The influence of tempering and annealing on the microstructure and sliding wear response of G350 grey cast iron

The present study investigates the tribological properties of G350 grey cast iron in various microstructural conditions. Quench and temper heat treatments were conducted at four tempering temperatures, from 400 °C to 700 °C, to produce a range of tempered martensitic disc samples. Pins were slow furnace-cool annealed to produce a coarse pearlitic microstructure with some areas of ferrite. These samples were then used in pin-on-disc sliding wear tests. Hardness decreased with tempering temperature, from 400HV at 400 °C to 200HV at 700 °C. The two spheroidized carbide discs produced higher volume losses than the two acicular martensitic discs due to instability of the oxide layer on the softer substrate. Subsurface deformation was visible in the annealed pins and spheroidized discs which consisted of deformed cementite lamellae in the direction sliding and strained ferrite grains.