Study of a Novel Ultra-High Strength Steel with Adequate Ductility and Toughness by Quenching-Partitioning-Tempering Process

2010 ◽  
Vol 654-656 ◽  
pp. 37-40 ◽  
Author(s):  
Ying Wang ◽  
Shu Zhou ◽  
Zheng Hong Guo ◽  
Yong Hua Rong
Keyword(s):  
Electron Microscopy ◽  
High Strength Steel ◽  
High Strength Steels ◽  
High Strength ◽  
X Ray Diffraction ◽  
Advanced High Strength Steels ◽  
New Family ◽  
Transmission Electron ◽  
Ultra High Strength Steel ◽  
Base Steel

According to the design principle of microstructures for high strength steel and a new quenching-partitioning-tempering (Q-P-T) process recently proposed by Hsu, a microalloying Fe-Mn-Si base steel by the Q-P-T process has been designed. The results indicate that the Q-P-T steel exhibits ultra-high tensile strength combining with good ductility and toughness, and it is a new family of advanced high-strength steels. The microstructures of samples by different Q-P-T processes were characterized by means of optical microscopy, scanning electron microscopy, X-ray diffraction and transmission electron microscopy, and the relation between microstructures and mechanical properties was analyzed

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.

Influence of the Processing Variables on the Microstructure Evolution of a Bainitic Carbide-Free Steel

2016 ◽  
Vol 879 ◽  
pp. 867-872 ◽  
Author(s):  
M.C. Taboada ◽  
I. Gutiérrez ◽  
D. Jorge-Badiola ◽  
S.M.C. van Bohemen ◽  
F. Hisker ◽  
...  
Keyword(s):  
Retained Austenite ◽  
High Strength Steels ◽  
High Strength ◽  
High Volume ◽  
X Ray Diffraction ◽  
Tempered Martensite ◽  
Trip Steels ◽  
Volume Fractions ◽  
Advanced High Strength Steels ◽  
Processing Variables

New trends focused on achieving higher performance steels has led to a so-called 3rd Generation Advanced High Strength Steels (AHSS), in which the typical polygonal ferrite found in TRIP steels as a matrix phase is replaced by harder phases as Carbide-Free Bainite (CFB) and/or (tempered) martensite. Besides, large volume fractions of retained austenite (R.A.) with adequate stability are aimed for to improve the formability of the steels. Si containing steels are regarded as the most suitable to retard cementite formation and consequently reach high volume fractions of RA. In this work, CFB annealing schedules were applied to dilatometer samples of Fe-0.22C-2.0Mn-1.3Si. The overaging temperature TB was varied between 390 oC and 480 oC, and other processing variables investigated were the austenitizing temperature Taus, and the overaging holding time tB. The annealed samples analyzed with LOM, FEG-SEM, EBSD and X-ray diffraction techniques show that markedly different complex microstructures made up of bainite, ferrite, MA phase and retained austenite (R.A) are accomplished depending on the specific thermal cycle. These results are described in detail and discussed in relation to the dilatometry measurements.

Study on Micro-Mechanism of Crack Initiation and Propagation Induced by Inclusion in Ultra-High Strength Steel

2007 ◽  
Vol 353-358 ◽  
pp. 1185-1190 ◽  
Author(s):  
Yan Ping Zeng ◽  
Hong Mei Fan ◽  
Xi Shu Wang ◽  
Xi Shan Xie
Keyword(s):  
Crack Initiation ◽  
High Strength Steel ◽  
Harmful Effect ◽  
High Strength Steels ◽  
High Strength ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Crack Initiation And Propagation ◽  
Initiation And Propagation ◽  
Ultra High Strength Steel

Specially designed SEM in-situ tensile and fatigue tests have been conducted to trace the entire process of crack initiation and propagation till fracture in an ultra-high strength steel MA250. TiN is a typical inclusion and its average size is in the range of 8~10μm in MA250 steel. The micro-mechanism of the effect of TiN inclusion on crack initiation and propagation at tensile and fatigue tests both have been studied in detail. Experimental results show the harmful effect of TiN on tensile and fatigue properties both. This work is helpful to establish the practical life prediction model for the characteristic inclusion parameters in ultra-high strength steel components. It also enlightens us to eliminate TiN in the further development of ultra-high strength steels.

