THE GENERATION OF WEAR DEBRIS OF DIFFERENT MORPHOLOGY IN THE RUNNING-IN PROCESS OF IRON AND STEELS

This paper is a systematic study of the wear debris generated during the process of running in iron and steels, using a ferrographic analyser, scanning electron microscopy and energy-dispersive X-ray analysis. Wear tests were conducted on an MHK-500 (Timken) "ring-on-block" machine. The materials were 52100 bearing steel for the ring specimens, and 1045 steel with different degrees of hardness and G2500 cast iron for the block specimens. The regime for the running-in was kept constant, using a load of 375 N and a speed of 1.3 m s-1 for 60 min. This research involved mainly morphological and quantitative analyses of wear debris and the wear mechanisms during the running-in process for iron and steels. The ferrographic curves show an excellent correlation with the weight loss and surface roughness changes. The wear debris generated during running-in showed different morphologies, reflecting a composite wear mechanism of fatigue, adhesive, abrasive and corrosive wear. The fatigue wear can be considered as the dominant mechanism since the largest fraction of the wear debris was of the plate-like and spherical types.