Study on Transformation Behavior of Retained Austenite in TRIP Steel

2013 ◽  
Vol 788 ◽  
pp. 100-104
Author(s):  
Heng Yong Shui ◽  
Di Tang ◽  
Qiang Liu
Keyword(s):  
Grain Boundaries ◽  
Trip Steel ◽  
Fracture Mechanism ◽  
Retained Austenite ◽  
Optical Metallography ◽  
Transformation Behavior ◽  
Stress Strain ◽  
Marked Selectivity ◽  
Austenite Grains

The microstructures of CR600TR steel were characterized using optical metallography, SEM, TEM and EBSD techniques, especially the transformation behavior of retained austenite and fracture mechanism of TRIP steel under stress-strain were studied in detail. It is discovered that there is marked selectivity for those retained austenite grains in their transition sequences: they are even dependent on the extension paths of stress-strain in steel and that curvatures of grain-boundaries which the retained austenite grains lie in.

Transformation Behavior of Retained Austenite in Hydroformed TRIP Steel

2002 ◽  
Vol 408-412 ◽  
pp. 1341-1346 ◽  
Author(s):  
Seung Taik Oh ◽  
Kwang Kyun Park ◽  
Heung Nam Han ◽  
Sung Ho Park ◽  
Kyu Hwan Oh
Keyword(s):  
Trip Steel ◽  
Retained Austenite ◽  
Transformation Behavior

Effect of the Austenite Interface on Pearlite Transformation Behavior

2018 ◽  
Vol 941 ◽  
pp. 639-644
Author(s):  
Hiroshi Hasegawa ◽  
Tatsuya Nakagaito ◽  
Yoshimasa Funakawa
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Intercritical Annealing ◽  
Transformation Behavior ◽  
Transformation Behaviour ◽  
Austenite Grain ◽  
Austenite Grains ◽  
Austenite Grain Boundary

The effect of the characteristics of austenite interface with ferrite on the pearlite transformation behaviour after intercritical annealing was investigated. Most austenite grains were situated mainly on ferrite grain boundaries and had the Kurdjumv-Sachs (K-S) or near K-S relationship to one of the neighbor ferrite grains before pearlite transformation. The pearlite transformation started mainly from the austenite grain boundary faced to ferrite. The pearlite transformation showed stasis. This indicates that some austenite is stabilized thermally against the pearlite transformation. The fraction of austenite having only the K-S or near K-S interface to neighbor ferrite grains was correspond to the fraction of austenite grains which does not include pearlite. The pearlite transformation was difficult to start from austenite interface having the K-S relationship to ferrite since the interface between austenite grains and ferrite grains was stabilized energetically in the case of their interface having the K-S relationship.

scholarly journals Evidence of Martensitic Transformation in Fe-Mn-Al Steel Similar to Maraging Steel

2020 ◽  
Vol 52 (1) ◽  
pp. 26-33
Author(s):  
Gurumayum Robert Kenedy ◽  
Yi-Jyun Lin ◽  
Wei-Chun Cheng
Keyword(s):  
Martensitic Transformation ◽  
Maraging Steel ◽  
Trip Steel ◽  
Single Phase ◽  
Lath Martensite ◽  
Al Alloy ◽  
Air Cooling ◽  
Small Temperature Gradient ◽  
Austenite Grains ◽  
Equilibrium Phases

AbstractThe Fe-Mn-Al steels claim a low density, and some fall into the category of transformation-induced plasticity (TRIP) steel. In Fe-Mn-Al TRIP steel development, phase transformations play an important role. Herein, the martensitic transformation of an Fe-16.7 Mn-3.4 Al ternary alloy (wt pct) was experimentally discovered, whose equilibrium phases are a single phase of austenite at 1373 K and dual phases of ferrite and austenite at low temperature. Ferritic lath martensite forms in the prior austenite grains after cooling from 1373 K under various cooling rates via quenching, air cooling, and furnace cooling. The formation mechanism of the ferritic lath martensite is different from that of traditional ferritic lath martensite in steel and quite similar to that in maraging steel. A slight strain energy coupled with a small temperature gradient can lead to the formation of ferritic lath martensite in the Fe-Mn-Al alloy after cooling from high temperature. It is also found that micro-twins exist in the ferritic lath martensite.

scholarly journals A Comparative Study of Acicular Ferrite Transformation Behavior between Surface and Interior in a Low C–Mn Steel by HT-LSCM

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 699
Author(s):  
Xiaojin Liu ◽  
Guo Yuan ◽  
Raja. Devesh Kumar Misra ◽  
Guodong Wang
Keyword(s):  
Grain Boundaries ◽  
Cooling Rate ◽  
Acicular Ferrite ◽  
Laser Scanning ◽  
Sample Surface ◽  
Surface Microstructure ◽  
In Situ Observation ◽  
Low Carbon ◽  
Transformation Behavior ◽  
Ferrite Transformation

