scholarly journals About the Memory of Transformation-Induced Plasticity in 35NCD16 Carbon Steel Subjected to Various Thermomechanical Histories

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1929
Author(s):  
Jose Jimenez ◽  
Lakhdar Taleb
Keyword(s):  
Applied Stress ◽  
Thermal Cycle ◽  
Ferritic Steel ◽  
Thermomechanical Loading ◽  
Reference Test ◽  
Austenite Transformation ◽  
Transformation Induced Plasticity ◽  
Applied Loading ◽  
First Case ◽  
Physical Phenomena

This study deals with Transformation-Induced Plasticity (TRIP) observed in the martensitic transformation of 35NCD16 ferritic steel. In this study, TRIP tests were carried out for two different cases: First, after only free dilatometric (FD) tests, which is used as the reference test for the considered applied stress; second, with TRIP tests being performed similarly to the first case (same thermal cycle, same applied stress) but with pre-thermomechanical loading histories applied. Such histories may be FD tests, TRIP tests, elastoplastic history, etc. The comparison between the results of TRIP test (a) and TRIP test (b) indicates if TRIP holds the memory of the applied loading histories. The current obtained results tell us that TRIP does not hold any significant memory. During the martensite à austenite transformation, the material may present recovery from strain hardening. Waiting for more details about the physical phenomena responsible for the absence of TRIP memory, one can point out the importance of this result as it enables one to use the same specimen for several TRIP tests. However, this result must be validated using other combinations of loading histories (such as multiaxial and cyclic, among others).

Effect of Minor Compressive Deformation in Austenite on Martensitic Transformation in Modified 9-12%Cr Ferritic Steel

2011 ◽  
Vol 299-300 ◽  
pp. 61-64 ◽  
Author(s):  
Chen Xi Liu ◽  
Yong Chang Liu ◽  
Dan Tian Zhang ◽  
Zhi Zhong Dong ◽  
Bao Qun Ning ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
High Resolution ◽  
Grain Boundary ◽  
Applied Stress ◽  
Ferritic Steel ◽  
Optical Microscope ◽  
Resistant Steel ◽  
Heat Resistant Steel ◽  
Mechanical Stabilization ◽  
Transformation Time

A modified high Cr ferritic heat-resistant steel was developed and subjected to the thermomechanical treatment. The effect of applied stress and temperature on martensitic transformation and microstructure was studied by using high-resolution differential dilatometer and optical microscope. Applied stress raises the amount of defection as dislocation and grain boundary defects, thus elevateMs. Applied stress also lead to the increase of transformation time due to the mechanical stabilization of austenite. Increase of applied stress or temperature would enhance these above effects.

scholarly journals On the correct use of mathematical constructions in physical models

2020 ◽  
pp. 7-27
Author(s):  
M. Belevich
Keyword(s):  
Mathematical Models ◽  
Physical Meaning ◽  
Fluid Model ◽  
Model Development ◽  
Physical Models ◽  
Model Modification ◽  
First Case ◽  
Viscous Fluid Model ◽  
Model Equations ◽  
Physical Phenomena

The physical limitations of the mathematical constructions used in developing or modifying mathematical models are discussed. All reasonings are illustrated by examples from fluid mechanics. The following topics are considered: means of description; correct approach to model modification and the physical meaning of model development stages. In the first case, the method of describing physical objects using numbers as well as corresponding restrictions are investigated, followed by developing general recommendations on procedures for modifying mathematical models of fluid dynamics. The well-known procedure of averaging the viscous fluid model equations to obtain the turbulent fluid model is used as an illustration. Since we are considering the models of physical phenomena, it is natural to provide physical interpretation for each stage of model development. Unfortunately, some of the transformations used are often treated as purely technical tricks, therefore denoting the lack of the physical meaning in such cases, which does not make a mathematical procedure unacceptable, but does mark out the model's place which requires reasonable interpretation. In this paper, we are considering two variants of this kind of interpretation, namely the case of using imaginary quantities, and the case of applying integral transformations. Meanwhile, all the above-mentioned restrictions are not always given due attention. Sometimes this leads to various undesirable consequences, including excessive task complication, implicit substitution of a declared problem with another one, or, finally, lack of solution to the formulated problem.

