A new effect of retained austenite on ductility enhancement in high-strength quenching–partitioning–tempering martensitic steel

2011 ◽  
Vol 528 (29-30) ◽  
pp. 8486-8491 ◽  
Author(s):  
Ke Zhang ◽  
Meihan Zhang ◽  
Zhenghong Guo ◽  
Nailu Chen ◽  
Yonghua Rong
Keyword(s):  
Retained Austenite ◽  
Martensitic Steel ◽  
High Strength

scholarly journals The Mechanism of High-Strength Quenching-Partitioning-Tempering Martensitic Steel at Elevated Temperatures

Crystals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 94 ◽  
Author(s):  
Ke Zhang ◽  
Maoyuan Zhu ◽  
Bitong Lan ◽  
Ping Liu ◽  
Wei Li ◽  
...  
Keyword(s):  
Retained Austenite ◽  
Elevated Temperatures ◽  
Martensitic Steel ◽  
Lath Martensite ◽  
Temperature Stability ◽  
High Strength ◽  
High Temperature Stability ◽  
High Deformation ◽  
Heat Treated ◽  
The Relationship

High-strength medium-carbon martensitic steel was heat treated through a quenching-partitioning-tempering (Q-P-T) treatment. Both the mechanism for improved ductility and the high temperature stability of austenite were investigated. The Q-P-T martensitic steel showed good products of strength and elongation (PSE) at various deformation temperatures ranging within 25–350 °C. The optimum PSE value (>57,738 MPa%) was achieved at 200 °C. The microstructure of the Q-P-T steel is constituted of laths martensite with dislocations, retained austenite located within lath martensite and small niobium carbides (NbC), and/or transitional ε-carbides that precipitated in the lath martensite. The good ductility can be mainly attributed to the laminar-like austenite that remained within the lath-martensite. The austenite can effectively enhance ductility through the effect of dislocation absorption by the retained austenite and through transformation-induced plasticity. The relationship between the microstructures and mechanical properties was investigated at high deformation temperatures.

Retained austenite-induced fire-resistance of a 690 MPa high strength steel

2021 ◽  
Vol 291 ◽  
pp. 129448
Author(s):  
L.J. Wei ◽  
X.M. Ji ◽  
Y.S. Yu ◽  
R.D.K. Misra ◽  
P.C. Liu ◽  
...  
Keyword(s):  
Fire Resistance ◽  
High Strength Steel ◽  
Retained Austenite ◽  
High Strength

scholarly journals Hot Deformation Behavior and Dynamic Recrystallization of Ultra High Strength Steel

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1239
Author(s):  
Liping Zhong ◽  
Bo Wang ◽  
Chundong Hu ◽  
Jieyu Zhang ◽  
Yu Yao
Keyword(s):  
Martensitic Steel ◽  
High Strength ◽  
Experimental Results ◽  
Hot Deformation Behavior ◽  
Thermal Compression ◽  
Forging Process ◽  
Finite Element Software ◽  
Ultra High Strength Steel ◽  
Recrystallized Grain Size ◽  
Deform 3D

In this paper, in order to improve the microstructure uniformity of an ultra-high strength martensitic steel with a strength greater than 2500 MPa developed by multi-directional forging in the laboratory, a single-pass hot compression experiment with the strain rate of 0.01 to 1 s−1 and a temperature of 800 to 1150 °C was conducted. Based on the experimental data, the material parameters were determined, the constitutive model considering the influence of work hardening, the recrystallization softening on the dislocation density, and the recrystallized grain size model were established. After introducing the model into the finite element software DEFORM-3D, the thermal compression experiment was simulated, and the results were consistent with the experimental results. The rule for obtaining forging stock with a uniform and refinement microstructure was acquired by comparing the simulation and the experimental results, which are helpful to formulate an appropriate forging process.

scholarly journals Heat Treatment Design for a QP Steel: Effect of Partitioning Temperature

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1136
Author(s):  
Marcel Carpio ◽  
Jessica Calvo ◽  
Omar García ◽  
Juan Pablo Pedraza ◽  
José María Cabrera
Keyword(s):  
Retained Austenite ◽  
High Strength Steels ◽  
High Strength ◽  
Tensile Tests ◽  
Quenching Temperature ◽  
Advanced High Strength Steels ◽  
New Family ◽  
Automotive Parts ◽  
Fresh Martensite ◽  
Industry Needs

Designing a new family of advanced high-strength steels (AHSSs) to develop automotive parts that cover early industry needs is the aim of many investigations. One of the candidates in the 3rd family of AHSS are the quenching and partitioning (QP) steels. These steels display an excellent relationship between strength and formability, making them able to fulfill the requirements of safety, while reducing automobile weight to enhance the performance during service. The main attribute of QP steels is the TRIP effect that retained austenite possesses, which allows a significant energy absorption during deformation. The present study is focused on evaluating some process parameters, especially the partitioning temperature, in the microstructures and mechanical properties attained during a QP process. An experimental steel (0.2C-3.5Mn-1.5Si (wt%)) was selected and heated according to the theoretical optimum quenching temperature. For this purpose, heat treatments in a quenching dilatometry and further microstructural and mechanical characterization were carried out by SEM, XRD, EBSD, and hardness and tensile tests, respectively. The samples showed a significant increment in the retained austenite at an increasing partitioning temperature, but with strong penalization on the final ductility due to the large amount of fresh martensite obtained as well.

