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Pittsburgh, PA, United States

Zhang H.,Quad Engineering Inc. | 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. Source

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. Source

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. Source

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. Source

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. Source

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