scholarly journals Microstructure Analysis and Mechanical Properties of Low Alloy High Strength Quenched and Partitioned Steel

2016 ◽  
Vol 258 ◽  
pp. 574-578 ◽  
Author(s):  
Farnoosh Forouzan ◽  
Suresh Gunasekaran ◽  
Ali Hedayati ◽  
Esa Vuorinen ◽  
Frank Mücklich
Keyword(s):  
Mechanical Properties ◽  
Retained Austenite ◽  
Lath Martensite ◽  
High Strength ◽  
Microstructure Analysis ◽  
Quenching Temperature ◽  
Precipitate Formation ◽  
Quenching And Partitioning ◽  
Fine Grained ◽  
Impact Tests

Gleeble study of the quenching and partitioning (Q&P) process has been performed on Domex 960 steel (Fe, 0.08 %C, 1.79 %Mn, 0.23 %Si, 0.184 %Ti, and 0.038 %Al). The effect of different Q&P conditions on microstructure and mechanical properties were investigated. The aim of the process is to produce a fine grained microstructure for better ductility and controlled amounts of different micro-constituents to increase the strength and toughness simultaneously. Three different quenching temperatures, three partitioning temperatures and three partitioning times have been selected to process the 27 specimens by Gleeble® 1500. The specimens were characterized by means of OM, SEM, XRD, hardness and impact tests. It was found that, fine lath martensite with retained austenite is achievable without high amount of Si or Al in the composition although lack of these elements may cause the formation of carbides and decrease the available amount of carbon for partitioning into the austenite. The hardness increases as the quenching temperature is decreased, however, at highest partitioning temperature (640◦C) the hardness increases sharply due to extensive precipitate formation.

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.

Effect of Quenching and Partitioning Processing on Microstructure and Mechanical Properties of a Low Alloyed Steel

2018 ◽  
Vol 941 ◽  
pp. 52-57
Author(s):  
Bernd Pfleger ◽  
Marina Gruber ◽  
Gerald Ressel ◽  
Peter Gruber ◽  
Matthew Galler ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Strength ◽  
Phase Evolution ◽  
Tensile Tests ◽  
Austenite Phase ◽  
Phase Fraction ◽  
Quenching Temperature ◽  
Quenching And Partitioning ◽  
Low Alloyed Steel ◽  
A Minor

The concept of quenching and partitioning (Q&P) is a tool to generate steels with high strength and high ductility resulting from a relatively high amount of martensite and austenite. As the parameters of the Q&P treatment influence the strength and ductility properties, the goal of this work was to analyze the effects of varying quenching and partitioning temperatures on the phase evolution, on the retained austenite phase fraction and on the mechanical properties. The phase evolution during heat treatment was analyzed by dilatometer and the microstructure after processing was characterized by light microscopy in combination with color etching according to Klemm. The austenite phase fraction and its carbon content were determined by X-Ray diffraction and the mechanical properties were evaluated by tensile tests. It is shown that the quenching temperature has a minor impact on the phase fraction of austenite as well as its stabilization by carbon and thus, also the mechanical properties. Furthermore, austenite transformation during the partitioning treatment is illustrated.

scholarly journals Temperature Dependence of the Static and Dynamic Behaviour in a Quenching and Partitioning Processed Low-Si Steel

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 509 ◽  
Author(s):  
Florian Vercruysse ◽  
Carola Celada-Casero ◽  
Bernd M. Linke ◽  
Patricia Verleysen ◽  
Roumen H. Petrov
Keyword(s):  
Mechanical Properties ◽  
Retained Austenite ◽  
High Strength Steels ◽  
High Strength ◽  
Dynamic Strain ◽  
Strain Rates ◽  
Trip Effect ◽  
Quenching And Partitioning ◽  
Advanced High Strength Steels ◽  
Wide Range

