Abstract: The thermal-fatigue behavior with 800 cycles of ambient-1 000℃ for 1. 5 mm cold-rolled sheet of 409,429 and 441 super ferrite stainless steels produced by pre-treaded metal-90 t K OBM S-VOD-LF-slab CC flow sheet for auto exhaust pipeline has been studied. Results show that the thermal-fatigue (crack length with 800 cycles- 1. 2mm) of steel 429 (/%: 0. 009C, 0. 86Si, 15. 3Cr, 0.47Nb) and steel 441 (/%: 0. 008C, 0.45Si, 17. 9Cr, 0. 39Nb, 0. 18Ti) is better than the thermal-fatigue (crack length with 800 cycles- 2. 0 mm) of steel 409 (/% : 0. 007C, 0. 40Si, 11. 2Cr, 0. 14Nb, 0.10Ti) ； during reversing ambient-1 000 °C heating-cooling process, the Fe atoms in weak region of steel are first oxidized to form oxides and peel off from base metal, led to form crack, and the formed Fe₂SiO₄ • Cr₂O₃ oxide films near crack prevent crack further developing.

摘要： 研究了预处理铁水-90 t K OBM S-VOD-LF-板坯CC流程生产的1.5 mm冷轧超纯铁素体不锈钢409、429和441板材室温-1 000℃800次循环的热疲劳性能。结果表明,429钢(/%:0.009C,0.86Si,15.3Cr,0.47Nb)和441钢(/%:0.008C,0.45Si,17.9Cr,0.39Nb,0.18Ti)的热疲劳(800次循环的裂纹长度1.2 mm)明显优于409钢(/%:0.007C,0.40Si,11.2Cr,0.14Nb,0.10Ti)的热疲劳(800次循环的裂纹长度2.0 mm);在室温-1 000℃的冷热交替过程中钢的薄弱部位Fe元素会首先形成氧化物并剥落,从而产生裂纹。裂纹附近表面形成Fe₂SiO₄·Cr₂O₃复合氧化膜,阻碍裂纹进一步扩展。