STRAIN-RATE RESPONSE AND ITS EFFECT IN PLANE-STRAIN ABRASION OF METALS BY A WEDGE

The microstructural flow behavior of titanium and copper under uniaxial compression has been qualitatively related to the surface morphology and subsurface flow during plane strain abrasion. Uniaxial compression tests were carried out on titanium in the temperature range 298-673 K and copper at 298 K at strain rates in the range 0.1-100 s(-1). Titanium undergoes adiabatic shear banding at strain rates > 1 s(-1), the intensity of which decrease with decreasing strain rate and increasing temperature. This adiabatic shear banding is associated with a peak in the flow stress. Flow bands were observed in copper at low strain rates (less than or equal to s(-1)). There is no peak flow stress associated with the flow banding in copper. The adiabatic shear bands in titanium and flow bands in copper are sites of crack formation. It is found that the strain rate response of both these materials plays an important role in plane strain abrasion of these metals by tungsten carbide wedges. The intense adiabatic shear banding in titanium at 298 K results in intense cracking of the abraded track and the bow wave and inhibits subsurface flow. The subsurface flow was found to be high at 673 K where no intense adiabatic shear banding is observed. In copper subsurface cracking was observed. This is associated with the flow bands observed at low strain rates.