scholarly journals Carbon Redistribution and Microstructural Evolution Study during Two-Stage Quenching and Partitioning Process of High-Strength Steels by Modeling

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2302 ◽  
Author(s):  
Yilin Wang ◽  
Huicheng Geng ◽  
Bin Zhu ◽  
Zijian Wang ◽  
Yisheng Zhang
Keyword(s):  
Retained Austenite ◽  
Volume Fraction ◽  
High Strength Steels ◽  
High Strength ◽  
Simulation Method ◽  
Low Carbon ◽  
Two Stage ◽  
Quenching And Partitioning ◽  
Carbon Redistribution ◽  
Carbon Martensite

The application of the quenching and partitioning (Q-P) process on advanced high-strength steels improves part ductility significantly with little decrease in strength. Moreover, the mechanical properties of high-strength steels can be further enhanced by the stepping-quenching-partitioning (S-Q-P) process. In this study, a two-stage quenching and partitioning (two-stage Q-P) process originating from the S-Q-P process of an advanced high-strength steel 30CrMnSi2Nb was analyzed by the simulation method, which consisted of two quenching processes and two partitioning processes. The carbon redistribution, interface migration, and phase transition during the two-stage Q-P process were investigated with different temperatures and partitioning times. The final microstructure of the material formed after the two-stage Q-P process was studied, as well as the volume fraction of the retained austenite. The simulation results indicate that a special microstructure can be obtained by appropriate parameters of the two-stage Q-P process. A mixed microstructure, characterized by alternating distribution of low carbon martensite laths, small-sized low-carbon martensite plates, retained austenite and high-carbon martensite plates, can be obtained. In addition, a peak value of the volume fraction of the stable retained austenite after the final quenching is obtained with proper partitioning time.

scholarly journals Effect of Quenching and Partitioning Temperatures in the Q-P Process on the Properties of AHSS with Various Amounts of Manganese and Silicon

2012 ◽  
Vol 706-709 ◽  
pp. 2734-2739 ◽  
Author(s):  
Hana Jirková ◽  
Ludmila Kučerová ◽  
Bohuslav Mašek
Keyword(s):  
Tensile Strength ◽  
Retained Austenite ◽  
Isothermal Holding ◽  
Bainitic Ferrite ◽  
High Strength Steels ◽  
High Strength ◽  
Experimental Program ◽  
Quenching Temperature ◽  
Quenching And Partitioning ◽  
Advanced High Strength Steels

The use of the combined influence of retained austenite and bainitic ferrite to improve strength and ductility has been known for many years from the treatment of multiphase steels. Recently, the very fine films of retained austenite along the martensitic laths have also become the centre of attention. This treatment is called the Q-P process (quenching and partitioning). In this experimental program the quenching temperature and the isothermal holding temperature for diffusion carbon distribution for three advanced high strength steels with carbon content of 0.43 % was examined. The alloying strategies have a different content of manganese and silicon, which leads to various martensite start and finish temperatures. The model treatment was carried out using a thermomechanical simulator. Tested regimes resulted in a tensile strength of over 2000MPa with a ductility of above 14 %. The increase of the partitioning temperature influenced the intensity of martensite tempering and caused the decrease of tensile strength by 400MPa down to 1600MPa and at the same time more than 10 % growth of ductility occurred, increasing it to more than 20%.

Application of Quenching-Partitioning-Tempering Process in Hot Rolled Plate Fabrication

2010 ◽  
Vol 654-656 ◽  
pp. 82-85 ◽  
Author(s):  
Shu Zhou ◽  
Ying Wang ◽  
Nai Lu Chen ◽  
Yong Hua Rong ◽  
Jian Feng Gu
Keyword(s):  
Mechanical Properties ◽  
Retained Austenite ◽  
High Strength Steels ◽  
High Strength ◽  
Significant Fraction ◽  
Rolled Plate ◽  
Quenching And Partitioning ◽  
Good Ductility ◽  
Hot Rolled ◽  
Rolled Plates

The quenching-partitioning-tempering (Q-P-T) process, based on the quenching and partitioning (Q&P) treatment, has been proposed for producing high strength steels containing significant fraction of film-like retained austenite and controlled amount of fine martensite laths. In this study, a set of Q-P-T processes for C-Mn-Si-Ni-Nb hot rolled plates are designed and realized. The steels with Q-P-T processes present a combination of high strength and relatively good ductility. The origin of such mechanical properties is revealed by microstructure characterization.

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