The Frictional Mechanism on the Surface of Metal Being Plastically Deformed by Drawing

Abstract

To examine welding phenomena in deformation process, two-dimensional drawing-type friction tests have been carried out, using mild steel as the work metal. On the holder-surface a boundary lubrication state holds throughout the drawing process, while on the die-surface welding starts at the die exit and increases as the drawing progresses. The latter phenomenon is due to an expansion of the surface area. The frictional shear stress in the boundary lubrication region is proportional to the real contact pressure on both surfaces. The one at the welding region is nearly equal to the yield shear stress of the work metal.