Wear behavior of bainitic steels.

摘要

Railroad rails and wheels are produced from fully pearlitic eutectoid steel. In the last two decades increased axle loads have increased wear and other associated damage process in these materials. Conventional rail steels have, therefore, undergone modifications in alloy content and heat treatment aimed at decreasing the pearlite interlamellar spacing and increasing the strength. Further developments by these means are not easy to achieve and this has helped focus attention on steels with completely different microstructures.; Three experimental bainitic steels with 0.04, 0.1, and 0.52 wt% C and a 0.77 wt% C eutectoid pearlitic rail steel were used in this study. By employing continuous cooling and isothermal heat treatments different bainitic microstructures were obtained. Transmission electron microscopy was used to characterize microstructure.; The materials were investigated in an Amsler and a pin on disk wear rig under conditions of rolling/sliding and pure sliding respectively. The same trend in wear behavior of steels from both wear tests facilitated the development of a simple energy based model to compare pure sliding and rolling/sliding wear rates.; A detailed comparison of the wear characteristics of the bainitic and pearlitic steels revealed a comparable wear performance of bainitic steels under both wear situation. A strong influence of microstructural features on the wear behavior of one of the bainitic steels highlights the need to consider microstructure as well as mechanical properties in evaluating the wear behavior of a steel.; The research clearly demonstrated that steels with bainitic structure are potential candidates for wear resistant rail applications. The impetus to carry out further investigation on low carbon bainitic steel has, therefore been sustained.