ZnAlMg hot-dip galvanised steel sheets Tribology and tool wear

Abstract

For the last few years zinc magnesium alloys on cold rolled steel were investigated in detail because of their
potential to provide better corrosion protection than pure zinc coatings [1]. However, for introduction into the
automotive industry, it is also necessary to learn more about their tribological behavior. In the present work
the tribological potential of ZnAlMg hot dip galvanized steel sheets (HDG/ZM) was studied in terms of sliding
properties, adhesive and abrasive tool wear and compared to hot dip galvanized reference material (HDG/Z).
Different tribological tests were performed. The friction coefficient was determined directly by doing strip draw
tests at constant contact pressure. The deep drawing property was tested by forming model cups. Two different
oils, a pure corrosion protection oil and a prelube, were tested in each of the tribological tests. Abrasive tool
wear was studied according to the SEP1160 standard. Adhesive tool wear (galling) was characterized on
different tool material and compared to the results for hot dip galvanized reference material. HDG/ZM strips
showed improved friction behavior in the strip draw test when compared to classical hot dip galvanized
reference material. The abrasive tool wear is comparable to HDG/Z material, however, the galling was found to
be less than for pure zinc, and the morphology of the coating material transferred to the tool during deep
drawing is also different. This makes HDG//ZM an interesting system not only with respect to corrosion but
also in terms of tribology, thus providing clear advantages in formability.