scholarly journals Effect of Morphology of Retained Austenite on Strength and Ductility of TRIP-aided Steel Sheets

2002 ◽  
Vol 88 (7) ◽  
pp. 400-405 ◽  
Author(s):  
Shunichi HASHIMOTO ◽  
Takahiro KASHIMA ◽  
Shushi IKEDA ◽  
Koh-ichi SUGIMOTO
Keyword(s):  
Retained Austenite ◽  
Steel Sheets ◽  
Strength And Ductility

Microstructure and Mechanical Properties of Cold-Rolled TRIP Steel Sheets

2011 ◽  
Vol 266 ◽  
pp. 280-283 ◽  
Author(s):  
Cai Nian Jing ◽  
Xiao Hui Chen ◽  
Ming Gang Wang ◽  
Qi Zhong Tian ◽  
Zuo Cheng Wang
Keyword(s):  
Retained Austenite ◽  
High Strength ◽  
Transformation Induced Plasticity ◽  
Trip Steels ◽  
Multiphase Microstructure ◽  
Steel Sheets ◽  
High Strength Level ◽  
Cold Rolled ◽  
Level 2 ◽  
Strength And Ductility

Transformation induced plasticity (TRIP) steels have complex multiphase microstructure composed of ferrite, bainite and retained austenite [1]. These metastable retained austenite can transforms into martensite during plastic deformation, which generates a TRIP effect resulting in excellent combination of high strength and ductility even at high strength level [2-5]. For this reason, the TRIP-aided steel sheets are suitable to fabricate automobile parts, as they can offer excellent formability without sacrifice the strength and safety requirement of the steel sheets. As a result, the development of TRIP-aided steels has been a very important issue in the automobile field.

Microstructure and Tensile Properties of TRIP-Aided Steel Sheet Subjected to Hot-Rolling and Austempering

2021 ◽  
Vol 1016 ◽  
pp. 732-737
Author(s):  
Junya Kobayashi ◽  
Hiroto Sawayama ◽  
Naoya Kakefuda ◽  
Goroh Itoh ◽  
Shigeru Kuraoto ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Hot Rolling ◽  
Manufacturing Process ◽  
Retained Austenite ◽  
Volume Fraction ◽  
Isothermal Holding ◽  
High Strength ◽  
Isothermal Transformation ◽  
Transformation Process ◽  
Steel Sheets

Various high strength steel sheets for weight reduction and safety improvement of vehicles have been developed. TRIP-aided steel with transformation induced plasticity of the retained austenite has high strength and ductility. Conventional TRIP-aided steels are subjected to austempering process after austenitizing. Generally, elongation and formability of TRIP-aided steel are improved by finely dispersed retained austenite in BCC phase matrix. The finely dispersed retained austenite and grain refinement of TRIP-aided steel can be achieved by hot rolling with heat treatment. Therefore, the improvement of mechanical properties of TRIP-aided steel is expected from the manufacturing process with hot rolling and then isothermal transformation process. In this study, thermomechanical heat treatment is performed by combining hot rolling and isothermal holding as the manufacturing process of TRIP-aided steel sheets. The complex phase matrix is obtained by hot rolling and then isothermal holding. Although the hardness of the hot rolled and isothermal held TRIP-aided steel is decreased, the volume fraction of retained austenite is increased.

Toward the Development of AHSS for Wear Resistant Applications

2018 ◽  
Vol 941 ◽  
pp. 568-573 ◽  
Author(s):  
Preston Wolfram ◽  
Christina Hensley ◽  
Ronald Youngblood ◽  
Rachael Stewart ◽  
Emmanuel de Moor ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Retained Austenite ◽  
Process Development ◽  
High Strength ◽  
Advanced High Strength Steel ◽  
Wear Resistant ◽  
Transformation Induced Plasticity ◽  
Enhance Wear Resistance ◽  
Improve Wear Resistance ◽  
Strength And Ductility

Advanced High Strength Steel (AHSS) developments have largely focused on automotive applications using metallurgical approaches to develop retained austenite-containing microstructures in a variety of new steels, using the transformation-induced plasticity (TRIP) effect to achieve better combinations of strength and ductility. These efforts have been extended in recent studies to explore the potential to improve wear resistance, using metastable retained austenite to enhance wear resistance for earth-moving and other applications. This paper provides selected highlights of the authors’ efforts to develop wear resistant steels using AHSS processing approaches. Some attractive product/process development opportunities are identified, and it appears that martensite-austenite microstructures produced using “quenching and partitioning” exhibit increased wear resistance.

