Mesoscopic Simulation of the Ferrite Nucleation on Austenitic Grain Boundary for Nanograined Steel

2015 ◽  
Vol 817 ◽  
pp. 731-735
Author(s):  
Peng Yu ◽  
Lin Zhang ◽  
Lin Xiu Du ◽  
Jun Hu
Keyword(s):  
Grain Size ◽  
Phase Transformation ◽  
Nucleation Process ◽  
Austenite Grain Size ◽  
Mesoscopic Simulation ◽  
Thermodynamics And Kinetics ◽  
Austenite Grain ◽  
Austenite Grains ◽  
Ferrite Nucleation ◽  
Kinetics Of

We use the cellular automaton (CA) modeling to investigate the ferrite nucleation on the austenite grains. On the basis of the thermodynamics and kinetics of phase transformation from austenite to ferrite, the CA modeling demonstrates that the size of nucleated ferrite grains is increased with increasing of cooling rates, and nucleation process is finished instantly at a given cooling rate. The initial austenite grain size plays an important role in the obtained ferrite nucleation number, and the potential nucleation cells are increased.

Nanocrystallization of Bulk Steels through γ/α Transformation

2007 ◽  
Vol 539-543 ◽  
pp. 4687-4691
Author(s):  
Lin Xiu Du ◽  
Ming Xian Xiong ◽  
Xiang Hua Liu ◽  
Guo Dong Wang
Keyword(s):  
Grain Size ◽  
Phase Transformation ◽  
Microalloyed Steel ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Austenite Grains

A method of obtaining nanocrystallized bulk steels through phase transformation was investigated. Firstly, the austenite grain size of a microalloyed steel was refined to 1~3μm through repeatly heating and quenching; secondly, the samples with ultrafined austenite grains were heavily deformed at different temperature, and the uniform microstructures with some 0.1~0.3μm equiaxed ferrites were obtained.

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.

Effect of Austenitizing Temperature on the Quenching Microstructure and Properties of 51CrV4

2019 ◽  
Vol 944 ◽  
pp. 357-363
Author(s):  
Xiao Dong Zhang ◽  
Dian Xiu Xia ◽  
Shou Ren Wang
Keyword(s):  
Grain Size ◽  
Austenitizing Temperature ◽  
Austenite Grain Size ◽  
Microstructure And Properties ◽  
Austenite Grain ◽  
Test Steel ◽  
Austenite Grains ◽  
Martensite Structure

The effect of austenitizing temperature on the quenching microstructure and properties of 51CrV4 steel was studied. The results show that with the increase of austenitizing temperature, the austenite grains grow gradually. After quenching, the hardness increased first and then decreased, and the strength increased first and then decreased after tempering at 460°C. When the austenitizing temperature was 880°C, the austenite grains were fine and uniform, about 16μm, the martensite structure was dense, the strength and hardness reached maximum. When the austenitizing temperature was 910°C, the decarburization phenomenon was obvious, and the strength, hardness and plasticity of the test steel decreased obviously. When the austenitizing temperature exceeded 910°C, the austenite grains grow sharply and some grains were abnormally coarse. The austenite grain size reached 20μm and the microstructure was coarser at austenitizing temperature of 950°C. Therefore, in order to ensure uniform grain size and no decarburization under the premise of complete austenitization, the best austenitizing temperature of 51CrV4 steel for good properties is 880°C.

scholarly journals Exploring the Difference in Bainite Transformation with Varying the Prior Austenite Grain Size in Low Carbon Steel

Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 988 ◽  
Author(s):  
Liangyun Lan ◽  
Zhiyuan Chang ◽  
Penghui Fan
Keyword(s):  
Grain Size ◽  
Prior Austenite ◽  
Low Carbon Steel ◽  
Low Carbon ◽  
Bainite Transformation ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Austenite Grains ◽  
Prior Austenite Grain Size ◽  
Prior Austenite Grain

The simulation welding thermal cycle technique was employed to generate different sizes of prior austenite grains. Dilatometry tests, in situ laser scanning confocal microscopy, and transmission electron microscopy were used to investigate the role of prior austenite grain size on bainite transformation in low carbon steel. The bainite start transformation (Bs) temperature was reduced by fine austenite grains (lowered by about 30 °C under the experimental conditions). Through careful microstructural observation, it can be found that, besides the Hall–Petch strengthening effect, the carbon segregation at the fine austenite grain boundaries is probably another factor that decreases the Bs temperature as a result of the increase in interfacial energy of nucleation. At the early stage of the transformation, the bainite laths nucleate near to the grain boundaries and grow in a “side-by-side” mode in fine austenite grains, whereas in coarse austenite grains, the sympathetic nucleation at the broad side of the pre-existing laths causes the distribution of bainitic ferrite packets to be interlocked.

The Effects of Hot Deformation Parameters on the Size of Dynamically Recrystallised Austenite Grains of HSLA Steel

2019 ◽  
Author(s):  
Sebastian Gnapowski ◽  
Elżbieta Kalinowska- Ozgowicz ◽  
Mariusz Sniadkowski ◽  
Aleksandra Pietraszek
Keyword(s):  
Grain Size ◽  
Hot Deformation ◽  
Hsla Steel ◽  
Optical Microscope ◽  
Austenite Grain Size ◽  
Deformation Parameters ◽  
Austenite Grain ◽  
Austenite Grains ◽  
Ebsd Technique ◽  
Scanning Electron

This paper presents the results of investigations of the effects of hot deformation parameters in compression investigation on the austenite grain size in HSLA steel (0.16% C, 0.037% Nb, 0.004% Ti, 0.0098% N). The axisymmetric compression investigations were performed on cylindrical investigation specimens of d=1.2 using the Gleeble 3800 simulator. The strain rate=1s-1÷15.9s-1 and strain degree ε=1.2. Before deformation, the research specimens were austenitized at TA = 1100 ÷ 1250 °C. Metallographic observations of the primary austenite grains were conducted with an optical microscope, while the structure of dynamically recrystallized austenite, inherited by martensite, was examined by EBSD technique using a scanning electron microscope. Based on the analysis of investigation results, it was found that the size of dynamically recrystallized austenite grains in HSLA steel were clearly affected by hot compression parameters. In contrast, no significant impact of austenitising temperature on their size was found.

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.

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