Quenching and Partitioning of Ni-Added High Strength Steels

2007 ◽  
Vol 539-543 ◽  
pp. 4476-4481 ◽  
Author(s):  
F.C. Rizzo ◽  
A.R. Martins ◽  
John G. Speer ◽  
David K. Matlock ◽  
A. Clarke ◽  
...  
Keyword(s):  
Retained Austenite ◽  
High Strength Steels ◽  
High Strength ◽  
Processing Parameters ◽  
Carbide Formation ◽  
X Ray Diffraction ◽  
Quenching And Partitioning ◽  
Steel Microstructure ◽  
Advanced High Strength Steels ◽  
Treatment Procedures

High strength steels containing significant fractions of retained austenite have been developed in recent years, and are the subject of growing commercial interest when associated with the TRIP phenomenon during deformation. A new process concept “quenching and partitioning” (Q&P) has been proposed by CSM/USA, and the results show the potential to create a new kind of steel microstructure with controlled amounts of retained austenite, enriched by carbon partitioning. Four steels containing C, Si, Mn, Ni, Cr and Mo, were designed with variation in the Ni and C content, aiming to decrease Bs temperature and to suppress carbide formation during the partitioning treatment. Several heat-treatment procedures were performed in specimens previously machined for tensile testing, while x-ray diffraction was used to determine the fraction of retained austenite. The tensile test results showed that except for the high C high Ni alloy, most of the processing conditions resulted in strengths superior to those of advanced high strength steels (AHSS), although it is importantly recognized that higher alloy additions were used in this study, in comparison with conventional AHSS grades.. A variety of strength and ductility combinations were observed, confirming the potential of the Q&P process and illustrating the strong influence of the final microstructure on the mechanical properties. Experimental results for samples partitioned at 400 °C indicate that higher ultimate tensile strength is associated with higher fraction of retained austenite for multiple heat treatments of each alloy investigated. The amount of retained austenite obtained was generally lower than that predicted by the model. Further studies are in progress to understand the influence of alloying and processing parameters (time/temperature) on the partitioning of carbon and precipitation of transition carbides.

scholarly journals Effect of Quenching and Partitioning Heat Treatment on the Fatigue Behavior of 42SiCr Steel

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1699
Author(s):  
Marco Thomä ◽  
Guntram Wagner
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Heat Treatment ◽  
Material Properties ◽  
Retained Austenite ◽  
Fatigue Behavior ◽  
High Strength Steels ◽  
High Strength ◽  
Advanced High Strength Steels ◽  
Scanning Electron

The manufacturing of advanced high-strength steels with enhanced ductility is a persistent aim of research. The ability of a material to absorb high loads while showing a high deformation behavior is a major task for many industrial fields like the mobility sector. Therefore, the material properties of advanced high-strength steels are one of the most important impact factors on the resulting cyclic fatigue behavior. To adjust advanced material properties, resulting in high tensile strengths as well as an enhanced ductility, the heat treatment process of quenching and partitioning (QP) was developed. The quenching takes place in a field between martensite start and martensite finish temperature and the subsequent partitioning is executed at slightly elevated temperatures. Regarding the sparsely investigated field of fatigue research on quenched and partitioned steels, the present work investigates the influence of a QP heat treatment on the resulting microstructure by light and scanning electron microscopy as well as on the mechanical properties such as tensile strength and resistance against fatigue regarding two different heat treatment conditions (QP1, QP2) in comparison to the cold-rolled base material of 42SiCr steel. Therefore, the microscopic analysis proved the presence of a characteristic quenched and partitioned microstructure consisting of a martensitic matrix and partial areas of retained austenite, whereas carbides were also present. Differences in the amount of retained austenite could be observed by using X-ray diffraction (XRD) for the different QP routes, which influence the mechanical properties resulting in higher tensile strength of about 2000 MPa for QP1 compared to about 1600 MPa for QP2. Furthermore, the transition for the fatigue limit was approximated by using stepwise load increase tests (LIT) and afterwards verified by constant amplitude tests (CAT) in accordance with the staircase method, whereas the QP 1 condition reached the highest fatigue strength of 900 MPa. Subsequent light and scanning electron microscopy of selected fractured surfaces and runouts showed a different behavior regarding the size of the fatigue fracture area and also differences in the microstructure of these runouts.

