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Due to more stringent regulatory restrictions, the requirements for exhaust system components have become more demanding. The flanges, in particular, must provide tight sealing capability, and they must maintain this sealing capability for countless numbers of thermal cycles. The tough creep and oxidation criteria, coupled with the increased corrosion resistance required to meet the long term durability and weld integrity is moving exhaust system components toward Stainless Steel materials. The competitive cost benefits offered by the Powder Metal forming technology for fabricating Stainless steel exhaust system flanges has driven extensive study and testing of a variety of P/M exhaust flange applications.

Property test data shows 434 stainless steel material, with and without nickel additions, to be a desirable material for exhaust system component applications. The material provides a good balance of corrosion and oxidation resistance, impact strength, and tensile strength compared to other 400 series stainless steel powder metal (P/M) materials. Addition of nickel to standard 434 greatly improves many physical properties with a slight increase in cost. Parts with densities between 7.2 and 7.5 g/cc offer the best combination of properties versus process economics. The processing costs to achieve high densities are minimized when the parts are sintered at temperatures at or above 2400°F, thus eliminating the need for a secondary operation such as coining or heat treating.