Effects of Heat Treatment on Microstructure of High-Strength Manganese-Silicon Steels

2017 ◽  
Vol 270 ◽  
pp. 239-245
Author(s):  
Dagmar Bublíková ◽  
Štěpán Jeníček ◽  
Kateřina Opatová ◽  
Bohuslav Mašek
Keyword(s):  
Heat Treatment ◽  
Cooling Rate ◽  
Microstructure Evolution ◽  
Retained Austenite ◽  
Volume Fraction ◽  
High Strength ◽  
Quenching And Partitioning ◽  
Alloying Additions ◽  
New Procedures ◽  
Strength And Ductility

Today’s advanced steels are required to possess high strength and ductility. This can be accomplished by producing appropriate microstructures with a certain volume fraction of retained austenite. The resulting microstructure depends on material’s heat treatment and alloying. High ultimate strengths and sufficient elongation levels can be obtained by various methods, including quenching and partitioning (Q&P process). The present paper introduces new procedures aimed at simplifying this process with the use of material-technological modelling. Three experimental steels have been made and cast for this investigation, whose main alloying additions were manganese, silicon, chromium, molybdenum and nickel. The purpose of manganese addition was to depress the Ms and Mf temperatures. The Q&P process was carried out in a thermomechanical simulator for better and easier control. The heat treatment parameters were varied between the sequences and their effect on microstructure evolution was evaluated. They included the cooling rate, partitioning temperature and time at partitioning temperature. Microstructures including martensite with strength levels of more than 2000 MPa and elongation of 10–15 % were obtained.

Comparison of the Hardness-Toughness Relationship of Medium-Mn Steels after Q&T and Q&P Treatments*

2021 ◽  
Vol 76 (6) ◽  
pp. 445-457
Author(s):  
R. Schneider ◽  
S. Kaar ◽  
S. Schneider ◽  
D. Krizan ◽  
C. Sommitsch
Keyword(s):  
Tensile Testing ◽  
Retained Austenite ◽  
Room Temperature ◽  
Carbon Diffusion ◽  
Temperature Quenching ◽  
Optimum Parameters ◽  
The Stability ◽  
Relationship Of ◽  
Quenching And Tempering ◽  
Strength And Ductility

Abstract In contrast to quenching and tempering (Q&T), with quenching to room temperature, quenching and partitioning (Q&P) usually applies quenching to a temperature between Ms and room temperature. To stabilize a sufficient amount of retained austenite (RA), carbon diffusion from martensite into austenite and a prevention of cementite formation takes place during the successive partitioning step. Larger amount of RA, and its transformation into martensite during plastic deformation, provides Q&P treated steels with an enhanced combination of strength and ductility. In this investigation, the effect of different Q&T and Q&P treatments on the hardness-toughness relationship was determined. These results are compared with the RA contents and mechanical properties provided by tensile testing. The obtained results clearly demonstrate that the optimum parameters for strength and ductility do not match with the best combinations of hardness and toughness. Furthermore, the stability of the RA plays an important role in the understanding of toughness properties of the investigated Q&P steels.

scholarly journals Effect of Hot Working Parameters on Microstructure Evolution and Mechanical Properties of Ausformed Austempered Ductile Iron

2018 ◽  
Vol 925 ◽  
pp. 218-223 ◽  
Author(s):  
Mohamed Soliman ◽  
Adel Nofal ◽  
Heinz Palkowski
Keyword(s):  
Ductile Iron ◽  
Retained Austenite ◽  
Manganese Content ◽  
Mechanical Deformation ◽  
The Other ◽  
Total Deformation ◽  
Nucleation Sites ◽  
Transformation Stage ◽  
Working Parameters ◽  
Strength And Ductility