Because of their excellent combination of strength and ductility, quenching and partitioning (Q & P) steels have a great chance of being added to the third generation of advanced high strength steels. The large ductility of Q & P steels arises from the presence of 10% to 15% of retained austenite which postpones necking due to the transformation induced plasticity (TRIP) effect. Moreover, Q & P steels show promising forming properties with favourable Lankford coefficients, while their planar anisotropy is low due to a weak texture. The stability of the metastable austenite is the key to obtain tailored properties for these steels. To become part of the newest generation of advanced high strength steels, Q & P steels have to preserve their mechanical properties at dynamic strain rates and over a wide range of temperatures. Therefore, in the present study, a low-Si Q & P steel was tested at temperatures from −40 °C to 80 °C and strain rates from 0.001 s−1 to 500 s−1. Results show that the mechanical properties are well-preserved at the lowest temperatures. Indeed, at −40 °C and room temperature, no significant loss of the deformation capacity is observed even at dynamic strain rates. This is attributed to the presence of a large fraction of austenite that is so (thermally) stable that it does not transform in the absence of deformation. In addition, the high stability of the austenite decreases the elongation at high test temperatures (80 °C). The additional adiabatic heating in the dynamic tests causes the largest reduction of the uniform strain for the samples tested at 80 °C. Quantification of the retained austenite fraction in the samples after testing confirmed that, at the highest temperature and strain rate, the TRIP effect is suppressed.

A New Hot Stamping Process with Quenching and Partitioning Treatment

2015 ◽  
Vol 1095 ◽  
pp. 673-676 ◽  
Author(s):  
Pei Xing Liu ◽  
Xiang Yun Yu ◽  
Kai Wang ◽  
Bin Zhu ◽  
Jian Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Retained Austenite ◽  
Hot Stamping ◽  
Quenching Temperature ◽  
Quenching And Partitioning ◽  
Servo Press ◽  
Stamping Process ◽  
Partitioning Time

A new hot stamping process with quenching and partitioning treatment is proposed in the paper. Compared to direct hot stamping process, the microstructures with some retained austenite not only including martensite are formed according to the constrained carbon equilibrium (CCE) model. During the new hot stamping process, tools with high temperature are used to control the quenching temperature (QT) between Ms and Mf, and the partitioning treatment of the part is also implemented in the tools by prolonging holding times. In this paper, different holding times (partitioning times) controlled by servo press, are used to research the influence of partitioning time on mechanical properties.

scholarly journals The Effect of Mn and Si on the Properties of Advanced High Strength Steels Processed by Quenching and Partitioning

2010 ◽  
Vol 654-656 ◽  
pp. 94-97 ◽  
Author(s):  
Bohuslav Mašek ◽  
Hana Jirková ◽  
Daniela Hauserova ◽  
Ludmila Kučerová ◽  
Danuše Klauberová
Keyword(s):  
Mechanical Properties ◽  
Retained Austenite ◽  
Volume Fraction ◽  
High Strength Steels ◽  
High Strength ◽  
Microstructural Development ◽  
X Ray Diffraction ◽  
Quenching And Partitioning ◽  
Advanced High Strength Steels ◽  
High Ultimate Strength

The concepts new types of materials are, for economic reasons, focused mainly on low alloyed steels with a good combination of strength and ductility. Suitable heat and thermo-mechanical treatments play an important role for the utilization of these materials. Different alloying strategies are used to influence phase transformations. The quenching and partitioning process (Q-P Process) is one of the heat treatment methods which can result in a high ultimate strength as well as a good ductility. However, these good properties can be obtained only if a sufficient amount of retained austenite is stabilized. The influence of different contents of manganese, silicon and chromium on microstructural development and mechanical properties were experimentally tested. Alloying elements were used to stabilize the retained austenite in the final microstructure and also to strengthen the solid solution. Ultimate strengths of over 2000MPa with ductility over 10% were reached after the optimization of the Q-P Process. The microstructures were analyzed using several microscopic methods; mechanical properties were determined by a tensile test and the volume fraction of the retained austenite was established by X-ray diffraction phase analysis.

