Sliding wear of medium-carbon bainitic/martensitic/austenitic steel treated by short-term low-temperature austempering

A medium-carbon Si–Mn–Ni–Cr–Mo alloyed (300M) steel was austempered for various short periods at its martensite-starting temperature of 285 °C to seek improved sliding wear resistance as compared the traditional martensitic and bainitic steels. Reciprocating tests were performed against a WC/Co ball counterpart constant load 49 N. The samples characterised using field emission SEM, XRD hardness testing. associated mechanisms analysed SEM cross-sectional TEM. results revealed that austempering time 6 min produced refined arrays initial nano-bainitic ferrite laths inter-lath filmy austenite majority martensite retained austenite, while microstructure remained with austenite. unchanged as-quenched 6.4 GPa. Simultaneously coefficient decreased by 41% from 2.67 1.58 × 10 -15 m 3 N -1 , which is also superior both tempered 1.65 lower bainite 1.87 . Increasing 20 60 resulted in coefficients 1.38 2.18 respectively. has been explained induced evolution, especially carbon partitioning stabilisation high-stress found be dominated severe shear deformation, nano-laminate structured top layer. Delamination take place within embrittled nano-laminates. • novel heat treatment obtain martensite/austenite/nano-bainite microstructure. dry-sliding quenched steel. Detailed characterization evolution FEG-SEM, delamination mechanism caused hardening embrittlement attributed stabilised due partitioning.