On the Unique Microstructure and Properties of Ultra-High Carbon Bearing Steel Alloyed with Different Aluminum Contents

In this study, ultra-high-carbon steels with 1.4% carbon content alloyed with three different aluminum contents, 2.0%, 4.0% and 6.0%, were studied on their tempering stability and temperature resistance. The results showed that the addition of Al significantly enhanced the tempering stability and temperature resistance of ultra-high-carbon steel. The addition of Al inhibited the transformation of e-carbide to cementite, suppressed the transition of martensite to ferrite and thus, endowed ultra-high carbon steels to maintain very high hardness during tempering within a wide range of temperature up to 500 °C. The present work provides a useful basis on which to develop bearing steel materials with low density and high hardness.