热处理对电冶熔铸WC/钢复合材料中增强体转变规律的影响

Influence of heat treatment on transformation of reinforced body in WC / steel matrix composites by electroslag melting and casting

采用复合电冶熔铸技术,制备了以WC颗粒为增强体,5Cr Ni Mo模具钢为基体的WC/钢复合材料,WC颗粒含量为45wt%。采用金相显微镜、扫描电子显微镜、能谱仪、电子背散射衍射仪和X射线衍射分析仪研究了复合材料中WC的形态和退火、锻造、淬火与回火处理对WC增强体转变的影响。结果表明,WC/钢复合材料中以三角形或矩形的WC为主;通过退火和锻造处理,碳化物溶解,共晶组织碎化;淬火加热温度升高,碳化物溶解加速,基体上分布大量细小的二次碳化物,共晶碳化物变化不明显;回火温度提高,碳化物分布更加均匀化,颗粒圆整性增强,碳化物聚集现象减少。存在的碳化物类型主要为WC颗粒、较大的Fe3W3C颗粒、Fe3W3C或M7C3枝晶状碳化物、弥散分布的Fe3W3C或M23C6二次碳化物。

WC/steel matrix composites with WC particles as reinforced body and 5CrNiMo steel as matrix, were prepared by electroslag melting and casting technology. The content of WC was 45% in mass fraction. The morphology of WC in composites and the influence of annealing, forging, quenching and tempering on transformation of WC particles were investigated by OM, TEM, EDS, EBSD and XRD. The results show that WC particles in WC/steel matrix composites are in triangle or rectangle shape. After annealing and forging, the carbides dissolve, and eutectic structure is fragmented. With the increase of quenching temperature, the carbides dissolve quickly, and there are a large number of fine secondary carbides distributed on the substrate, and the eutectic carbides change not obviously. With the increase of tempering temperature, the carbides distribute more uniformly, the particle roundness is enhanced, and the phenomenon of carbides aggregation decreases. The type of the carbides are mainly WC particles, large particles of Fe3W3C, dendritic carbides of Fe3W3C or M7C3 , and secondary carbides of FezW3C or M23C6 as distributed dispersively.