RAIL GRINDING – A LABORATORY STUDY FOCUSED ON MATERIAL TRANSFORMATIONS DURING FACET GRINDING

Paper in proceeding, 2025

Pearlitic rail steels are susceptible to martensite formation in the surface layer due to rapid cooling after exposure to temperatures above the austenitisation temperature. The high thermal power imposed during rail grinding operations can result in the formation of a thin layer of martensite, called a white etching layer (WEL). This experimental grinding study aims to investigate the thermal impact of rail grinding in a realistic laboratory setup. The influence of applied power and grinding speed parameters during grinding operations on the microstructure of the altered surface layer were investigated on two common rail steel grades (R260 and R350HT). The grinding experiments demonstrated very small differences in transformed depth between the two rail grades, and the martensite hardness is similar. In transitions between facets, tempering of the martensite occurs that inevitably decreases the hardness locally. Increasing the feed rate, drastically decreases the depth of the transformed layer.