Surface Quality Improvement Of Hot Dip Galvanized Steel Sheet, Using Hard Chrome Plated Skin Pass Mill Roll

by Nattha Panthong, Amika Saenkhum* Kim, Kyoung Beom*

Publisher - POSCO-Thailand Coated Steel, Thailand

Category - Engineering & IT

The chrome coating technology has been developed and applied in wide range of applications in the steel industries on the advantages of durability, wear resistance, and corrosion resistance etc. In Continuous Hot-Dip Galvanizing Line (CGL), Skin Pass Mill (SPM) is a key facility to improve mechanical properties and surface quality. Therefore SPM work roll quality is one of the most important factors that determine the surface quality of hot dip galvanized products. CGL SPM work rolls are generally thin hard chrome plated, around 10 μm thickness, in order that the rolls roughness should be retained under high rolling forces. It is difficult to obtain thin hard coating quality as it requires thin and uniform layer in whole roll surface within the short dipping time. Due to this difficulty and the high investment cost, there is only a limited number of hard chrome plating companies to achieve such coating quality and there are not many steel companies that have own chrome coating facilities. There have been many investigations about the effect of Cr-coated work roll, but there are not many results obtained from long-term actual line operation data. This paper investigated roll life time in comparison of Cr-coated and non Cr-coated work rolls with the controlled parameters and the effects on roll and steel surface roughness, the printed area ratio and the surface coating quality in the actual CGL operation line for long period.

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