Replacing martensite with nanobainite in moderately alloyed carburised steel for better wear performance

Nanobainitic structures were produced in a low alloy carburised steel at temperatures of 200, 250 and 300 degrees C. Scanning electron microscope micrographs indicated bainitic ferrites formed with a thickness range of 30-150 nm. Wear test results revealed that the coefficient of friction for nanobainitic samples was smaller and narrower compared to that of the martensitic sample which showed higher and larger variations indicative of better wear performance for nanobainite samples. The wear mechanism of nanobainitic samples due to their tough matrix was oxidative which resulted in small debris and smaller fluctuations in coefficient of friction. The large variation in the coefficient of friction in the martensitic sample was believed to be because of the detaching of larger fragments from the worn surface.