Abstract
This study aimed to investigate the effect of martensite particle size on dry sliding wear properties of dual phase PM steels. For this purpose, atomised iron powder with 0.3 wt.% graphite powder was cold pressed and sintered at 1200 °C. Some of the sintered specimens were annealed at intercritical heat treatment temperature of 750 °C and water-quenched to obtain coarse martensite region. The others were first austenitized at 890 °C, water-quenched and subsequently re-annealed at intercritical annealing temperature of 750 °C before rapidly water re-quenching to produce fine martensite size. Wear tests were performed in a pin-on-disc test device under 25 N load at 125 m min^-1 sliding speed. The wear rate decreased with decreasing martensite particle size due to the reducing inter-martensite particle spacing, increasing hardness of ferrite phases and decreasing cracking of fine martensite particles.

Key words
powder metallurgy steel, sintering, dual phase steel, martensite particle size, dry sliding wear

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