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Thackray R.,University of Sheffield | Morris P.F.,Swinden Technology Center | Ridal K.,Sheffield Metallurgical and Engineering Association
Ironmaking and Steelmaking | Year: 2010

The 18th Annual Conference of the Sheffield Metallurgical and Engineering Association was held on the 7th and 8th July 2009 at the Endcliffe Conference Centre, University of Sheffield and attracted 98 delegates. The aim of the conference was to explore recent developments in the manufacture, evaluation and application of alloy steels, nickel-based superalloys and light metal components for critical engineering applications. Five technical sessions focused on nuclear energy, aerospace, energy supply chain and transport applications, and then considered some advanced technologies. © 2010 Maney Publishing. Source

Howe A.A.,University of Sheffield | Howe A.A.,Swinden Technology Center
Materials Science Forum | Year: 2010

Simplified models of micro-segregation are in common use in academia and industry. An issue regarding the accuracy of these approaches is addressed, before describing extensions required for the sponsor (Corus/Tata). It is shown that the adopted growth rate law of the solid is of equal importance as the diffusivity and the partition coefficient. By making the growth rate part of the solution rather than arbitrarily imposed (e.g. parabolic growth), dramatic errors are avoided. This approach has now been extended to the peritectic transformation in steel. Also included are dendrite arm coarsening and predictions of the solute profiles across the solid and their sub-solidus homogenization. The results of this streamlined model compare very well with experimental data and Finite Difference model calculations despite operating orders of magnitude more quickly. © (2010) Trans Tech Publications. Source

Farrugia D.C.J.,Swinden Technology Center
Ironmaking and Steelmaking | Year: 2010

The drive towards higher contribution free cutting steels with improved machinability and higher surface quality and consistency, together with the potential future implementation of the European legislation to promote lead substitutes (Bi, Te and high S), is leading to a requirement for improved understanding and control of as rolled surface quality, most critically for steels which have low ductility and a narrow temperature range for defect free rolling. Ductility breakup for the range of steel investigated (free cutting steel steels) is intrinsically complex with many interactions existing between casting, reheating and rolling. This is especially important during the transition from as cast to wrought structure, i.e. for thermomechanical and microstructural conditions acting in cogging/roughing mills, where the intrinsic reheated cast ductility of some machining steels can be as low as 10%. This paper builds upon previous studies for developing a more physical approach to predict the mechanisms of high temperature ductile damage acting at surface/subsurface and across the length scale of continuously cast free cutting steel billet feedstock during rolling. A methodology combining mechanical testing, modelling and characterisation has been developed to study effect of thermomechanical conditions such as triaxiality including inversion, principal stress, strain, strain path, strain rate and temperature as well as accounting for local microstructural heterogeneities such as MnS inclusions. This methodology has been used to refine the science of nucleation, growth and coalescence acting at high temperature for this range of low ductility steels during rolling. This knowledge has been put into practice with the establishment of regime maps and guidelines to minimise propensity of cracking during industrial rolling as well as being able to design effective schedules and grooves. Issues and future directions in terms of models and experimental technique development will also be highlighted. © 2010 Maney Publishing. Source

Peyton A.J.,University of Manchester | Yin W.,University of Manchester | Dickinson S.J.,University of Manchester | Davis C.L.,University of Birmingham | And 4 more authors.
Ironmaking and Steelmaking | Year: 2010

This paper describes the application of a new multifrequency sensor system to an industrial rod mill. The system operates by analysing the response of the rod to an excitation signal which contains a range of frequencies. The sensor system is able to successfully monitor the transformation of the material. Sensor configurations that could be deployed online have been considered and a prototype system has been built and tested in the Stelmor section of the Scunthorpe Rod Mill fitted in the enhanced cooling zone. Initial results are shown, demonstrating that the phase spectra is essentially unaffected by variations in lift-off and the lay pattern of the rod on the run-out table. The system was also able to detect different phase spectra from different grades of steel and also to detect features of the process which are known to affect microstructure. © 2010 Institute of Materials, Minerals and Mining. Source

Kardoulaki E.,Imperial College London | Lin J.,Imperial College London | Balint D.,Imperial College London | Farrugia D.,Swinden Technology Center
Key Engineering Materials | Year: 2014

High temperature tensile tests have been conducted on double-notched bars (DNBs) of varying notch acuity ratios (a/R), achieving a range of triaxiality, to evaluate the effect of stress state on edge cracking in hot rolling of free cutting steel. The conditions of the tensile tests are selected to physically simulate hot rolling condition of as-cast material to wrought structure. All experiments were conducted using a Gleeble 3800 thermo-mechanical testing system. The aim here is to develop a qualitative relationship between the activated damage mechanisms with respect to different stress states (arising from the sample geometry). Double-notch bars have been selected for this investigation as they enable the optical examination of the pre-failure mechanisms, captured in the unbroken notched area. The damage features have been observed at the notch areas and different damage mechanisms have been identified for different stress state deforming at different temperatures. © (2014) Trans Tech Publications, Switzerland. Source

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