Size Distribution of Retained Austenite in Phosphorus-Containing TRIP Steels

2007 ◽  
Vol 539-543 ◽  
pp. 4321-4326 ◽  
Author(s):  
L. Zhao ◽  
Niels H. van Dijk ◽  
E.R. Peekstok ◽  
Ojin Tegus ◽  
Ekkes Brück ◽  
...  
Keyword(s):  
Optical Microscopy ◽  
Size Distribution ◽  
Retained Austenite ◽  
Volume Fraction ◽  
Strengthening Effect ◽  
Phosphorus Addition ◽  
Trip Steels ◽  
Average Grain Size ◽  
Austenite Grains ◽  
Neutron Depolarization

The present work investigates the influence of phosphorus addition on the size distribution of retained austenite in TRIP steels containing 0.01%, 0.09% and 0.14% phosphorus. The size of retained austenite is measured by means of neutron depolarization technique and optical microscopy. It is found that the addition of phosphorous increases the size of the larger intergranular and inter-ferritic austenite grains and therefore also increases the volume fraction of retained austenite due to the strengthening effect of phosphorous on the surrounding ferrite and bainite grains. For all phosphorous additions the most frequently observed austenite size is around 0.2 μm, which is probably corresponds to the interlath film-type retained austenite. The average grain size from the neutron depolarization technique agrees in general with that from the optical microscopy and it is suggested that the accuracy can be improved by further development of the data analysis by taking into account the preferred shape and orientation of the austenite grains.

Size Distribution of Retained Austenite in Phosphorus-Containing TRIP Steels

2007 ◽  
pp. 4321-4326
Author(s):  
L. Zhao ◽  
Niels H. van Dijk ◽  
E.R. Peekstok ◽  
O. Tegus ◽  
Ekkes Brück ◽  
...  
Keyword(s):  
Size Distribution ◽  
Retained Austenite ◽  
Trip Steels ◽  
Phosphorus Containing

Transformation Induced Plasticity (TRIP) Effect Used in Forming of Carbon CMnSi Steel

2005 ◽  
Vol 500-501 ◽  
pp. 461-470 ◽  
Author(s):  
Jiří Kliber ◽  
Bohuslav Mašek ◽  
Ondrej Zacek ◽  
H. Staňková
Keyword(s):  
Continuous Casting ◽  
Hot Rolling ◽  
Retained Austenite ◽  
Volume Fraction ◽  
Thermomechanical Processing ◽  
High Strength ◽  
Ferrite Matrix ◽  
Transformation Induced Plasticity ◽  
Trip Steels ◽  
Forming Temperature

Transformation induced plasticity (TRIP) steel combines high strength and high ductility that makes it particularly suitable for forming. Martensite within a ferrite matrix is usually obtained either by continuous casting of slabs followed by hot rolling (which is the fastest method, hence the most economical one, producing, however, relatively thick products) or by the continuous casting of slabs followed by hot rolling, cold rolling and annealing (the method used for thin products). High cooling rates, low coiling temperatures and low reduction during hot deformation were generally found to suppress the formation of polygonal ferrite and promote the presence of retained austenite. This paper focuses on development and modifications of two CMnSi-based TRIP steels with 0,23 % C;1,4 % Mn; 1,9 % Si; ( 0,08 % Nb) by means of laboratory thermomechanical processing. Description of experimental devices for the analysis of transformation plasticity under tensioncompression loading is given. Experiments were carried out on the simulator for thermaldeformation cycles SMITWELD and TANDEM was used for thermomechanical processing on the laboratory rolling mill. The maximum volume fraction of retained austenite and the resulting optimum combination of tensile strength and ductility were achieved in testing heats. Special attention was paid to volume fraction changes of single phases and to changes in morphology of phases. The results suggest that rather short isothermal bainite transformation times are sufficient to obtain TRIP microstructure. The influence of parameters of thermomechanical processing such as the amount of strain, forming temperature and austenitization time and temperature on microstructures of TRIP steels were evaluated.

scholarly journals Characterization of individual retained austenite grains and their stability in low-alloyed TRIP steels

2007 ◽  
Vol 55 (20) ◽  
pp. 6713-6723 ◽  
Author(s):  
E. Jimenez-Melero ◽  
N.H. van Dijk ◽  
L. Zhao ◽  
J. Sietsma ◽  
S.E. Offerman ◽  
...  
Keyword(s):  
Retained Austenite ◽  
Trip Steels ◽  
Austenite Grains

Effect of Phosphorus on Microstructure, Mechanical Properties, and Formation of Retained Austenite in TRIP Steels

2012 ◽  
Vol 508 ◽  
pp. 128-132 ◽  
Author(s):  
Eui Pyo Kwon ◽  
Shun Fujieda ◽  
Kozo Shinoda ◽  
Shigeru Suzuki
Keyword(s):  
Mechanical Properties ◽  
Carbon Concentration ◽  
Trip Steel ◽  
Retained Austenite ◽  
Volume Fraction ◽  
Transformation Induced Plasticity ◽  
Trip Steels ◽  
The Stability

