2015 Volume 56 Issue 658 Pages 986-992
The frictional behavior of galvannealed steel sheets (GA) depending on tool materials was investigated. GA having different ζ / δ1 phase intensity ratios was prepared as specimens. In addition, lubrication-treated GA was also prepared using these specimens as the base material. 4 kinds of tools composed of zinc alloy die casting (ZAS), ductile cast iron (FCD), alloy tool steel (SKD) and Cr-coated FCD were used as sliding tools in order to simulate actual press tools used in trials and mass-production. When the tool material was harder than those of the test specimens, the friction coefficient of GA increased with increasing amount of the ζ phase and the effect of lubrication treatment was clearly observed. However when the tool material was softer than those of the test specimens, the friction coefficient was constant independent of the existence of the ζ phase and lubrication treatment. The change in the frictional behavior was discussed from the viewpoint of the change in the frictional mechanism depending on the comparative hardness between the surfaces of the specimens and the tool materials.