In this study, the acicular ferrite transformation behavior of a Ti–Ca deoxidized low carbon steel was studied using a high-temperature laser scanning confocal microscopy (HT-LSCM). The in situ observation of the transformation behavior on the sample surface with different cooling rates was achieved by HT-LSCM. The microstructure between the surface and interior of the HT-LSCM sample was compared. The results showed that Ti–Ca oxide particles were effective sites for acicular ferrite (AF) nucleation. The start transformation temperature at grain boundaries and intragranular particles decreased with an increase in cooling rate, but the AF nucleation rate increased and the surface microstructure was more interlocked. The sample surface microstructure obtained at 3 °C/s was dominated by ferrite side plates, while the ferrite nucleating sites transferred from grain boundaries to intragranular particles when the cooling rate was 15 °C/s. Moreover, it was interesting that the microstructure and microhardness of the sample surface and interior were different. The AF dominating microstructure, obtained in the sample interior, was much finer than the sample surface, and the microhardness of the sample surface was much lower than the sample interior. The combined factors led to a coarse size of AF on the sample surface. AF formed at a higher temperature resulted in the coarse size. The available particles for AF nucleation on the sample surface were quite limited, such that hard impingement between AF plates was much weaker than that in the sample interior. In addition, the transformation stress in austenite on the sample surface could be largely released, which contributed to a coarser AF plate size. The coarse grain size, low dislocation concentration and low carbon content led to lower hardness on the sample surface.

scholarly journals Quantitative Description of External Force Induced Phase Transformation in Silicon–Manganese (Si–Mn) Transformation Induced Plasticity (TRIP) Steels

Materials ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 3781
Author(s):  
Zhongping He ◽  
Huachu Liu ◽  
Zhenyu Zhu ◽  
Weisen Zheng ◽  
Yanlin He ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Carbon Steel ◽  
Trip Steel ◽  
Retained Austenite ◽  
Low Carbon Steel ◽  
High Strength ◽  
High Plasticity ◽  
Low Carbon ◽  
Transformation Induced Plasticity ◽  
Trip Steels

Transformation Induced Plasticity (TRIP) steels with silicon–manganese (Si–Mn) as the main element have attracted a lot of attention and great interest from steel companies due to their low price, high strength, and high plasticity. Retained austenite is of primary importance as the source of high strength and high plasticity in Si–Mn TRIP steels. In this work, the cold rolled sheets of Si–Mn low carbon steel were treated with TRIP and Dual Phase (DP) treatment respectively. Then, the microstructure and composition of the Si–Mn low carbon steel were observed and tested. The static tensile test of TRIP steel and DP steel was carried out by a CMT5305 electronic universal testing machine. The self-built true stress–strain curve model of TRIP steel was verified. The simulation results were in good agreement with the experimental results. In addition, the phase transformation energy of retained austenite and the work borne by austenite in the sample during static stretching were calculated. The work done by austenite was 14.5 J, which was negligible compared with the total work of 217.8 J. The phase transformation energy absorption of retained austenite in the sample was 9.12 J. The role of retained austenite in TRIP steel is the absorption of excess energy at the key place where the fracture will occur, thereby increasing the elongation, so that the ferrite and bainite in the TRIP steel can absorb energy for a longer time and withstand more energy.

scholarly journals Enhancing the Mechanical Properties of a Hot Rolled High-Strength Steel Produced by Ultra-Fast Cooling and Q&P Process

Metals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 958 ◽  
Author(s):  
Teng Wu ◽  
Run Wu ◽  
Bin Liu ◽  
Wen Liang ◽  
Deqing Ke
Keyword(s):  
Retained Austenite ◽  
High Strength Steels ◽  
High Strength ◽  
Controlled Rolling ◽  
Grain Structure ◽  
Ultra Fast Cooling ◽  
Advanced High Strength Steels ◽  
Fast Cooling ◽  
Austenite Grains ◽  
Hot Rolled

The quenching and partitioning (Q&P) process of advanced high strength steels results in a significant enhancement in their strength and ductility. The development of controlled rolling and cooling technology provides an efficient tool for microstructural design in steels. This approach allows to control phase transformations in order to generate the desired microstructure in steel and, thus, to achieve the required properties. To refine grain structure in a Fe-Si-Mn-Nb steel and to generate the microstructure consisting of martensitic matrix with embedded retained austenite grains, hot rolling and pressing combined with ultrafast cooling and Q&P process is employed. The slender martensite in hot rolled Q&P steel improves the strength of test steel and the flake retained austenite improves the plasticity and work hardening ability through the Transformation Induced Plasticity (TRIP) effect.

Study on Elevated Temperature Impact Properties of 20MnSiV Steel

2012 ◽  
Vol 602-604 ◽  
pp. 313-317
Author(s):  
Da Yong You ◽  
Yin Lan Bai
Keyword(s):  
Elevated Temperature ◽  
Test Temperature ◽  
Fracture Mechanism ◽  
Room Temperature ◽  
Strain Softening ◽  
Practical Significance ◽  
Stress Strain ◽  
Strain Fracture ◽  
Temperature Impact ◽  
Longitudinal Extension

The test of 20MnSiV Ⅲ grade reinforced bar is carried out at room temperature and other nine temperatures: 100°C、200°C、300°C、400°C、500°C、600°C、700°C、800°C、900°C.The results show that, the highest impact absorbing energy 137J appeared when the test temperature is 200°C, while the lowest is 75.5J when the temperature is 600°C. While the test temperature is over 700°C and the sample is near damaged, strain softening and serious longitudinal extension is happened in the course of impact, and the gap of the sample can not result in the concentration of stress-strain, fracture mechanism of the material is changed, and then impact absorbing energy had no practical significance.

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