WHEMCO Inc.

Pittsburgh, PA, United States

WHEMCO Inc.

Pittsburgh, PA, United States

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Redkin K.V.,WHEMCO Inc. | Redkin K.V.,University of Pittsburgh | Hrizo C.,WHEMCO Inc. | Garcia C.I.,University of Pittsburgh
Materials Science and Technology Conference and Exhibition 2015, MS and T 2015 | Year: 2015

Spun cast bi-metallic rolls used in the early finishing stands of the hot strip mill are comprised of a highly alloyed working shell layer and ductile iron core. The high speed steel (HSS) shell, contacting the strip and backup roll (BUR), is subjected to extreme mill loading and environmental conditions. The campaign length, strip surface quality and mill performance depend on the characteristics of the HSS shell microstructure. In order to assess the local shell microstructural response, microscale image-based finite element models were developed. Actual scanning electron micrographs of HSS material, depicting possible radial variability in the shell, were converted into CAD models. The major microstructural factors considered were: eutectic vanadium and molybdenum-rich carbides embedded in a tempered martensitic matrix. To assess the microstructural response thermal and mechanical loading conditions were applied. The major structural factors were evaluated in terms of carbide morphology, volume fraction and type. Preliminary results were compared to actual observations, providing an improved understanding of the microscale phenomena. Copyright © 2015 MS&T15®.


Schleiden R.,United Foundries Inc. | Ballani J.,Whemco Inc.
AISTech - Iron and Steel Technology Conference Proceedings | Year: 2010

Centrifugally cast high chromium rolls (HiCr) can be used in selected cold rolling applications. The microstructure of HiCr rolls contains high hardness wear resistant carbides and a martensitic/low temperature bainite matrix which promotes good bruise resistance and strong wear characteristics. Traditional Cold Mills will start using HiCr rolls in Stand 1 and once proven progressively move to Stands 2 and beyond. The use of HiCr rolls in these applications eliminates the need for chrome plating and thus Hexavalent Cr in grinder effluent can be eliminated as an issue from an environmental perspective.


Nagy P.B.,University of Cincinnati | Hrizo C.M.,Whemco Inc. | Gundlach R.B.,Element Materials Technology
AISTech - Iron and Steel Technology Conference Proceedings | Year: 2013

The functionality of an eddy current test system depends on its ability to detect mechanical damage on the surface of mill work rolls. This study represents a ground-breaking first effort directed at better understanding, and potentially mitigating, the eddy current inspectability problem of indefinite chill work rolls reported by numerous users of hot strip mill work rolls. The reduced POD of shallow surface-breaking cracks is mainly caused by increased material noise and only to a much smaller, essentially negligible, degree by reduced flaw signal due to lower electric conductivity and magnetic permeability that are related to increased levels of retained austenite and possibly other differences in alloy content or microstructure. This study confirms the influence of material microstructure on the testability of indefinite chill work rolls. It is not surprising that varying roll types or rolls from various suppliers exhibit different testability degrees in the absence of an accepted eddy current capability specification. Such a capability standard must be relevant to the critical flaw size for crack growth or failure. While these results verify the influence of microstructural features on eddy current testability, they cannot be used to judge material quality or predict roll performance.


Zhang H.,Quad Engineering Inc. | Somers B.,Lehigh Heavy Forge | Marsden K.,WHEMCO Inc. | Freborg A.,Deformation Control Technology, Inc.
Iron and Steel Technology | Year: 2013

The article illustrates the potential of this design approach by examining a compact hot strip mill equipped with continuous variable crown (CVC) roll shifting and work roll bending shape control. Conventional machine design assumptions can oversimplify roll material response to applied force distribution. Work rolls (WR) and backup rolls (BUR) designed for flat rolling service incorporate a metallurgical compromise of wear resistance and damage tolerance. Alloy solidification behavior influences both the material microstructure of the working surface that governs performance and the bulk mechanical properties within the massive component cross- sections. The backup rolls are supplied in duplex or nionobloc tool steel quality, manufactured by either casting or forging routes. In all cases, the outer working zone of a mill roll exhibits a hardened micro- structure that generates a compressive stress state on the surface.


