等温淬火对含Sn蠕墨铸铁组织及抗热疲劳性能的影响

Influence of Austempering on the Structure and Thermal Fatigue Resistance of Vermicular Graphite Cast Iron with Sn

研究了不同等温淬火温度（270℃、320℃、370℃、420℃）和时间（0.5 h、1.5 h、2.5 h、3.5 h）对汽车制动鼓用含Sn蠕墨铸铁抗热疲劳性能的影响。试样850℃×0.5 h奥氏体化后,进行等温淬火和热疲劳试验。淬火后的组织分析表明,蠕铁基体组织为奥铁体,石墨的数量和形态无明显变化。等温淬火温度和时间能够影响蠕铁抗热疲劳性能,在20~600℃循环条件下,270℃×0.5 h处理后的蠕铁试样的裂纹扩展增长量最短,长度为0.84 mm,抗热疲劳性能最好。

The influence ofaustempering temperature（270℃, 320℃, 370℃, 420℃） and time（0.5 h, 1.5 h, 2.5 h, 3.5 h） on the thermal fatigue resistance of vermicular graphite cast iron with Sn was investigated. After austenitized at 850℃×0.5 h, the specimen were austempered with different processes. The analyzing results of austempered samples show that the matrix was ausferrite. The quantity and morphology of graphite were not changed under each condition. The thermal fatigue resistance ofvermicular graphite iron austempered at 270℃ ×0.5 h is the best, and the crack length is the minimum 0.84 mm under thermal cycles condition of 20-600℃.