scholarly journals Modelling of Reversed Austenite Formation and its Effect on Performance of Stainless Steel Components

2021 ◽  
pp. 1-29
Author(s):  
Sadie Louise Green ◽  
Hemantha Kumar Yeddu
Keyword(s):  
Stainless Steel ◽  
Phase Field ◽  
Volume Fraction ◽  
Phase Field Model ◽  
Austenite Formation ◽  
Reversed Austenite ◽  
Bumper Beam ◽  
Side Impacts ◽  
Diffusion Controlled ◽  
Shear Type

Abstract The kinetics of reversed austenite formation in 301 stainless steel and its effect on the deformation of an automobile front bumper beam are studied by using modelling approaches at different length scales. The diffusion-controlled reversed austenite formation is studied by using the JMAK model, based on the experimental data. The model can be used to predict the volume fraction of reversed austenite in a temperature range of 650 - 750 C. A 3D elastoplastic phase-field model is used to study the diffusionless shear-type reversed austenite formation in 301 steel at 760 C. The phase-field simulations show that reversion initiates at martensite lath boundaries and proceeds inwards of laths due to the high driving force at such high temperature. The effect of reversed austenite (RA) on the deformation of a bumper beam subjected to front and side impacts is studied by using finite element (FE) analysis. The FE simulations show that the presence of reversed austenite increased the critical speed at which the beam yielded and failed. RA fraction also affects the performance of the bumper beam.

An Approach for Modeling Transformation Plasticity Using a Phase Field Model

2011 ◽  
Vol 320 ◽  
pp. 285-290 ◽  
Author(s):  
Takuya Uehara
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Phase Field ◽  
Transformation Temperature ◽  
Field Model ◽  
Volume Fraction ◽  
Phase Field Model ◽  
Field Variable ◽  
Transformation Plasticity ◽  
Temperature Strain

In this paper, an approach for modeling transformation plasticity using a phase field model is presented. A conventional formula is utilized to represent the strain due to transformation plasticity as well as thermal expansion and transformation dilatation. A phase-field variable is introduced to express the state of phase in material instead of volume fraction, and numerical simulations under simplified conditions are demonstrated. As a result, the strain induced by phase transformation is suitably regenerated, and qualitatively appropriate temperature-strain curves are obtained. In addition, the effect of each parameter is investigated, and various dependencies, such as transformation temperature and stress, on the induced strain are demonstrated. It is then concluded that the results indicate the applicability of the presented model for practical use by adjusting the parameters.

Towards a Phase Field Model of the Microstructural Evolution of Duplex Steel with Experimental Verification

2012 ◽  
Vol 715-716 ◽  
pp. 635-642 ◽  
Author(s):  
S.O. Poulsen ◽  
Peter W. Voorhees ◽  
Erik M. Lauridsen
Keyword(s):  
Microstructural Evolution ◽  
Phase Field ◽  
Field Model ◽  
Phase Field Model ◽  
Dual Phase ◽  
Controlled Systems ◽  
Diffusion Controlled ◽  
Duplex Steel ◽  
Interphase Boundaries ◽  
Multi Phase

A phase field model to study the microstructural evolution of a polycrystalline dual-phase material with conserved phase fraction has been implemented, and 2D simulations have been performed. For 2D simulations, the model predicts the cubic growth well-known for diffusion-controlled systems. Some interphase boundaries are found to show a persistent non-constant curvature, which seems to be a feature of multi-phase materials. Finally, it is briefly outlined how this model is to be applied to investigate microstructural evolution in duplex steel.

Novel Phase-Field Simulation of Microstructure in Martensitic Materials

2008 ◽  
Author(s):  
Y. C. Shu ◽  
J. H. Yen
Keyword(s):  
Phase Field ◽  
Ground State ◽  
Volume Fraction ◽  
Phase Field Model ◽  
The Other ◽  
Energetic Cost ◽  
The Hierarchical Structure ◽  
Two Parameters ◽  
The Cost ◽  
Polynomial Expansions

