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利用扫描电镜研究了中碳NiCrMo钢过热断口(石状断口)的微观形态。观察结果表明,过热的石状断口为沿晶塑坑断裂。过热断口上的MnS夹杂的形态及大小变化很大,在同一个石状颗粒的各个表面上可以表现大不相同。在断口上有时直接观察到MnS夹杂的魏氏析出特征,即硫化物夹杂以极为弥散的形式均匀地析出在高温奥氏体的{100}晶面上。对各种形态的硫化物夹杂可能的形成原因及其控制因素进行了讨论。
The microscopic morphology of the superheated fracture (stone fracture) of medium carbon NiCrMo steel was studied by scanning electron microscopy. The observation shows that the overheated stone fracture is along the crystal pit. The shape and size of the MnS inclusions on the overheated fracture vary greatly, and can vary widely on each surface of the same stone-shaped particle. The WeiShi precipitates of MnS inclusions are sometimes directly observed on the fracture surface. That is, the sulfide inclusions are uniformly precipitated on the {100} crystal plane of high-temperature austenite in an extremely dispersed form. The formation reason of various kinds of sulfide inclusions and its controlling factors are discussed.