• Seabra, Jorge
• Santos, H.
• Duarte, A.

Abstract

Ausferritic and mixed ausferritic plus tempered martensitic microstructures were produced, by the application of austempering heat treatments to a CuMn ductile iron, in order to evaluate the behaviour of these multi-phase microstructures under contact fatigue service. The mechanical properties of these microstructures were characterized, a set of heat treatments being selected to be applied on the contact fatigue trials. Contact fatigue tests were performed in a twin-disc machine, together with auxiliary techniques, such as video imaging for the contact surfaces observation and ferrographic analysis to study the wear particles released from the same surfaces. High contact pressures were used and artificial indentation defects were generated on the discs surfaces in order to accelerate the contact fatigue damage. Results from this work include the determination of a good correlation between the austempering temperature and the respective contact fatigue life, the identification of two methods to observe the fatigue damage progress with the number of cycles imposed, and finally the comparison between different grades of CuMn austempered ductile iron.

Topics

• microstructure
• surface
• phase
• fatigue
• defect
• iron