A novel phase-field model of martensite suitable for microstructure simulation is developed here. It is motivated by the hierarchical structure of multirank laminates for establishing the rule of mixtures. As a result, a different choice of field variables, local volume fraction of laminates, is introduced to represent each martensitic variant. It provides an advantage of expressing the energy-well structure of martensitic variants in a unified fashion, instead of choosing the special polynomial expansions of conventional order parameters for a particular transformation. In addition, only two parameters are needed for microsturcture simulation. One is related to the energetic cost due to formation of the interface, and the other is the cost due to the deviation from the ground state energy. The framework is applied to the investigation of optimal microstructures for achieving large actuation strains for dome-shaped and tunnel-shaped microactuators. Finally, the framework is extended to ferroelectric domain simulation. Two cases are discussed: one is for the constrained modeling which restricts polarization remaining on the ground state, and the other is for the unconstrained modeling which allows polarization deviating from the ground state.

Phase Field Study of Concurrent Nucleation and Growth in a Diffusion-Controlled Solid-State Phase Transformation

2012 ◽  
Vol 490-495 ◽  
pp. 1140-1144 ◽  
Author(s):  
Gang Wang ◽  
De Chang Zeng ◽  
Zhong Wu Liu
Keyword(s):  
Phase Transformation ◽  
Phase Field ◽  
Phase Field Model ◽  
Field Method ◽  
Nucleation And Growth ◽  
Phase Field Method ◽  
Model Alloy ◽  
Transformation Kinetics ◽  
Diffusion Controlled ◽  
Solid State Phase Transformation

The concurrent nucleation and growth in a diffusion-controlled phase transformation is studied using the quantitative phase field method, and the transformation kinetics is obtained for a model alloy. The simulation results show that the simultaneous nucleation and growth of new phase can be described very well in the phase field model, and that the phase transformation is governed by the diffusion of solute atoms. The competition between nucleation and coarsening is also observed. The phase transformation kinetics is found to obey the JMAK equation.

scholarly journals Gas Bubble Evolution in Polycrystalline UMo Fuels Under Elastic-Plastic Deformation: A Phase-Field Model With Crystal-Plasticity

2021 ◽  
Vol 8 ◽  
Author(s):  
Shenyang Hu ◽  
Benjamin Beeler
Keyword(s):  
Plastic Deformation ◽  
Crystal Plasticity ◽  
Phase Field ◽  
Field Model ◽  
Volume Fraction ◽  
Phase Field Model ◽  
Gas Bubble ◽  
Elastic Plastic ◽  
Crystal Plasticity Model ◽  
Bubble Evolution

In monolithic UMo fuels, the interaction between the Al cladding and large gas bubble volumetric swelling causes both elastic-plastic and creep deformation. In this work, a phase-field model of gas bubble evolution in polycrystalline UMo under elastic-plastic deformation was developed for studying the dynamic interaction between evolving gas bubble/voids and deformation. A crystal plasticity model, which assumes that the plastic strain rate is proportional to resolved shear stresses of dislocation slip systems on their slip planes, was used to describe plastic deformation in polycrystalline UMo. Xe diffusion and gas bubble evolution are driven by the minimization of chemical and deformation energies in the phase-field model, while evolving gas bubble structure was used to update the mechanical properties in the crystal plasticity model. With the developed model, we simulated the effect of gas bubble structures (different volume fractions and internal gas pressures) on stress-strain curves and the effect of local stresses on gas bubble evolution. The results show that 1) the effective Young’s modulus and yield stress decrease with the increase of gas bubble volume fraction; 2) the hardening coefficient increases with the increase of gas bubble volume fraction, especially for gas bubbles with higher internal pressure; and 3) the pressure dependence of Xe thermodynamic and kinetic properties in addition to the local stress state determine gas bubble growth or shrinkage. The simulated results can serve as a guide to improve material property models for macroscale fuel performance modeling.

scholarly journals 3D Phase Field Modeling of Multi-Dendrites Evolution in Solidification and Validation by Synchrotron X-ray Tomography

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 520
Author(s):  
Shuo Wang ◽  
Zhipeng Guo ◽  
Jinwu Kang ◽  
Meishuai Zou ◽  
Xiaodong Li ◽  
...  
Keyword(s):  
Phase Field ◽  
Field Model ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Phase Field Model ◽  
Computationally Efficient ◽  
X Ray ◽  
Cu Alloy ◽  
Field Modeling ◽  
Micro Tomography

