Reduction of friction coefficient of ultrafine-grained CP titanium

Friction coefficient is an important material property that affects the performance and service life of structural components that slide against each other. The frictional force consists of an adhesion force and a deformation force, producing an adhesion component and a deformation component of the friction coefficient. In this study, we compare the adhesion components of ultrafine-grained (UFG) Ti and coarse-grained (CG) Ti at temperatures from 25 to 800 °C and under a range of pressures. The UFG Ti samples were in two processing states: equal channel angular pressing (ECAP) for eight passes and ECAP+further cold rolling for 75% rolling strain. The experimental data indicate that ultrafine-grained structure results in lower adhesion component and consequently lower friction coefficient, which should in turn improve the wear property.