2017 Volume 58 Issue 6 Pages 873-879
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. Four kinds of tools composed of zinc alloy die casting (ZAS), ductile cast iron (FCD), alloy tool steel (SKD) and Cr-coated FCD (CR) 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 the test specimens, the friction coefficient of the GA increased as the amount of the ζ phase increased, and the effect of the lubrication treatment was clearly observed. However when the tool material was softer than the test specimens, the friction coefficient was constant and 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 friction mechanism depending on the relative hardness of the surfaces of the specimens to the tool materials.
This Paper was Originally Published in Japanese in J. JSTP 56 (2015) 986–992.