The strength ofthe Ti single-stabilized 409 stainless steel and the Ti–Nb dual-stabilized 409 stainless steels at 500, 600, 700, and 800 C, respectively, is shown in Figure 5. The tensile strength and 0.2% proofstrength ofall steels decrease with the increase of the temperature. In tensile strength, 409Ti–Nb stainless steels present small advantages. However, at all temperature, 0.2% proof strength is improved by Nb addition. The improvement in 0.2% proof strength is particularly remarkable at 600 C, especially for 409Ti– 0.30%Nb. 409Ti–0.15%Nb and 409Ti–0.30%Nb both show approximately 50–60MPa higher 0.2% proof strength than 409Ti at 500 and 600 C. 409Ti–0.30%Nb exhibits the highest 0.2% proof strength. However, there is not much difference between 409Ti–0.15%Nb and 409Ti–0.30%Nb in the temperature range from 700 to 800 C. Tensile strengths and 0.2% proof strengths of 409Ti–Nb stainless steels at 500 and 600 C can be up to 150 and 120MPa, respectively, which should be beneficial for the application at hightemperature section of the exhaust system manufactured by 409 ferritic stainless steel.Since the endurance is obviously correlated to the 0.2% proof strength at high temperature, the 409Ti–0.30%Nb exhibits logically the best fatigue resistance. 409Ti–Nb stainless steels exhibit approximately 15% higher fatigue limit than 409Ti stainless steel at 600 C, as shown in Figure 6. It can be seen that the fatigue strength of the dual stabilized steel increases about 20–40MPa comparing with the single stabilized 409 stainless steel.