Condensate Corrosion Behavior of Stainless Steels for Automotive Mufflers

One oxidation-condensate immersion cyclic method was used to simulate muffler inter- nal service environment under the long-distance driving conditions. The corrosion behavior of type 409, 429, 436, 439 and 441 stainless steels was investigated in the condensate solutions. The results show that the oxidation/corrosion product films on the surfaces of these five steels are mainly com- posed of Cr2O3 and Fe2O3. The alloying elements Cr and Mo play the most important role in the re- sistance of product films and charge transfer processes on steel surfaces. Pit depth decreases in or- der of 409, 439, 441, 429 and 436, but there is small depth difference between 439 and 441 as well as 429 and 436. Moreover, these five stainless steels show good pit resistance in the simulated pro- cesses of long-distance driving trips.