In this paper, the dynamics of multi-dendrite concurrent growth and coarsening of an Al-15 wt.% Cu alloy was studied using a highly computationally efficient 3D phase field model and real-time synchrotron X-ray micro-tomography. High fidelity multi-dendrite simulations were achieved and the results were compared directly with the time-evolved tomography datasets to quantify the relative importance of multi-dendritic growth and coarsening. Coarsening mechanisms under different solidification conditions were further elucidated. The dominant coarsening mechanisms change from small arm melting and interdendritic groove advancement to coalescence when the solid volume fraction approaches ~0.70. Both tomography experiments and phase field simulations indicated that multi-dendrite coarsening obeys the classical Lifshitz–Slyozov–Wagner theory Rn−R0n = kc(t−t0), but with a higher constant of n = 4.3.

Laminated Composite of Solidified TiC-TiB2 Ceramic to 1Cr18Ni9Ti Stainless Steel Achieved by Combustion Synthesis in High-Gravity Field

2014 ◽  
Vol 602-603 ◽  
pp. 473-478
Author(s):  
Hao Zhang ◽  
Zhong Min Zhao ◽  
Long Zhang ◽  
Ning Ding ◽  
Wei Min Ye
Keyword(s):  
Stainless Steel ◽  
Mechanical Activation ◽  
Gravity Field ◽  
Combustion Synthesis ◽  
Concentration Gradient ◽  
Volume Fraction ◽  
Laminated Composite ◽  
High Gravity ◽  
Diffusion Controlled ◽  
High Gravity Field

By combining mechanical activation and combustion synthesis in ultrahigh gravity field, the laminated composite of TiB2based ceramic to stainless steel was achieved in continuously-graded composition and microstructure, and within the Fe-Cr based intermediate Ti-Fe enriched carbides and fine TiB2platelets decreased gradually in size and volume fraction from the ceramic to stainless steel. Because of the sequent presence of thermal explosion, the dissolution of the molten stainless steel to TiC-TiB2liquid, the formation of diffusion-controlled concentration gradient from the ceramic liquid to the alloy liquid, the rapid sequent solidification of the ceramic and the alloy, the laminated composite is achieved in multilevel, scale-span hybrid microstructure that the different-size, different-morphology Fe-Cr alloy phases alternate with TiB2platelets and irregular TiC grains in size from micrometer to micro-nanometer.

scholarly journals Accelerated Ferrite-to-Austenite Transformation During Intercritical Annealing of Medium-Manganese Steels Due to Cold-Rolling

Metals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 926 ◽  
Author(s):  
Josh Mueller ◽  
David Matlock ◽  
John Speer ◽  
Emmanuel De Moor
Keyword(s):  
Phase Field ◽  
Volume Fraction ◽  
Intercritical Annealing ◽  
Cold Deformation ◽  
Low Carbon Steel ◽  
Austenite Formation ◽  
Low Carbon ◽  
Heating Rates ◽  
Nucleation Sites ◽  
Ultra Low Carbon Steel

Prior cold deformation is known to influence the ferrite-to-austenite (α → γ) transformation in medium-manganese (Mn) steels that occurs during intercritical annealing. In the present study, a 7Mn steel with ultra-low residual carbon content and varying amounts of prior cold deformation was intercritically annealed using various heating rates in a dilatometer. The study was conducted using an ultra-low carbon steel so that assessments of austenite formation during intercritical annealing would reflect the effects of cold deformation on the α → γ transformation and Mn partitioning and not effect cementite formation and dissolution or paraequilibrium partitioning induced austenite growth from carbon. Increasing prior cold deformation was found to decrease the Ac1 temperature, increase austenite volume fraction during intercritical annealing, and increase the amount of austenite nucleation sites. Phase field simulations were also conducted in an attempt to simulate the apparent accelerated α → γ transformation with increasing prior cold deformation. Mechanisms for accelerated α → γ transformation explored with phase field simulations included an increase in the amount of austenite nucleation sites and an increased Mn diffusivity in ferrite. Simulations with different amounts of austenite nucleation sites and Mn diffusivity in ferrite predicted significant changes in the austenite volume fraction during intercritical annealing.

Sign in / Sign up

Export Citation Format

Share Document