The alloys 625,31,33 and in some tests the newly developed alloy 626Si have been investigated with respect to their mechanical properties and their corrosion resistance against alkali salts containing chlorides at temperatures of 550°C, 650°C, 700°C and 750°C. Concerning strength in the sensitized condition, all alloys are suitable as decoupler materials. The mechanical properties of alloys 625, 626Si and probably 31 indicate adequate manufacturing possibilities of bellows. All alloys investigated suffer accelerated corrosion in the presence of alkali salt containing chlorides at temperatures ranging from 550°C to 750°C. At 750°C alloy 626Si shows the lowest corrosion rate. At 75O°C, 700°C and 650°C no difference between the solution annealed and the sensitized specimens was found. At 550°C, however, the corrosion rate of the alloys 625 and 33 increased significantly, when the material was sensitized prior to
corrosion testing. Alloy 31 does not suffer significant corrosion attack at 550°C both in the solution annealed and in the sensitized condition, thus making it a potential cost effective alternative to the more expensive alloy 625 for decoupler applications. Keywords: corrosion, sensitization, alloy 625, alloy 33, alloy 31, alloy 626Si, decoupler, automotive exhaust system