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Stiele H.,EFD Induction GmbH | Brand M.,Fraunhofer Institute for Mechanics of Materials | Asperheim J.-I.,EFD Induction A.s.
Elektrowaerme International | Year: 2010

Due to size and costs of big slewing rings, the common methods of experimental trial and error together with destructive test methods for verification of the inductive hardening process are limited. Thereby it is essential to simulate the hardening process in addition to the tests. With these simulations, it should be possible to get conclusions for the hardening pattern, the residual stress and distortion. With actually existing methods a fully three dimensional simulation is extremely time consuming. For that reason, a new method was developed that combines two dimensional with three dimensional simulation to shorten the time for calculation tremendously.


Grant
Agency: European Commission | Branch: H2020 | Program: MSCA-ITN-EID | Phase: MSCA-ITN-2015-EID | Award Amount: 2.11M | Year: 2015

The five partners EFD (Norway), SSAB, Outokumpu, and University of Oulu (Finland), and WIAS (Germany) propose an EID programme on Mathematics and Materials Science for Steel Production and Manufacturing, where eight PhD projects are jointly carried out, providing a unique interdisciplinary and inter-sectorial training opportunity. The research is focussed on three major topics - induction heating, phase transformations in steel alloys, ladle stirring. Two theses concern hardening: one is the hardening of helical and bevel gears by an optimized single or multi-frequency approach and the other is a novel idea about the hardening of the inner surface of pipes. Two of the theses are related to induction heating applications in the production of high-frequency welded pipes and for pre- and post-heating in the thermal cutting of steel plates. Two theses are concerned with phase transformations during steel production and the final two theses are related to secondary metallurgy in the ladle, optimal alloying strategies and an inverse problem related to stirring efficiency. Despite the fact that most theses projects deal with established processes, they are not fully understood nor fully controllable from a quality point of view. Improved and optimized process control requires quantitative mathematical modelling, simulation and optimization of the complex thermal cycles and thermal gradients experienced by the processed material. Such models require an understanding of the behaviour of the materials from a materials science and phase transformations perspective. Tailored industrial on-site trainings, customized courses in physical modelling and testing of steels as well as numerical simulation of induction heating and flow phenomena combined with scientific research in carefully selected topics on the interface of materials science and applied mathematics will provide the early stage researchers with excellent qualifications to pursue a career in academia or industry.


Markegard L.,EFD Induction a.s | Asperheim J.I.,EFD Induction a.s | Lai X.,Baosteel | Gu Z.,Baosteel
Pipe and Tube Nashville 2012 - Optimizing Operations Through Continuous Improvement | Year: 2012

The use of longitudinal seam-welded line pipe produced in continuous welding lines has increased in recent years. These pipes must apply to different standards, like API, ISO, DnV, etc. The trends are that the wall thicknesses of the pipes have increased and the materials used have set new demands on the heat treating process. Understanding the dynamics of the seam normalizing process and processes with intermediate quenching, during heating and cooling is, therefore, important in order to meet the different requirements. Process parameters like heating length/time, frequency and coil design, among others, all play a role on the final result. In the design, we use 2D finite element computations to investigate the influence of the process parameters. In addition, we have investigated the importance of positioning the heat treating coils correctly with regard to the weld seam. In our lab, we have run off-line tests on small samples following curves for heat-up, holding and cooling to simulate the heat treating process for outer and inner portions of the weld. A setup is tested with a short section of a pipe where a fixed coil is energized to simulate the heat treatment the pipe would receive passing through the different process stages. Finally we present results from a running line.


Ivanov D.,EFD Induction A.s. | Markegard L.,EFD Induction A.s. | Asperheim J.I.,EFD Induction A.s. | Kristoffersen H.,Swerea IVF
Journal of Materials Engineering and Performance | Year: 2013

The possibility to manage stress and strain in hardened parts might be beneficial for a number of induction-hardening applications. The most important of these benefits are the improvement of fatigue strength, avoidance of cracks, and minimization of distortion. An appropriate and powerful way to take the stress and strain into account during the development of a process is to make use of computer simulations. In-house developed and commercial software packages have been coupled to incorporate the electromagnetic task into the calculations. The simulations have been performed followed by analysis of the results. The influences of two different values of quenching intensity, strength of initial material structure, strength of austenite, surface power density-frequency-time combination, and workpiece diameter on the residual stress are studied. The influence of quenching intensity is confirmed by the series of experiments representing the external hardening of a cylinder with eight variations of quenching intensity. Measured by x-rays, the values of surface tangential stress are used as a dataset for verification of the model being used for analyses. © 2013 ASM International.