Three ductile irons with different aluminum-and manganese-content were subjected to two thermo-mechanical schedules. In the first schedule, a total deformation of φt= 0.3 is applied on the ductile irons in the austenitic region before the austempering process. In the second schedule, the materials are subjected to deformation of 0.2 in the austenitic region and deformation of 0.1 during austempering (ausforming). Mechanical deformation of austenite prior to the transformation “stage I” pronouncedly accelerated the transformation due to increasing the nucleation sites of ausferrite. This increase has its impact on enhancing the microstructural uniformity and refining the ausferrite platelets. On the other hand, the retained austenite content was not significantly affected by the applied ausforming. Remarkable increase in hardness, strength and ductility of the ausformed ductile iron due to the latter effects is observed.

scholarly journals Overcoming Strength-Ductility Trade-Off at Cryogenic Temperature of Low Carbon Low Alloy Steel via Controlling Retained Austenite Stability

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 157
Author(s):  
Xuelin Wang ◽  
Zhenjia Xie ◽  
Chengjia Shang ◽  
Gang Han
Keyword(s):  
Retained Austenite ◽  
Mechanical Stability ◽  
Testing Temperature ◽  
Low Carbon ◽  
Transformation Induced Plasticity ◽  
Strain Behavior ◽  
Austenite Stability ◽  
Work Hardening Rate ◽  
Multiphase Steel ◽  
Strength And Ductility

Stress–strain behavior of a low carbon low alloy multiphase steel with ferrite, tempered bainite, and retained austenite was studied at different cryogenic temperatures. Results indicated that both strength and ductility were enhanced with decreasing tensile testing temperature. The enhancement of both strength and ductility was attributed to the decreased mechanical stability of retained austenite with decreasing temperature, resulting in sufficient transformation induced plasticity (TRIP) effect for increasing work hardening rate.

Effect of Heat Treatment on Microstructure and Mechanical Properties of TRIP Steel Sheets Containing Aluminium

2011 ◽  
Vol 391-392 ◽  
pp. 554-558
Author(s):  
Yi Gao ◽  
Zhong Ping He ◽  
Yan Lin He ◽  
Lin Li ◽  
Ren Yuand Fu ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Trip Steel ◽  
Volume Fraction ◽  
Testing Machine ◽  
Steel Sheets ◽  
Key Factor ◽  
Simulation Testing ◽  
Gleeble 3500 ◽  
Strength And Ductility ◽  
Holding Temperature

Effect of heat treatment on microstructure of TRIP steel sheets containing aluminium was investigated on Gleeble 3500 thermal simulation testing machine. The microstructure evolution with variation of time and temperature was measured by means of optical metallography (OM) and X-ray stress analyzer. The tensile properties of TRIP steel at room temperature were also measured. It was shown that the maxium value of product of strength and ductility of 22858 MPa% was obtained by treatment of intercritical annealing temperature at 800 for 3 mins and bainitic holding temperature at 400 for 6 mins. The value of yield strength was mainly determinated by the volume fraction of bainite and the content of retained austenite was the key factor to result in optimum strength and ductility of TRIP steel. In addition, the properties of TRIP steel were markedly decreased because martensite, which was deleterious to the ductility, was present in microstructure of the steel soaking at bainitic temperature 350。C for 6 mins.

Development of Cold Rolling and Intercritical Annealing Texture in Two TRIP-Aided Steels

2005 ◽  
Vol 495-497 ◽  
pp. 513-518 ◽  
Author(s):  
E. Emadodin ◽  
A. Akbarzadeh
Keyword(s):  
Cold Rolling ◽  
Retained Austenite ◽  
Intercritical Annealing ◽  
High Strength ◽  
Texture Development ◽  
Al Content ◽  
Steel Sheets ◽  
Annealing Texture ◽  
Main Factors

High strength TRIP-aided steel sheets with high formability and better ductility are of industrial interest. Texture control and retained austenite characterization are considered as the main factors with respect to the formability and ductility. In this work, the effect of cold rolling and intercritical annealing on texture development has been investigated for two TRIP-aided steel sheets, which are different in Si and Al content. Experiments show that the cold rolling extends the a and g–fibers on these grades of steel. Intercretically annealing decreases the intensity of a–fiber and leads to sharpness of g–fiber, especially for Al steel.

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