Tribological studies of friction stir processed steel alloy st14

Friction stir processing (FSP) was applied to st14 steel as a way to enhance the near-surface material properties. Tungsten-carbide alloy tool was used for processing at a rotating speed of 630 rpm, normal force of 5kN and an advancing speed of 100 mm/s with a tool tilt angle of 3°. All FSP experiments were carried out at room temperature with a single and double pass. Microstructural observations were carried out by employing optical and scanning electron microscopy (SEM) of the cross sections perpendicular to the tool traverse direction. Mechanical properties that include micro-hardness and wear resistance were evaluated in detail. The worn surface of the samples were examined by SEM of the surface composite samples. The high hardness of the processed samples produced significant benefit for friction and wear behavior of steel. The wear resistance of processed samples improved as compared to that of st14 steel.