scholarly journals Some Remarks on Modelling and Simulation of Physical Phenomena

1997 ◽  
Vol 28 (3-4) ◽  
pp. 151-165 ◽  
Author(s):  
H. J. Bunge
Keyword(s):  
Mathematical Model ◽  
Computer Simulation ◽  
Mathematical Modelling ◽  
Modelling And Simulation ◽  
Theoretical Physics ◽  
Texture Formation ◽  
First Case ◽  
Non Linear ◽  
Non Linear Operator ◽  
Physical Phenomena

Mathematical modelling and computer simulation of physical phenomena is a rapidly growing field of work in all areas of pure and applied sciences. In principle, mathematical modelling of physical phenomena has been the field of theoretical physics from the very beginning of physics although the computer has increased the potentials of this method by many orders of magnitude. Modelling and simulation are often used as synonyms. It may, however, be meaningfull to distinguish the development of a mathematical model from its use in computer simulation. Also, a mathematical model in this sense must be distinguished from mathematical expressions interpolating experimental data. In the field of textures, models of texture formation, models of materials properties, as well as the combination of the two are being used. In this connection it is important whether a texture formation model is linear or non-linear. In the first case the texture formation operator can be reduced to the orientation space whereas a non-linear operator operates in the full texture space.

scholarly journals Role of Reversed Austenite Behavior in Determining Microstructure and Toughness of Advanced Medium Mn Steel by Welding Thermal Cycle

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2127 ◽  
Author(s):  
Yunxia Chen ◽  
Honghong Wang ◽  
Huan Cai ◽  
Junhui Li ◽  
Yongqing Chen
Keyword(s):  
Grain Size ◽  
Impact Toughness ◽  
Significant Role ◽  
Heat Affected Zone ◽  
Martensite Transformation ◽  
Thermal Cycle ◽  
Retained Austenite ◽  
Coarse Grained ◽  
Reversed Austenite ◽  
Austenite Transformation

Reversed austenite transformation behavior plays a significant role in determining the microstructure and mechanical properties of heat affected zones of steels, involving the nucleation and growth of reversed austenite. Confocal Laser Scanning Microscope (CLSM) was used in the present work to in situ observe the reversed austenite transformation by simulating welding thermal cycles for advance 5Mn steels. No thermal inertia was found on cooling process after temperature reached the peak temperature of 1320 °C. Therefore, too large grain was not generated in coarse-grained heat-affected zone (CGHAZ). The pre-existing film retained austenite in base metal and acted as additional favorable nucleation sites for reversed austenite during the thermal cycle. A much great nucleation number led to the finer grain in the fine-grained heat-affected zone (FGHAZ). The continuous cooling transformation for CGHAZ and FGHAZ revealed that the martensite was the main transformed product. Martensite transformation temperature (Tm) was higher in FGHAZ than in CGHAZ. Martensite transformation rate was higher in FGHAZ than in CGHAZ, which is due to the different grain size and assumed atom (Mn and C) segregation. Consequently, the softer martensite was measured in CGHAZ than in FGHAZ. Although 10~11% austenite retained in FGHAZ, the possible Transformation Induced Plasticity (TRIP) effect at −60 °C test temperature may lower the impact toughness to some degree. Therefore, the mean absorbed energy of 31, 39 and 42 J in CGHAZ and 56, 45 and 36 J in FGHAZ were exhibited at the same welding heat input. The more stable retained austenite was speculated to improve impact toughness in heat-affected zone (HAZ). For these 5Mn steels, reversed austenite plays a significant role in affecting impact toughness of heat-affected zones more than grain size.

