Microstructure modelling of hot deformation of Al–1%Mg alloy

This study presents the application of the finite elementmethod and intelligent systems techniques to the prediction of microstructural mapping for aluminium alloys. Here, the material within each finite element is defined using a hybrid model. The hybrid model is based on neuro-fuzzy and physically based components and it has been combined with the finite element technique. The model simulates the evolution of the internal state variables (i.e. dislocation density, subgrain size and subgrain boundary misorientation) and their effect on the recrystallisation behaviour of the stock. This paper presents the theory behind the model development, the integration between the numerical techniques, and the application of the technique to a hot rolling operation using aluminium, 1 wt% magnesium alloy. Furthermore, experimental data from plane strain compression (PSC) tests and rolling are used to validate the modelling outcome. The results show that the recrystallisation kinetics agree well with the experimental results for different annealing times. This hybrid approach has proved to be more accurate than conventional methods using empirical equations

A Comprehensive Case Study of Macrosegregation in a Steel Ingot

This is the author accepted manuscript. The final version is available from Springer via http://dx.doi.org/10.1007/s11663-015-0386-yA case study is presented that examines the macrosegregation and grain structure present in a 12-tonne steel ingot, which was cast for experimental purposes. Details of the casting procedure were well documented and the resulting ingot was characterized using a number of techniques that measured chemical segregation, shrinkage, and porosity. The formation of the porosity and segregation patterns is discussed in reference to the particular grain structure observed in the ingot. It is hoped that this case study can be used as a tool for the validation of future macromodels.This work was undertaken as part of a Project sponsored by Rolls-Royce Power Nuclear plc in collaboration with Sheffield Forgemasters International

Estimation of cooling rates during close-coupled gas atomization using secondary dendrite arm spacing measurement

Al-4 wt pct Cu alloy has been gas atomized using a commercial close-coupled gas-atomization system. The resulting metal powders have been sieved into six size fractions, and the SDAS has been determined using electron microscopy. Cooling rates for the powders have been estimated using a range of published conversion factors for Al-Cu alloy, with reasonable agreement being found between sources. We find that cooling rates are very low relative to those often quoted for gas-atomized powders, of the order of 10 K s for sub-38 μm powders. We believe that a number of numerical studies of gas atomization have overestimated the cooling rate during solidification, probably as a consequence of overestimating the differential velocity between the gas and the particles. From the cooling rates measured in the current study, we estimate that such velocities are unlikely to exceed 20 m s

Liquid phase sintering of austenitic stainless steel 316L powder using tin and nickel

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN026894 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Hot rolled aluminium alloys texture via hybrid modelling

During the thermomechanical processing of aluminium alloys, the material experiences a complex history of temperature, time, and strain path. The rolling and deformation process has an effect on the evolution of the material texture which can be modelled using finite element models of the rolling process and a Taylor model for texture evolution. This paper explores the potential of modelling the rolling and texture evolution processes using data-driven systems models to reduce the computational time and achieve better accuracy

Application of a fundamental friction model to the hot rolling of steel

Abstract not available

Finite element modelling of a multipass research mill

The use of advanced numerical techniques such as finite element analysis for the modelling of industrial processes has increased dramatically in recent years. This paper describes how this technique has been applied to the modelling of a multipass research mill at the Corus IJmuiden Technology Centre. The model presented in this work has been used to simulate hot rolling of aluminium alloy AA5182. A commercial general-purpose finite element program MARC has been used to create a thermo-mechanically coupled model which assumes plane strain conditions. The results of this model are compared with experimental measurements carried out on the pilot mill

Modelling surface thermal damage to hot mill rolls

Surface thermal damage to hot mill work roll materials was investigated using twin-disc high-temperature laboratory test rig under conditions that are relevant to those of the early stands of a hot strip rolling mill. Two typical roll grades were tested: high speed tool steel and high-carbon high-chromium steel. Mill data were scaled down to suit the test sample dimensions and used to calculate the thermal cycle, contact times and contact pressure. A coupled thermomechanical model based on the finite element method was developed to predict the temperature distribution within the core and at the surface of the roll test samples. The predictions of the model showed good agreement with the temperatures measured using embedded thermocouples at several depths in the sub-surface of the roll test sample. After high temperature testing, the test samples were sectioned and prepared by conventional metallography for microscopic analysis. The thermally induced surface damage in the test samples were found to exhibit similar features to those observed in actual mill work rolls during service, especially the high-carbon-high-chromium steel, which showed a greater extent of surface thermal damage than the high speed tool steel test samples. Based on the results, it is concluded that the new test rig was proven capable of producing thermal damage in a consistent and reproducible manner and, thus, it can be regarded as a valuable off-line test resource to assist in further understanding the work roll surface deterioration phenomena. © 2007.R.D. Mercado-Solis, J. Talamantes-Silva, J.H. Beynon and M.A.L. Hernandez-Rodrigue

Multi-modal simulation for microstructural and property prediction for Al alloy hot rolling

This study presents the application of FE modelling and intelligent systems techniques to the prediction of microstructural mapping for aluminium alloys. Here, the material within each finite element is defined using a set of non-linear physically-based equations. These are then solved in real-time using a semi-physical grey-box model. This model is based on a neuro-fuzzy approach and it has been embedded within the FE technique. The model maps the evolution of the internal state variables (i.e. dislocation density, subgrain size and subgrain boundary misorientation) and their effect on the recrystallisation behaviour of the stock. This paper presents the model development, the integration between the numerical techniques, and the application of the technique to a hot rolling operation using an Aluminium, 1wt% Magnesium alloy. In addition, the developed model includes a CA (Cellular Automata) level to represent inhomogeneous nature of microstructural beheviour