铬钼钢贝氏体组织形貌及形成机理(英文)

Morphology and formation mechanism of bainite in chromium-molybdenum steel

将12CrMo、20CrMo、35CrMo和9CrMo钢在不同温度奥氏体化后,经中温等温转变,采用金相显微镜和QUANTA-400环境扫描电子显微镜观察了贝氏体的组织形貌,分析了其形成机理。结果表明,在低碳铬钼钢中形成无碳贝氏体;中碳铬钼钢的上贝氏体也是无碳贝氏体,下贝氏体中则有碳化物析出;而在高碳铬钼钢中,形成羽毛状的上贝氏体和竹叶状的下贝氏体。这表明含碳量对贝氏体的组织形貌有重要的影响。当贝氏体铁素体片条之间不能合并时,形成无碳贝氏体,随着含碳量的增加,当有碳化物析出时,就会形成羽毛状的上贝氏体或竹叶状的下贝氏体。

The morphology of bainite in 12CrMo,20CrMo,35CrMo and 9CrMo steel was observed using metallographic microscope and QUANTA-400 environmental scanning electron microscope after the samples were austenitized and then isothermally quenched at intermediate temperature zones respectively.The forming mechanism of bainite was investigated.The results show that massive or lamellar carbide-free bainite is obtained in the low carbon chromium-molybdenum steel,carbide-free upper bainite and lower bainite containing carbide are observed in the medium carbon chromium-molybdenum steel,while feather-shaped upper bainite and bamboo-leaf-shaped lower bainite form in the high carbon steel.It suggests a significant effect of carbon content on the morphology of bainite.It is considered that carbon-free bainite comes into being if the bainite ferrite laths can not combine together while with the the increase of carbon content,feather-shaped upper bainite and bamboo-leaf-shaped lower bainite will form when the carbide separates out.