of different ferrite morphologies show that at high temperatures, where diffusion rates are higher, grain boundary ferrite nucleates both at the edge and corner of austenite grains and grows into both austenite grains. As the temperature is lowered and the driving force for ferrite formation increases, intragranular sites inside the austenite grains become operative as nucleation sites and suppress the grain boundary ferrite growth. With more undercooling,intragranular ferrites are seen to nucleate and grow more extensively , indicating the beginning of displacive transformation. Furthermore, growth rate of intragranular ferrite shows that by increasing of austenite grain size, the growth rate of intragranular ferrite increases extensively and growth rate of grain boundary ferrite decreases. The growth kinetics of grain boundary ferrite shows that this transformation is controlled by the diffusion of carbon in the austenite ahead of the interface.

scholarly journals Metallographic techniques for the determination of the austenite grain size in medium-carbon microalloyed steels

2001 ◽  
Vol 46 (5) ◽  
pp. 389-398 ◽  
Author(s):  
C Garcı́a de Andrés ◽  
M.J Bartolomé ◽  
C Capdevila ◽  
D San Martı́n ◽  
F.G Caballero ◽  
...  
Keyword(s):  
Grain Size ◽  
Microalloyed Steels ◽  
Austenite Grain Size ◽  
Medium Carbon ◽  
Austenite Grain ◽  
Carbon Microalloyed
Sign in / Sign up

Export Citation Format

Share Document