Fe-Cr-B/42CrMo复合轧辊界面组织研究

Study on Interface Microstructure of Fe-Cr-B/42CrMo Composite Roll

采用电渣结晶器熔铸包覆高碳中锰Fe-Cr-B合金熔液与电磁感应预热42CrMo低合金钢辊芯相结合的固-液复合材料制备方法制备了高碳中锰Fe-Cr-B/42CrMo复合轧辊。运用OM、SEM、EDS、XRD研究了铸态下复合轧辊复合界面的显微组织特征,运用洛氏硬度计测试了复合界面两侧的硬度。结果表明:复合界面由极细的层片状珠光体组成;界面附近包覆层一侧主要由共晶组织和一种细小、致密的蜂窝状组织组成。其中,共晶硼化物为M2B,蜂窝状组织的硬质相为M3(C,B)碳硼化物;界面附近辊芯一侧主要由大量的细层片状珠光体、少量的块状铁素体和网状晶界碳化物组成。复合界面的铸态显微组织特征与其形成过程中两侧合金元素的相互扩散密切相关。其中,C、Mn、Cr、Mo和B从包覆层一侧向辊芯一侧进行了扩散,而Fe元素则由辊芯一侧向包覆层一侧进行了扩散。

High carbon and medium manganese Fe-Cr-B/42 CrMo composite rolls were prepared via pouring high carbon and medium manganese Fe-Cr-B alloy melt into the electroslag remelting mold to combine with a forged 42 CrMo low alloy steel roll core inside preheated to 920-930 ℃ by electromagnetic induction device around the mold. The 42 CrMo roll core needed to be preheated to about 750 ℃ in a heat treatment furnace before it was moved into the electroslag remelting mold. OM, SEM, EDS and XRD were used to study the microstructural characteristics of the composite interface of as-cast composite rolls. Rockwell hardness tester was used to test the hardness of both sides of the composite interface. The results show that the composite interface is composed of very fine lamellar pearlite, and the cladding layer near the interface is mainly composed of eutectic structure and a fine, compact honeycomb structure, in which the eutectic boride is M2 B, the hard phase of honeycomb structure is M3(C, B) carbon boride, and the roll core side near the interface is mainly composed of a large amount of fine lamellar pearlite, a small amount of massive ferrite and network grain boundary carbide. The as-cast microstructures of the composite interface are closely related to the diffusion of alloy elements on both sides during the forming process. Among them, C, Mn, Cr, Mo and B diffuse from one side of the cladding layer to the one side of the roll core, while Fe diffuses from one side of the roll core to the other side of the cladding layer.