Microstructure and Mechanical Properties of 0.15C-1.5Mn-0.3Si Steel Treated by Quenching and Partitioning Process

2014 ◽  
Vol 1063 ◽  
pp. 69-72
Author(s):  
Cai Nian Jing ◽  
Ji Chao Fan ◽  
Shu Bo Xu ◽  
Yi Sheng Zhang
Keyword(s):  
Mechanical Properties ◽  
Electron Microscope ◽  
Retained Austenite ◽  
Lath Martensite ◽  
Tensile Tests ◽  
Optical Microscope ◽  
Quenching And Partitioning ◽  
Microstructure And Mechanical Properties ◽  
Axial Tensile ◽  
Transmission Electron

In this paper, the microstructure and mechanical properties of 0.15C-1.5Mn-0.3Si steels after quenching and partitioning (Q&P) process was studied. The microstructure of experimental steels was characterized by optical microscope (OM), scan electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD), and mechanical properties were performed through uni-axial tensile tests. The microstructure evolution during Q&P process was also discussed together with mechanical properties. The investigated steels show excellent strength and ductility product of 10.76GPa% with retained austenite content of 11.08%. The microstructure mainly consists of lath martensite and retained austenite at room temperature, which promotes persistent work hardening during deformation.

scholarly journals EFFECTS OF COOLING RATE ON THE VOLUME FRACTION OF RETAINED AUSTENITE IN FORGINGS FROM HIGH-STRENGTH Mn-Si STEELS

2019 ◽  
Vol 25 (2) ◽  
pp. 93 ◽  
Author(s):  
Dagmar Bublíková ◽  
Hana Jirková ◽  
Kateřina Rubešová ◽  
Michal Peković ◽  
Julie Volkmannová ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Cooling Rate ◽  
Retained Austenite ◽  
Physical Simulation ◽  
Volume Fraction ◽  
High Strength ◽  
Hot Water ◽  
Quenching Temperature ◽  
Soaking Temperature

<p class="AMSmaintext"><span lang="EN-GB">Various ways are sought today to increase mechanical properties of steels while maintaining their good strength and ductility. Besides effective alloying strategies, one method involves preserving a certain amount of retained austenite in a martensitic matrix. The steel which was chosen as an experimental material for this investigation contained 2.5% manganese, 2.09% silicon and 1.34% chromium, with additions of nickel and molybdenum. An actual closed-die forged part was made of this steel. This forged part was fitted with thermocouples attached to its surface and placed in its interior and then treated using the Q&amp;P process. Q&amp;P process is characterized by rapid cooling from a soaking temperature to a quenching temperature, which is between the Ms and the Mf, and subsequent reheating to and holding at a partitioning temperature where retained austenite becomes stable. The quenchant was hot water. Cooling took place in a furnace. Heat treatment profiles were constructed from the thermocouple data and the process was then replicated in a thermomechanical simulator. The specimens obtained in this manner were examined using metallographic techniques. The effects of cooling rate on mechanical properties and the amount of retained austenite were assessed. The resultant ultimate strength was around 2100 MPa. Elongation and the amount of retained austenite were 15% and 17%, respectively. Microstructures and mechanical properties of the specimens were then compared to the real-world forged part in order to establish whether physical simulation could be employed for laboratory-based optimization of heat treatment of forgings.</span></p>

Mechanical Properties of Ultra-Fine Grained Fe-Cr-Ni Alloy Fabricated by ARB

2007 ◽  
Vol 26-28 ◽  
pp. 413-416 ◽  
Author(s):  
Taro Maekawa ◽  
Hiromoto Kitahara ◽  
Nobuhiro Tsuji
Keyword(s):  
Mechanical Properties ◽  
Volume Fraction ◽  
Lath Martensite ◽  
High Strength ◽  
Lamellar Spacing ◽  
Total Elongation ◽  
Austenitic Phase ◽  
Fine Grained ◽  
Ni Alloy ◽  
Martensite Structure

Microstructures and mechanical properties of Fe-15wt.%Cr-10wt.%Ni alloy ARB processed by various cycles were studied. The starting material showed lath martensite structure. However, the austenitic phase became stable by the high straining (ARB) above Af temperature. The volume fraction of austenitic phase greatly increased to around 90 % by 2 ARB cycles and nearly saturated at about 95 % after higher ARB cycles. The grain refinement progressed during the ARB, which leaded to the formation of ultrafine lamellar UFG austenitic microstructure with mean lamellar spacing of about 300 nm. The UFG Fe-Cr-Ni alloy performed both high strength and large elongation. Especially, the yield strength of the alloy ARB processed by 5 cycles reached to 900 MPa, and the total elongation was 40 %. The good ductility of the present specimens was attributed to the occurrence of transformation-induced plasticity (TRIP).

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.

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