论文部分内容阅读
在实验室条件下采用立式连铸的方法连铸φ100 mm M2钢,在扫描电镜下观察分析其碳化物的分布、形貌、尺寸和类型,研究了析出碳化物的演变规律,并对其在液相区、固-液两相区和固相区的析出规律进行了热力学计算。结果表明:φ100 mm M2钢连铸坯碳化物呈网状分布,网状碳化物的厚度从铸坯边部的1.5μm增大到中心的30μm,增大约20倍。碳化物形貌包括:块状、片层状和棒状,其中块状碳化物为VC,而片层状和棒状碳化物为M_2C。在液相和固-液两相区δ铁素体析出过程中,各种碳化物均不具备析出的热力学条件;在固-液两相区中γ奥氏体转变过程中,W_2C在1504 K具有析出的热力学条件;当温度降到固相线以下时,碳化物的析出顺序为VC>Mo_2C>W_2C,其析出温度分别为1475 K、549 K和333 K。
The cast-in continuous casting method was used to cast φ100 mm M2 steel under laboratory conditions. The distribution, morphology, size and type of carbides were observed and analyzed by scanning electron microscopy. The evolution of precipitated carbides was studied, In the liquid region, solid-liquid two-phase region and the precipitation law of the solid-phase region was calculated thermodynamically. The results show that the carbides of φ100 mm M2 continuous casting billets are distributed in the shape of mesh. The thickness of the network carbides increases from 1.5μm to 30μm in the edge of the slab, increasing about 20 times. Carbide morphology includes: massive, lamellar and rod-shaped, wherein the massive carbides VC, and lamellar and rod-shaped carbide M_2C. During the precipitation of δ-ferrite in the liquid and solid-liquid two-phase zones, none of the carbides exhibited any precipitation thermodynamic conditions. During the γ-austenite transformation in the solid-liquid two-phase zone, With the precipitation of thermodynamic conditions; when the temperature dropped below the solidus, carbide precipitation sequence VC> Mo_2C> W_2C, the precipitation temperature was 1475 K, 549 K and 333 K.