Redkin K.V.,WHEMCO Inc. | Redkin K.V.,University of Pittsburgh | Hrizo C.,WHEMCO Inc. | Garcia C.I.,University of Pittsburgh
AISTech - Iron and Steel Technology Conference Proceedings | Year: 2015

This paper discusses the application of a finite element model to analyze the deformation at the interface of a hot rolling stand. Actual rolling parameters from a hot strip mill were used as input data in this study. A sub-modeling finite element technique was applied to locate the highest stress-strain conditions in the roll barrel. The simulation results were used to conduct cyclic hot compression experiments on the roll materials, representing different grades within the High Speed Steel (HSS) family. Detailed microstructural analysis was performed on selected materials before and after deformation. The results of this investigation will be presented and discussed. AISTech 2015 Proceedings © 2015 by AIST


Nastac L.,University of Alabama | Marsden K.,Whemco Inc.
International Journal of Cast Metals Research | Year: 2013

Minimising macrosegregation and shrinkage defects during uphill teeming of medium carbon roll ingots has always presented a major technical challenge. Process improvements have been achieved by balancing the total heat input of a cast roll and the rate of heat extraction from the roll surface. Injecting dilute alloy through a submerged entry nozzle (SEN) into the net shaped roll ingot further mitigated the undesirable consequences of solute enrichment especially at the ingot centreline. Both the centreline segregation problems and midradius channel segregates can be significantly minimised, by combining these techniques. The objectives of this study are to determine the effect of mould thickness and material type (steel versus cast iron) on the centerline and especially on the midradius segregation, the solidification behavior in the transition region between the outer shell and the diluted interior region, as well as the mould durability. To accomplish these objectives, a multiphase multicomponent computational fluid dynamics (CFD) code was developed for studying the macrosegregation and shrinkage under various casting conditions for a 65 tonne, 1·6 m diameter steel roll processed via SEN. The developed CFD framework consists of solving for the volume fraction of phases (air and steel mixture), temperature, flow and solute balance in multicomponent alloy systems. © 2013 W. S. Maney & Son Ltd.


Redkin K.V.,University of Pittsburgh | Vipperman J.S.,University of Pittsburgh | Hnzo C.,WHEMCO Inc. | Schleiden R.,United Rolls Inc. | Garcia C.I.,University of Pittsburgh
Iron and Steel Technology | Year: 2013

A microstructural evaluation was conducted on a series of radial samples from the shell of high-speed steel work rolls produced by centrifugal spin casting. Continuous local transformations due to thermal gradients during heat treatments were simulated. Finite element modeling substructuring and image processing techniques were implemented to develop a multiscale model to simulate the local response of an individual microstructural constituents.


Liu Y.,Quad Engineering Inc. | Zhang H.,Quad Engineering Inc. | Somers B.,Lehigh Heavy Forge | Marsden K.,Whemco Inc. | Freborg A.,Deformation Control Technology, Inc.
AISTech - Iron and Steel Technology Conference Proceedings | Year: 2013

The present work began by investigating the global force distribution and inter-roll contact force distribution in CVC rolls of a compact hot strip mill with the advanced flat rolling simulation model developed by Quad Engineering. The stress fields within the work roll and backup roll were calculated using commercial FEA software for the force distributions predicted by the Quad model. Deformation Control Technologies predicted the residual stress patterns imparted by roll manufacturing, which were then superimposed onto the mechanical model to generate combined stress fields within the rolls. Fracture mechanics principles were applied to calculate the stress intensity factors associated with a hypothetical flaw in order to quantify fatigue stress response. Finally, the tolerable design flaw size criteria were mapped through the cross section of the rolls based on the calculated stress intensity distribution, incorporating the influence of a typical embedded flaw shape. Results facilitate development of specifications and inspection criteria for CVC rolls operating under real loading conditions.


Hrizo C.,WHEMCO Inc | Redkin K.,WHEMCO Inc | Marsden K.,WHEMCO Inc | Betts W.,Roll Metallurgy | Kapadia B.,Pittsburgh
AISTech - Iron and Steel Technology Conference Proceedings | Year: 2015

This paper examines the influence of microstructural characteristics on the performance attributes of complex phase indefinite chill (IC) work roll materials used in flat product rolling mills. Mechanical testing to assess the wear resistance and damage tolerance of conventional (IC) compared with developed (eIC) materials is discussed. Advanced scanning electron microscopy, thermodynamic-kinetic simulations were utilized to elucidate structure\property relationships in enhanced carbide (eIC) grades. © 2015 by AIST.


Nastac L.,University of Alabama | Hrizo C.,Whemco Inc. | Schleiden R.,Grace Inc
Materials Science and Technology Conference and Exhibition 2013, MS and T 2013 | Year: 2013

A numerical model was developed in this work to understand and optimize the centrifugal and static casting processes used in manufacturing HSS rolls. This model will help to further understand the complex solidification behavior of the HSS roll. Performance of the HSS roll requires proper formation and distribution of the VC and Mo2C carbides as well as the eutectic carbides, which is shown by dimensional analysis to be dominated by centrifugal buoyancy effects and solidification and carbide kinetics. The model includes a rheology-viscosity sub-model to address the interference between different moving particles or classes of particles of different sizes. The carbide redistribution model was successfully validated against experimental work. A parametric study was performed to determine the key variables that influence the distribution of the VC and Mo2C carbides and refine the HSS microstructure including the wash (coating) material, superheat, C content of the shell material and mold temperature. Copyright © 2013 MS&T'13®.

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