Svendsen K.,Telemark University College | Svendsen K.,EFD Induction AS | Hagen S.T.,Telemark University College
COMPEL - The International Journal for Computation and Mathematics in Electrical and Electronic Engineering | Year: 2011

Purpose - The purpose of this paper is to describe a model that can be used in the estimation of thermal fatigue limited service life of induction coils. Design/methodology/approach - Previous work indicates that the temperature of the cross section of an induction coil can be used to estimate thermal fatigue limited service life. This paper presents a model for estimating these temperatures based on a coupled model. Joule losses modelled in Flux2D are coupled with cooling modelled in Fluent3D. These models are controlled and combined by Python scripts that iterate the heat transfer and temperatures of heat exchange regions between the two domains. Findings - The combined model is shown to converge nicely. The model is also applied to an optimization problem where a high power loss, copper region is surrounding a wedge-shaped cooling channel. The point of the wedge was replaced by a radius that was optimized. The optimum was considered where the thermal fatigue service life is maximized, i.e. where the peak deviation from mean temperature in the cross section was at a minimum. The results show that the optimum corner radii are small, typically 0.25-0.5 mm. Originality/value - This is the first paper where the full model is presented and used to optimize specific cases. © 2011 Emerald Group Publishing Limited. All rights reserved.


Ivanov D.,EFD Induction AS | Markegard L.,EFD Induction AS
HTM - Journal of Heat Treatment and Materials | Year: 2016

Transformation plasticity is considered as a phenomenon limiting the actual stress for any specified strain rate under conditions of phase transformation. A one-dimensional model of a steel bar strained under martensitic transformation is provided. Discussion is limited to a series of accepted assumptions, such as athermal kinetics of martensite transformation, monotonic evolution of temperature and constant transformation plasticity parameter. An equivalent tangent modulus is deduced indicating the decisive parameters influencing the softening modes. The obtained model is utilized together with well-known transformation plasticity laws and martensite transformation kinetics to demonstrate an actual softening of steels under the martensitic transformation. © Carl Hanser Verlag GmbH & Co. KG.


Ivanov D.,EFD Induction as. | Asperheim J.I.,EFD Induction as. | Markegard L.,EFD Induction as.
ASM International - 28th Heat Treating Society Conference, HEAT TREATING 2015 | Year: 2015

The development of residual stress in an induction hardened small spur gear is numerically simulated. A full scale 3D simulation is utilized to obtain the results, providing the possibility to evaluate the complete distribution of residual stress in the hardened component. Electromagnetic and thermal solutions under induction heating conditions are obtained with Cedrat Flux 3D, whereas EDF Code Aster software is used for thermal simulation during the quenching stage, phase transformation, and stress-strain simulations. The simulated induction heating isotherms and distribution of residual stress are compared with experimental investigations done by Larregain et al. and Savaria et al. © 2015 ASM International®.


Ivanov D.,EFD Induction A.S. | Markegard L.,EFD Induction A.S. | Asperheim J.I.,EFD Induction A.S.
ASM Heat Treating Society - 26th Conference and Exposition: Gearing Up for Success | Year: 2011

The possibility to manage stress and strain in hardened parts might be beneficial for a number of induction hardening applications. The most important of these benefits is the improvement of fatigue strength, avoidance of cracks and minimization of distortion. An appropriate and powerful way to take the stress and strain into account during the development of a process is to make use of computer simulations. Own developed and commercial software packages have been coupled to incorporate the electromagnetic task into the calculations. The simulations have been performed with a following analysis of the results. The influences of two different values of quenching intensity, strength of initial material structure, strength of austenite, surface power density-frequency-time- combination, and work piece diameter on the residual stress are studied. © 2011 ASM International®.

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