In this Study, Influences of P on the Microstructure, Mechanical Properties, and Retained Austenite Characteristics in Transformation Induced Plasticity (TRIP) Steels Were Investigated. Microstructure of 0.2mass%P Containing TRIP Steel Was Inhomogeneous and it Resulted in Deterioration of the Mechanical Properties. Retained Austenite Characteristics such as Volume Fraction and Carbon Concentration Were Also Affected by P. The Stability of Retained Austenite in P Containing TRIP Steel Was Different from that in P-Free TRIP Steel. Such Difference in the Stability of Retained Austenite Was Attributed to the Effect of the Carbon Concentration in Retained Austenite as Well as their Different Microstructure.

Ultra Fine-Grained 6wt% Manganese TRIP Steel

2010 ◽  
Vol 654-656 ◽  
pp. 286-289 ◽  
Author(s):  
Sea Woong Lee ◽  
Kyoo Young Lee ◽  
Bruno C. De Cooman
Keyword(s):  
Mechanical Properties ◽  
Retained Austenite ◽  
Annealing Temperature ◽  
Volume Fraction ◽  
Intercritical Annealing ◽  
High Volume ◽  
Magnetic Saturation ◽  
Trip Steels ◽  
Fine Grained ◽  
Annealing Temperatures

Ultra-fine grained TRIP steels (UFG-TRIP) containing 6wt%Mn were produced by intercritical annealing. An ultra-fine grained microstructure with a grain size less than 1μm was obtained. The formation mechanism of the high volume fraction of retained austenite was investigated by dilatometry, XRD and magnetic saturation. The fraction of retained austenite was strongly dependent on the annealing temperature. The tensile properties were also found to be strongly influenced by the annealing temperature with poorer mechanical properties being observed at higher annealing temperatures. It was found that the stabilization of the retained austenite was both a composition and size-effect, made possible by the grain refinement due to the reversely transformed martensite.

scholarly journals TRIP Steels: A Multiscale Computational Simulation and Experimental Study of Heat Treatment and Mechanical Behavior

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 458
Author(s):  
Ioanna Papadioti ◽  
Ilias Bellas ◽  
Maria-Ioanna T. Tzini ◽  
Peter I. Christodoulou ◽  
Nikolaos Aravas
Keyword(s):  
Heat Treatment ◽  
Mechanical Behavior ◽  
Uniaxial Tension ◽  
Phase Field ◽  
Retained Austenite ◽  
Volume Fraction ◽  
Computational Simulation ◽  
Kinetics Model ◽  
Computer Assisted ◽  
Trip Steels

A multiscale investigation of the microstructure and the mechanical behavior of TRIP steels is presented. A multi-phase field model is employed to predict the microstructure of a low-alloy TRIP700 steel during a two-stage heat treatment. The resulting stability of retained austenite is examined through the M s σ temperature. The phase field results are experimentally validated and implemented into a model for the kinetics of retained austenite during strain-induced transformation. The kinetics model is calibrated by using experimental data for the evolution of the martensite volume fraction in uniaxial tension. The transformation kinetics model is used together with homogenization methods for non-linear composites to develop a constitutive model for the mechanical behavior of the TRIP steel. A methodology for the numerical integration of the constitutive equations is developed and the model is implemented in a general-purpose finite element program (ABAQUS). Necking of a bar in uniaxial tension is simulated and “forming limit diagrams” (FLDs) for sheets made of TRIP steels are calculated. The models developed provide an integrated simulation toolkit for the computer-assisted design of TRIP steels and can be used to translate mechanical property requirements into optimised microstructural characteristics and to identify the appropriate processing routes.

scholarly journals Influence of cold-rolling reduction on retained austenite texture in cold-rolled and intercritically annealed TRIP-assisted steel

2011 ◽  
Vol 44 (6) ◽  
pp. 1190-1197 ◽  
Author(s):  
E. Emadoddin ◽  
A. Akbarzadeh ◽  
R. Petrov ◽  
L. Kestens ◽  
H. Pirgazi
Keyword(s):  
Cold Rolling ◽  
Retained Austenite ◽  
Volume Fraction ◽  
High Strength ◽  
Industrial Applications ◽  
Rolling Reduction ◽  
Cubic Phase ◽  
Electron Backscattered Diffraction ◽  
Trip Steels ◽  
Cold Rolling Reduction

