Study of sensitization and different heating cycles on stainless steels used for automotive exhaust components

In order to achieve a reasonable lifetime of automotive exhaust components, a large number of high alloyed ferritic and austenitic stainless steels are used nowadays. It is a common concept that the lifetime of a component is directly related to the performance of steel against corrosion. The components are divided into different sections depending on their service temperatures. High temperature oxidation resistance is one of the properties which are required in different sections. The effect of material sensitization on corrosion resistance of stainless steels is well understood from the literature. Besides, sensitization materials in exhaust systems have to withstand different cyclic heating and cooling phases. The objective of this study was to develop a basic understanding that can determine the influence of different temperature treatments on stainless steels. A fundamental understanding on the interaction of sensitization and cyclic heat impacts are presented in the paper.