How Powder Metallurgy Exhaust System Flanges Can Respond to Recent Commercial, Market and Legislative Pressures 960384
Virtually all automotive systems are subject to intense commercial, market and legislative pressures to evolve in new directions. The exhaust system is no exception. The relentless drive to: reduce costs, to extend warranty and service life, to respond to customer cosmetic preference for bright metal under hood combined with emission legislation demanding zero leakage stretch the imagination and resourcefulness of the industry. Powder metallurgy (P/M) has a role to play in this regard. The complex and accurate net shape capability and material versatility of P/M provides an attractive combination for several components especially flanges. A hindrance, however, is lack of a materials property database relating to the special properties required for service. High burnt gas temperatures in exhaust systems produce internal corrosion oxidation attack, and stress relaxation of joints while road salt attacks the external surfaces.
To address this lack of data, a program was undertaken to test both currently used wrought materials and prospective P/M materials for functional properties. In some cases a test method had to be developed prior to material testing. This paper reports the test methods and resulting material properties to assist with future P/M growth in this area.