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One way to respect the Euro 5 depollution norm is the downsizing of the engine, which leads to more severe in-use operating conditions especially an increase of the exhaust gas temperature. Consequently, the hot part of the exhaust system, i.e., from manifold to the catalytic converter, could be subjected to maximal temperature up to 1000°C. Moreover, an improved durability and longer life guaranties are also required for such parts. In this context, a new ferritic stainless steel grade has been developed, named K44X (AISI 444, EN 1.4521), which fulfills these new specifications and that could be applied for both fabricated manifold and turbocharger shells. The K44X, with a chromium content of 19% (weight), an addition of 2% molybdenum and 0.6% of niobium, offers excellent high temperature properties like cyclic oxidation, creep and thermal fatigue resistance, a low thermal expansion coefficient.