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Characterisation of Material Transformation during Cast Iron Brake Disc Bedding
Technical Paper
2006-01-3185
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
Cast iron brake discs are commonly used for road and race applications. The graphite flake arrangement of grey cast iron matches the high thermal conductivity requirements of brake discs, although with the brittleness characteristic of this material. Therefore the design of cast iron brake discs is a compromise between a thermally efficient design to reduce the operating temperature and a design generating a controlled tensile stress level to prevent crack failure, with as little mass penalty as possible.
The most critical failure mode on competition brake discs is catastrophic crack propagation in the early stages of service life. Dynamometer testing has shown that the initial bedding process greatly reduces the likelihood of catastrophic disc failure. This fact leads to the hypothesis that a heat treatment process occurs on the discs during bedding, increasing their crack resistance.
A visual microstructure analysis using conventional and scanning electron microscopy has revealed that the braking face temperature locally exceeds the critical phase transformation temperature during bedding. Moreover, a breakdown of pearlite occurs around graphite flakes, leading to a more ductile and crack resistant ferritic structure.
This paper finally investigates the compared influences of heat treatment and friction interface in the strengthening of the brake disc during bedding.
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Authors
Topic
Citation
Mace, G., Bowler, N., Goddard, G., and Morrey, D., "Characterisation of Material Transformation during Cast Iron Brake Disc Bedding," SAE Technical Paper 2006-01-3185, 2006, https://doi.org/10.4271/2006-01-3185.Also In
SAE 2006 Transactions Journal of Passenger Cars: Mechanical Systems
Number: V115-6; Published: 2007-03-30
Number: V115-6; Published: 2007-03-30
References
- Cast Iron Brake Discs - Current Position Chatterley T. C. SAE 1999-01-0140
- Effect of Brake Disc Surface Texture on Friction Behavior during Running-in Okamura T. Ono M. SAE 2004-01-2765
- Brake Disc Thermal Mapping System Honner M. New Technology Research Centre, University of West Bohemia 2005
- Data Handbook for Grey Cast Iron Fallon M, J The Casting Development Centre 1997
- Cast iron: Physical and engineering properties Angus H. T. Butterworths & Co 1976 2nd 256
- Modelling microstructural evolution and mechanical properties of austempered ductile iron Thomson R. C. James J. S. Putman D. C.
- Comparative study of fracture toughness of austempered ductile irons with upper and lower ausferrite microstructures Prasad Rao P. Putatunda S.K. Materials Science and Technology 14 1257 1265 1998