高碳铬钼钢贝氏体碳化物形貌及其形成机理

 取9Cr2Mo钢和GCr15钢，奥氏体化后进行中温等温转变，采用金相显微镜和QUANTA-400扫描电子显微镜研究贝氏体碳化物的形貌及其形成机理。结果表明，9Cr2Mo钢和GCr15钢的上贝氏体组织呈羽毛状，上贝氏体碳化物呈长短不一的薄片状或短棒状，分布在铁素体亚片条或亚单元之间，其排列与贝氏体铁素体片条轴向大体上平行分布；下贝氏体组织呈竹叶状或针状，下贝氏体碳化物呈细片状或纤维状等形状，分布在铁素体片中间，大多数与片条的主轴方向交角排列，但角度不等。钢中贝氏体碳化物在γ/α相界面上形核，向奥氏体中和铁素体亚单元间长大，是碳原子沿着相界面扩散的过程。

Morphology and Formation Mechanism of Bainite Carbide of High Carbon Chromium-Molybdenum Steel

The morphology and formation mechanism of Bainite carbide of 9Cr2Mo Steel and GCr15 steel were studied by metallographic microscope and QUANTA-400 electronic microscope after they were austenitized and then quenched at moderate temperature. The results show that upper bainite of 9Cr2Mo Steel and GCr15 steel is feathery and the upper bainite carbide is lamellar or claviform. The upper bainite carbide distributes between the subunits of bainite ferrites by and large parallelly to the axis of bainite ferrites. Lower bainite of 9Cr2Mo Steel and GCr15 steel is in bamboo leaf shape and the lower bainite carbide is in shred or fibre shape. The lower bainite carbide distributes between the bainite ferrites, furthermore, the angles between lower bainite carbonide and the principal axis of the lower bainite ferrites are unequal. Bainitie carbide nucleates at the phase interface of γ/αand grows towards austenite and the subunits of bainite ferrites, which is a diffusion transformation of carbon atom along the phase interface of γ/.