Date of Award

2016

Degree Type

Thesis

Degree Name

M.A.Sc.

Department

Mechanical, Automotive, and Materials Engineering

First Advisor

A. R. Riahi

Second Advisor

M. Shafiei

Keywords

Al-Mg alloys, Aluminum adhesion, PVD coatings, Roll coating, Surface defects, Work roll

Rights

CC BY-NC-ND 4.0

Abstract

This study examines material transfer and adhesion from Al-Mg alloy samples to various PVD coatings deposited on AISI M2 steel rolls during hot rolling. It explores to examine if these PVD coatings can aid in extending the work roll life by either mitigating against material transfer or aiding in the early development of the roll coatings. Scanning electron microscopy (SEM) and focus ion beam (FIB) microscopy were used to investigate material transfer and adhesion to the surfaces of the work rolls. Aluminum and magnesium transfers were observed on all work rolls' surfaces from the 1st hot rolling pass. A two-way material transfer mechanism between the work roll and the rolled aluminum alloy surfaces was confirmed to determine the amount of material transfer on the work roll surfaces. The lubrication flow rate was reduced to examine the lubrication’s influence on the Al/Mg adhesion mitigation behavior of Cr and TiCN PVD coatings during hot rolling. The emulsion was identified as playing a significant role in the Al/Mg transfer and buildup of roll coatings on the work roll surfaces. Under both high and low lubrication conditions during hot rolling no damage was observed on the work roll surfaces which indicated that the PVD coatings were effective at extending the work roll life, although they were not able to totally mitigate against Al/Mg transfer and buildup on the work roll surfaces.

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