In response to the automotive industry's need to find stronger, more oxidation resistant stainless alloys, a study was carried out to evaluate 12% Cr ferritic stainless steels alloyed with Al, Ti and Cb. An alloy with 1.2%Al, .3%Ti and .6%Cb was chosen to optimize oxidation resistance, processability, weldability, and creep or sag strength.
This ferritic composition known as 12SR possesses creep strength far superior to 409 due to solid solution strengthening with Cb. The Al and slightly higher Cr contents compared to 409 have increased the maximum service temperature with respect to oxidation by at least 55-83°C (100-150°F). Potential automotive applications include truck converters, sheet metal manifolds, and diesel particulate traps. By using the improved elevated temperature properties, weight savings may be realized.
