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Failure Mechanisms in Automotive Exhaust Decouplers
Technical Paper
2004-01-0858
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
Automotive exhaust decouplers (flexible couplings) are a critical component that must remain leak free in order to meet extended warranty and pollution control requirements. The key component of a decoupler is the bellows, which allows easier fit-up during exhaust system assembly and absorbs vibration during service. This bellows is most often constructed of austenitic stainless steel. Though known for improved corrosion resistance, there are many possible corrosion related failure mechanisms for stainless steels. Nineteen decouplers, taken from standard endurance track tests and from normal highway use, have been destructively examined in order to document which failure mechanisms may cause premature failure and compare the performance of various component materials of construction. As a result of exposure to road salt in track tests and normal winter driving conditions, the decoupler bellows have been found to fail by stress corrosion cracking (SCC), pitting, crevice corrosion, hot salt attack, molten salt attack, accelerated oxidation and fatigue or corrosion-fatigue. Failure analysis results were correlated to laboratory testing results. Also the performance of stainless steel decoupler bellows were compared to units fabricated from more corrosion resistant high nickel alloys.
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Authors
Citation
Crum, J., Eisinger, N., and Parsons, R., "Failure Mechanisms in Automotive Exhaust Decouplers," SAE Technical Paper 2004-01-0858, 2004, https://doi.org/10.4271/2004-01-0858.Also In
Fatigue Research and Applications, and Fatigue Analysis and Creative Problem Solving
Number: SP-1839; Published: 2004-03-08
Number: SP-1839; Published: 2004-03-08
References
- Conway D. “Cutting Emissions With Metal Bellows” Machine Design August 24 1995
- Seltveit A. Flood H. Acta Chem. Scand. 12 5 1036 1958
- Michels H. T. “Corrosion Performance of Heat-Resisting Alloys in Automobile Exhausts” Metals Engineering Quarterly August 1974
- Chart J. E. Michels H. T. “Corrosion Performance of Austenitic Alloys in Automobile Exhaust Environments” Journal of Engineering Materials and Technology Transactions of the ASME July 1977
- ASTM Standard Practice A262-01 Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels
- Crum J. R. Smith G. D. Flower H. L. “Flexible Exhaust Coupling Alloy” Advanced Materials and Processes January 1998
- Bologna D. J. “Materials for Exhaust Systems” Annual Material Show & Conference American Society for Metals Cleveland Convention Center Cleveland, Ohio October 28 1976
- Crum J. R. Smith G. D. Flower H. L. “Resistance of Automobile Exhaust Flexible Coupling Alloys to Hot Salt Attack, Stress Corrosion Cracking and High Temperature Embrittlement” Paper No. 1999-01-0372 , SAE International Congress and Exposition Detroit, Michigan March 1-4 1999
- McFarlen W. T. “Corrosion and Processing Problems on Stainless Steel Bellows” SAMPE Journal August September October 1974
- “Glossary of Corrosion-Related Terms” Second NACE International March 1995