The effect of electric fields on metal surfaces is fairly well studied, resulting in numerous analytical models developed to understand the mechanisms ionization surface atoms observed at very high fields, as general behavior a this condition. However, derivation does not include explicitly structural properties metals, missing link between instantaneous effects owing applied field and consequent response result an extended application field. In present work, we have concurrent...

Numerical and Gleeble experimental data are combined to predict potential microstructure hardness profiles through the wall thickness of an induction hardened slurry transportation pipe made a recently developed 0.4 wt% C, Nb-microalloyed steel. The calculated thermal history various positions industrial (400 mm diameter, 10 thick) were with model that predicts phase transformations, microstructures final values on heating cooling along arbitrary cycles. accuracy profile predictions was...

Previously presented method of calculating local average gradients for solvingpartial differential equations (PDEs) is enhanced by accelerating it with graphics processingunits (GPUs) and combining a previous technique interpolating between grid points in thecalculation the instead using interpolation to create denser grid.For calculation GPUs, we have ported original naive Matlabimplementation C++ CUDA, after optimizing code observe speedupfactors more than two thousand, which largely due...

Understanding the steel microstructure formation during thermal treatments is crucial for controlling mechanical properties of a product. One important factors affecting subsequent development austenite grain size. To gain understanding effect temperature dependent nucleation and growth rates, as well providing tools quantitatively control size distribution, we have implemented cellular automata (CA) model describing heating, holding in temperatures above austenitization temperature. The...

A computational model based on the Johnson-Mehl-Avrami-Kolmogorov equation for simulating onset and kinetics of austenite to bainite martensite transformation has been fitted experimental continuous cooling data two different steels. We investigated how deformation below recrystallization temperature affected in comparison same steel undeformed state. The can be used simulate phase transformations occurring when is cooled along any path. fully coupled heat transfer conduction simulations...

A novel in-situ scanning electron microscope (SEM) characterization technique for observing phase transformation is developed and its results studied compared to well-founded experimental ex-situ methods as well numerical modelling of bainite formation. Phase kinetics are between the SEM, dilatometry test mean field Cellular Automata (CA) models. Microstructural evolution during EBSD CA model results. The method allows direct observation sheaf growth impingement. in combination with data can...

We examine a possible mechanism for the formation of protrusions on metallic surface held in sufficiently high electric field presence near-surface void. By means molecular dynamics simulations we show that tensile stress exerted Cu {110} with void can promote nucleation dislocations surface. These cause slip along {111} crystallographic planes leading to mass transport volume above find linear correlation between radius and maximum depth growth occur.

The stress exerted on a conducting material surface by an external electric field can cause plastic deformation if the is concentrated somewhere in material. Such concentration occur due to presence of near void. lead growth protrusion surface. To investigate conditions where such mechanism operate, we employ concurrent electrodynamics-molecular dynamics simulations, analyze distribution void using both molecular and finite element method, compare result analytical expression for located...

High-strength low alloy martensitic steels are produced by quenching methods to achieve a microstructure. The carbon supersaturation of the structure serves as driver for autotempering, which has advantageous effects on physical properties steel and may take place even at very high cooling rates. So far, precipitation kinetics during have been modelled with assuming no loss due diffusion from martensite into inter-lath austenite, partitioning modeled without considering precipitation,...

Dual-phase steels are generally used in the car industry due to high tensile strength and good formability, which obtained by a mixture of bainite ferrite phases. This microstructure is achieved through slow rate coil cooling. However, manufacturing dual-phase introduces various challenges such as instability cold rolling process. An important factor affecting this non-uniform cooling hot rolled strip. In rates not controlled there different thermal contacts during conveyance causing unequal...

Maximizing the performance of modern linear accelerators working with high gradient electromagnetic fields depends to a large extent on ability control breakdown rates near metal surfaces in accelerating structures. Nanoscale voids, presumably forming surface layers metals during technological processing, can be responsible for onset growth protrusion. We use finite element simulations study evolution annealed copper, single crystal copper and stainless steel that contain void under electric...

A combination of experimental and numerical approaches was applied for constructing a dynamic model thermomechanical processing, which used simulating laboratory rolling cooling, designing cooling path to enable phase transformation from austenite ultrafine (∼50–100 nm) bainitic laths. Physical simulation experiments were calibrating the models. Hot water conducted they numerically simulated. The calibrated models main processing stages affecting final microstructure evolution during scale...

A novel two-dimensional cellular automata model for simulating the formation of lath martensite and bainite in steels during cooling is presented. The parameterized using fitted Johnson-Mehl-Avrami-Kolmogorov (JMAK) Koistinen-Marburger equations by comparing predictions to scanning electron microscopy images actual microstructures after cooling. results this simulation can be used estimate fractions, shapes sizes different rates, which should offer new possibilities qualitative estimation...

Abstract A novel mathematical formulation is presented for describing growth of phase in solid‐to‐solid transformations and it applied austenite to ferrite transformation. The includes the effects transformation eigenstrains, local strains, as well partitioning diffusion. In current approach front modeled diffuse field, its propagation shown be described by advection equation, which reduces level‐set equation when proceeds only interface normal direction. considered thermally activated...

Abstract For constructing physical science based models in irregular numerical grids, an easy-to-implement method for solving partial differential equations has been developed and its accuracy evaluated by comparison to analytical solutions that are available simple initial boundary conditions. The is on approximating the local average gradients of a field fitting equation plane quantities at neighbouring grid positions then calculating estimate gradient from equations. results, solutions,...

We have analyzed in detail the mechanism leading to tip growth on a surface which operates via nucleation of dislocations near-surface void under tensile stress. derived simplified analytical model describing relevant physical factors related observed linearity between radius and maximum depth for occur. The is based direct numerical calculation atomic level stresses simulated system. Based present we can estimate this certain size given stress range beyond feasibility molecular dynamics...

Hot deformation and cooling together with the chemical composition define final mechanical properties of steel product. In order to control optimize desired properties, quantitative models are needed. this article we present our phase transformation model, which has been fitted experimental continuous data coupled own heat conduction computer simulation software. The fitting model enables accurate modeling. transfer allow non-uniform rates temperature distribution. development software full...

In order to study the coupled effect of rolling deformation, heat transfer and water cooling on microstructure formation a steel strip, multiscale multiphysical FE-model is developed. The deformation state temperature distribution strip after last pass are required calculate final microstructure. sub-model predicting accelerated implemented numerically. Final phase fractions calculated with Johnson-Mehl-Avrami-Kolmogorov equation for different parts object, taking into account non-uniform...

Abstract New CCT equations have been developed and optimized to simulate the start temperatures of austenite decomposition process in low-alloyed steels using experimental data published literature. Exceptionally, this optimization does not apply nominal compositions steels, but corresponding soluble grain boundaries calculated IDS software, depending on reported austenitization treatments steels. These compositions, rather than ones, are expected control decomposition, which usually...

Abstract Continuous cooling transformation (CCT) diagrams can be constructed by empirical methods, which is expensive and time consuming, or fitting a model to available experimental data. Examples of data-driven models implemented so far include regression models, artificial neural networks, k-Nearest Neighbours Random Forest. Gradient boosting machine (GBM) has been succesfully used in many learning applications, but not before modelling CCT-diagrams. This article presents novel way...

We present calculations of austenite to bainite phase transformation start for different cooling paths and steel compositions a method estimate the water required cool strip desired temperatures during line after industrial hot rolling. also quantitatively compare how alloying elements affect activation energy time proceed extent that it can be detected with dilatometer. This analysis used aid when designing suitable rolled products. The as input in more detailed microstructure models.