scholarly journals Weld thermal simulation of API 5CT L80 grade steel

2021 ◽  
Author(s):  
Vinothkumar Palanisamy ◽  
Jan Ketil Solberg ◽  
Bjarne Salberg ◽  
Per Thomas Moe
Keyword(s):  
Mechanical Properties ◽  
Transformation Temperature ◽  
Thermal Cycle ◽  
Thermal Simulation ◽  
Austenite Transformation ◽  
Welding Method ◽  
Subsequent Tempering ◽  
Thermal Simulations ◽  
Hardness Values ◽  
Grade Steel

AbstractThe microstructure and mechanical properties of an API 5CT L80 casing grade steel (0.24C 0,4Si 1.4Mn CrNiCu) have been studied after performing weld thermal simulations (with and without subsequent tempering) applying a thermal cycle weld simulator. Specimens were subjected to three different peak temperatures (1300 °C, 1150 °C, 950 °C) and five different cooling rates (1 °C/s, 3 °C/s, 5 °C/s, 10 °C/s, 60 °C/s) through the austenite transformation temperature range. Based on the microstructure, hardness values, and toughness properties of the simulated specimens, thermal cycles were selected and recommended for welding of L80 components by the SAG-FW (shielded active gas forge welding) method.

Prediction of residual stresses in the heat affected zone

2004 ◽  
Vol 120 ◽  
pp. 705-712
Author(s):  
L. Taleb ◽  
S. Petit ◽  
J.-F. Jullien
Keyword(s):  
Residual Stresses ◽  
Phase Transformations ◽  
Thermal Cycle ◽  
Solid Phase ◽  
Axial Direction ◽  
Manganese Steel ◽  
Middle Zone ◽  
Finite Element Code ◽  
Transformation Induced Plasticity ◽  
The Face

In this paper the behavior of a disc made up of carbon manganese steel and subjected to an axisymmetric heating in its middle zone is considered. The applied thermal cycle generates localized metallurgical solid-solid phase transformations. Contrary to the study performed some years ago, the present work is concerned with relatively thick discs that lead to variable behavior according to axial direction. Experimentally, temperature and axial displacement of the face below have continuously been measured during tests. At the end of tests, the nature and the proportions of the final phases as well as residual stresses on both faces of the discs has also been assessed. These experimental results have been compared to numerical simulations using the finite element code ASTER, developed by Electricité de France (EDF), that enables to take into account the main mechanical consequences of phase transformations. From the obtained results it can be pointed out the significant importance to take into account the transformation induced plasticity (TRIP) phenomenon for better estimation of residual stresses.

Fatigue Crack Growth for Ferritic Steel Under Negative Stress Ratio

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Yoshihito Yamaguchi ◽  
Kunio Hasegawa ◽  
Yinsheng Li
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Fatigue Crack Growth ◽  
Intensity Factor ◽  
Crack Growth ◽  
Applied Stress ◽  
Ferritic Steel ◽  
Asme Code ◽  
Stress Ratios

Abstract The phenomenon of crack closure is important in the prediction of fatigue crack growth behavior. Many experimental data indicate crack closures during fatigue crack growths both under tensile–tensile loads and tensile–compressive loads at constant amplitude loading cycles, depending on the magnitude of applied load amplitudes and stress ratios. Appendix A-4300 of the ASME Code Section XI provides two equations of fatigue crack growth rates for ferritic steels expressed by stress intensity factor ranges at negative stress ratios. The boundary of the two equations is classified with the magnitude of applied stress intensity factor ranges, in consideration of the crack closures. However, the boundary value provided by the ASME Code Section XI is not technically well known. The objective of this paper is to investigate the influence of the magnitudes of the applied stress intensity factor ranges on the crack closures. Fatigue crack growth tests using ferritic steel specimens were performed in air environment at room and high temperatures. From the crack closures obtained by the tests, it was found a new boundary which is smaller than the definition given by the Appendix A-4300.

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