The newly developed multiphase transformation-induced plasticity (TRIP) steels are of interest for industrial applications because of their excellent combination of high strength and ductility. Their performance can be successfully controlled by designing an optimum balance in the volume fractions of ferrite, bainite and retained austenite. The characteristics of the retained austenite are considered to be the main key to achieving the desired final properties. Against this background, the effects of retained austenite characteristics, such as volume fraction, carbon concentration, size and shape, on the behaviour of TRIP steels have been studied. The crystallographic orientation of the retained austenite was measured by electron backscattered diffraction (EBSD). The effect of initial cold-rolling reduction on the microtexture development of the retained austenite was studied on an aluminium-containing TRIP steel. The results show that, by increasing the cold-rolling reduction before the final austempering, the main components of the face-centred cubic phase,i.e.copper, brass and Goss, dominate the texture of the retained austenite. In contrast, the copper and Goss components of the retained austenite are absent in the texture of lightly deformed sheets. The features of the preferred orientation of the retained austenite are discussed and explained in terms of the annealing texture of the recrystallized ferrite and bainite.

Texture and Orientation Relationships in Phosphorus Added TRIP Steels

2007 ◽  
Vol 539-543 ◽  
pp. 3347-3352 ◽  
Author(s):  
Kim Verbeken ◽  
L. Barbé ◽  
Bruno C. De Cooman
Keyword(s):  
Retained Austenite ◽  
Transformation Products ◽  
Maximum Intensity ◽  
Strong Indication ◽  
Orientation Relationships ◽  
Trip Steels ◽  
Electron Backscattering Diffraction ◽  
Orientation Relations ◽  
Detailed Evaluation ◽  
Austenite Grains

Phosphorus added TRIP steels were subjected to Electron BackScattering Diffraction (EBSD) measurements in order to study the texture of the three different phases and in order to evaluate the orientation relations that are active during the transformation of austenite to bainite. The retained austenite had a maximum intensity on the Brass component and the intensity gradually decreased along the alpha and the beta fibre. The intensity of both BCC phases was comparable, but the bainite texture displayed clear transformation products that could be related with the dominant Brass component of the intercritical austenite. A detailed evaluation of the crystallographic orientation relationships between about 360 retained austenite grains and their BCC neighbours was performed. Three relationships were considered, namely Kurdjumov-Sachs, Nishiyama-Wassermann and Pitsch. It was found that the majority of the austenite grains had at least one neighbour that could be related with one of the three orientation relationships. The Kurdjumov-Sachs relationship appeared to be dominant and no strong indication for variant selection could be retrieved from the studied data.

Mechanical Stability and Deformation-Induced Transformation of Retained Austenite in TRIP Steels at Low Temperatures

2017 ◽  
Vol 741 ◽  
pp. 36-41 ◽  
Author(s):  
Takayuki Yamashita ◽  
Norimitsu Koga ◽  
Osamu Umezawa
Keyword(s):  
Low Temperature ◽  
Work Hardening ◽  
Low Temperatures ◽  
Retained Austenite ◽  
Mechanical Stability ◽  
High Strain ◽  
Volume Fraction ◽  
Trip Steels ◽  
The Stability ◽  
Strength And Ductility

The tensile properties and the stability of retained austenite in TRIP steels with different volume fraction of retained austenite have been studied at low temperature. The steels showed a good valance of strength and ductility at 193 K. Their work-hardening rates were decreased linearly and kept a high value in the high strain regime at 193 K. The retained austenite was mostly transformed into martensite less than 10% strain at 193 K.

scholarly journals A Novel Cyclic-Quenching-ART for Stabilizing Austenite in Nb–Mo Micro-Alloyed Medium-Mn Steel

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1090 ◽  
Author(s):  
Chunquan Liu ◽  
Qichun Peng ◽  
Zhengliang Xue ◽  
Chengwei Yang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Retained Austenite ◽  
Volume Fraction ◽  
Total Elongation ◽  
Practical Significance ◽  
Strengthening Effect ◽  
Medium Mn Steel ◽  
Cyclic Quenching ◽  
Mn Steel

In the context of obtaining an excellent elongation and tensile-strength combination in the third generation of advanced high strength steel, we emphasized the practical significance of adjusting the retained austenite fraction and stability in medium-Mn steel to obtain better mechanical properties. A novel cyclic quenching and austenite reverse transformation (CQ-ART) was used to obtain a large retained austenite content in Fe-0.25C-3.98Mn-1.22Al-0.20Si-0.19Mo-0.03Nb (wt.%) Nb–Mo micro-alloyed medium-Mn steel. The results show that after twice cyclic quenching and ART, the alloy exhibited optimum comprehensive properties, characterized by an ultimate tensile strength of 838 MPa, a total elongation of 90.8%, a product of strength and elongation of 76.1 GPa%, and the volume fraction of austenite of approximately 62 vol.%. The stability of retained austenite was significantly improved with the increasing of the number of cyclic quenching. Moreover, the effects of CQ-ART on the microstructure evolution, mechanical properties, C/Mn partitioning behavior, and austenite stability were investigated. Further, the strengthening effect of microalloying elements Nb–Mo was also discussed.

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