Key to the satisfactory performance of automotive exhaust couplings is adequate high temperature corrosion resistance. This is becoming especially critical as service life is being extended by government
legislation and as service temperatures are increasing due to the need for increased fuel efilciency and faster catalyst light-off. Currently
employed and candidate coupling alloys, including 409, 304, 316T1 and 321 stainless steels (SS) and alloys 600, 800, 864 and 625, are selectively evaluated for resistance to road salt spray corrosion, oxidation in air and engine exhaust gases and under cyclic burner rig conditions, These laboratory results are compared with alloy performance of couplings subjected to test track and field exposure.
Key Words: couplings, high temperature corrosion, cyclic oxidation, stress corrosion cracking, pitting, intergranular attack, alloy 409 (UN S40900), alloy 304 (UNS S30400), alloy 316Ti (UNS S31600), alloy 321 (UNS S32100), alloy 840, alloy 800 (UN N08800), alloy 803, alloy 864, alloy 825 (UNS N08825), alloy 625 (UNS N06625), alloy 600 (UNS
N06600), alloy 601 (UNS N06601)