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Olivier Joos
Abstract
Assessment of coupled damage mechanisms of work rolls for ferrous and non ferrous alloy hot rolling
Olivier Joos - 16 October 2009
The interruption of a hot strip mill in order to replace a work
roll is very expensive. This replacement is mainly motivated by
the strip surface quality degradation. The strip surface
quality is the mirror of the roll one. Because of numerous
coupled solicitations during service (oxidation,
abrasion/adhesion, thermal fatigue), the roll surface is
continuously damaged. The relative amplitude of each
solicitation depends of the roll position in the mill.
The productivity improvement is also linked to the roll life
increase, i.e. is linked to the enhancement of the roll
resistance to oxidation, abrasion/adhesion and/or thermal
cracking.
The aim of this study consists in correlating the microstructure
of 4 roll grades and the resistances against solicitations. At
the laboratory level, the solicitations are decoupled in order
to better study the impact of microstructural parameters on
damage mechanisms. After highlighting the grade microstructural
differences through numerous parameters (such as the
solidification structure; the type, chemical composition,
morphology and distribution of both primary and secondary
carbides ; the structure and chemical composition of the
matrix,...), we show firstly how these parameters influence the
grade oxidation mechanisms. Secondly we analyse the impact of
these parameters on wear mechanisms against coupled
solicitations: abrasion and oxidation on a one side, thermal
fatigue ant oxidation on the other side.
By weighing these parameters, it will be possible to optimize
the microstructure in function of the application.
Key words: hot rolling roll, friction, wear, oxidation, thermal fatigue
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