scholarly journals Bonded CFRP to high strength steels

2019 ◽  
Vol 52 (4) ◽  
pp. 222-235
Author(s):  
Mohsen Amraei ◽  
Lingjia Zong ◽  
Antti Ahola ◽  
Timo Björk
Keyword(s):  
Ultimate Strength ◽  
High Strength Steel ◽  
High Strength Steels ◽  
High Strength ◽  
High Modulus ◽  
Cfrp Laminates ◽  
Bond Performance ◽  
The Past ◽  
Ultra High Strength Steel ◽  
Series Of Experiments

Research on the bond performance of CFRP-strengthened steel have been done for the past years, but it has mainly focused on lower grades of steel. The performance of the bond between ultra-high modulus (UHM) CFRP and high/ultra-high strength steel (HSS/UHSS) is investigated in this paper. A series of experiments have been conducted, with single/double side-strengthened (SSS/DSS) HSS/UHSS with CFRP laminates using Araldite adhesive. It was found that strengthening up to the ultimate strength of the DSS specimens is feasible. However, debonding happens at the ultimate strength of SSS specimens.

Influence of the Weld Heat Input on the Electrochemical Behavior of the 921A High Strength Steel Welding Joints

2015 ◽  
Vol 817 ◽  
pp. 312-318
Author(s):  
Kai Wang ◽  
Jiang Long Yi ◽  
Shi Da Zheng ◽  
Chun Fu Guo ◽  
He Xin Chen ◽  
...  
Keyword(s):  
Electrochemical Behavior ◽  
Heat Input ◽  
High Strength Steel ◽  
High Strength Steels ◽  
High Strength ◽  
Cored Wire ◽  
Input Condition ◽  
Base Steel ◽  
Welding Joints ◽  
Weld Heat

Using the prepared gas-shielded flux-cored wire for welding 600MPa high strength steel, the 921A high strength steels were welded at different weld heat input condition of 10 kJ/cm, 15 kJ/cm and 20 kJ/cm. The influence of weld heat input on the electrochemical behavior of the 921A high strength steel welding joints were studied in this paper. The results show that, at different weld heat input condition, the linear polarization resistances (LPR) of all the welding joints welded by using the prepared flux-cored wire were close to that of the 921A base steel, as can be identified as the same LPR value at 15 kJ/cm weld heat input condition. By observing the surfaces of the linear polarized welding joints samples, it was found that the welding joint at 15 kJ/cm weld heat input had the smallest corrosive area by macro observing, showing the pitting corrosion by micro observing and presents the least corrosion pit.

Mechanical properties and microstructure of low carbon ultra-high strength steels (UHSS) microalloyed with boron

2012 ◽  
Vol 1373 ◽  
Author(s):  
I. Mejía ◽  
A. García de la Rosa ◽  
A. Bedolla-Jacuinde ◽  
J.M. Cabrera
Keyword(s):  
Mechanical Properties ◽  
Research Work ◽  
High Strength Steels ◽  
High Strength ◽  
Tensile Tests ◽  
Low Carbon ◽  
Advanced High Strength Steels ◽  
New Family ◽  
Ultra High Strength Steels ◽  
Hot Rolled

ABSTRACTThe aim of this research work is to study the effect of boron addition on mechanical properties and microstructure of a new family of low carbon NiCrVCu advanced high strength steels (AHSS). Experimental steels are thermo-mechanically processed (TMP) (hot-rolled+quenched). Results show that the microstructure of these steels contains bainite and martensite, predominantly, which nucleate along prior austenite grain boundaries (GB). On the other hand, tensile tests reveal that the TMP steels have YS (0.2% offset) of 978 MPa, UTS of 1140 MPa and EL of 18%. On the basis of exhibited microstructure and mechanical properties, these experimental steels are classified as bainitic-martensitic complex phase (CP) advanced ultra-high strength steels (UHSS).

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