The effects of varying contact pressure and creepage on the early stag
es of rolling contact fatigue in three pearlitic rail steels have been
investigated in the laboratory under water lubricated conditions. Tn
the test machine used, a non-contacting eddy current probe detected ve
ry small fatigue cracks and was used to stop tests before spalling cou
ld destroy the fatigue initiation sites in order that the metallograph
y of crack initiation could be undertaken. Crack morphologies similar
to those found in wheel-rail contact have been observed. Except at the
highest creepages and contact stress used, there was little evidence
that manganese sulphide inclusions contributed to crack initiation. In
contrast, hard oxide inclusions did contribute to initiation. The hea
d-hardened grade eutectoid steel had the best resistance to rolling co
ntact fatigue, The naturally hard eutectoid steel was the next best, w
hilst the lowest strength steel gave the worst performance. Crack netw
orks were formed in the specimens tested at nominal contact stresses o
f 1200 MPa and 1500 MPa. Isolated cracks were produced in the specimen
s tested at 1800 MPa.