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Influence of sulfur on the processing map for hot working of nickel

Srinivasan, N and Prasad, YVRK (1992) Influence of sulfur on the processing map for hot working of nickel. In: Scripta Metallurgica et Materialia, 27 (3). pp. 309-312.

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Abstract

It is well known that sulfur segregates to grain boundaries in nickel and causes hot shortness [1-3]. At lower sulfnr levels (2-20 ppm), the concentration of sulfur at grain boundaries is sufficient to cause high temperature embrittlement while at higher concentrations, embrittlement occurs even at lower temperatures [2,3]. The aim of the present study is to examine the effect of sulfur impurity on the processing map for hot working of nickel. For this purpose, processing maps have been developed on pure nickel with no trace of sulfur and on commercial purity nickel with 20 ppm sulfiar. Since a separate study has revealed that the processing map is also influenced by the presence of carbon impurity, the carbon content in the two different nickel materials is kept nearly the same (0.02 wt%). The processing maps are developed using the approach of the Dynamic Materials Model [4,5] which considers the workpiece under hot working conditions as a dissipator of power. The variation of the efficiency of power dissipation given by [2m/(m+l)], where m is the strain rate senstivity of flow stress with temperature and strain rate, constitutes the power dissipation map. In addition, a continuum criterion for the onset of instabilities is used in combination with the power dissipation map for avoiding an unstable flow regime during hot deformation [5,6].

Item Type: Journal Article
Additional Information: Copyright of this article belongs to Elsevier.
Department/Centre: Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited: 09 Oct 2006
Last Modified: 19 Sep 2010 04:32
URI: http://eprints.iisc.ernet.in/id/eprint/8812

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