Abstract
Influences of microstructures on the wear resistance of high C-5%Cr-V steels are studied using a two-cylinder type wear test machine. Under the test conditions of low Hertz stress (100kgf/mm2)-high slip ratio (20%) and high Hertz stress (150200kgf/mm2)-low slip ratio (9%), the main results obtained are as follows.
(1) The initial wear rate decreases with C content, which increases primary carbides and spheroidized carbides. However, the steady state wear rate is increased by pit-like flakings which often occur in the primary carbides.
(2) The initial and steady state wear rates tend to decrease with the increase in V content up to the amount which makes the ratio of V content to C content, V/C, larger than 1. This decrease of wear rate closely relates to the fine precipitation of MC type carbides and the increase in the fraction of spheroidized carbides.
(3) In the case of the steels having V/C of less than 1, the steady state wear rate increases with the increase in the spheroidized carbides and the retained austenite.
Under the test condition of high Hertz stress and low slip ratio, the significant increase in wear loss is obtained in the steel having V/C of less than 1. It is indicated that the increase in wear loss is caused by the flaking which results from the nucleation, growth and coalescence of voids from the spheroidized carbides larger thab 1μm.
