20钢复合渗铬中的相变  

PHASE TRANSFORMATIONS DURING COMPOSITE- CHROMIZATION OF STEEL 20

作　　者：伍翠兰[1] 罗承萍[1] 邹敢锋[1] 

机构地区：[1]华南理工大学机械工程学院,广州510641

出　　处：《金属学报》2004年第10期1074-1078,共5页Acta Metallurgica Sinica

基　　金：教育部高等学校博士学科点专项科研基金项目20030561001;国家自然科学基金项目50371028资助

摘　　要：应用金相、X射线衍射和微区成分分析研究了20钢经离子氮化后在不同温度渗铬(复合渗铬)所得渗铬层的显微组织及其生成机制.不同温度复合渗铬层的表面层均由CrN(fcc),β-Cr2N(hcp)和α-(Cr,Fe)(bcc)组成,其中α-(Cr,Fe)的含量随渗铬温度提高而减少.在复合渗铬过程中,原先的氮化白亮层发生扩散反应相变,生成复合渗铬白亮层,而扩散层中的相变主要是析出/共析转变,生成γ’氮化物析出带和/或一种类似珠光体的(α+γ’)共析反应带.The morphology and formation mechanism of the microstructure of the composite ion-nitrided plus chromized layers obtained at various chromization temperatures in a plain low-carbon steel (steel 20) were investigated using metallography, X-ray diffraction and microanalysis. It was found that the surface zone of the composite-chromized layers obtained at various temperatures was composed of the phases CrN (fcc), beta-Cr2N (hcp) and alpha-(Cr, Fe) (bcc), in which the fraction of a-(Cr, Fe) decreased with increasing the chromization temperature. During chromization of the nitrided layer, the diffusion-controlled reaction transformation occurred within the white (compound) layer of the former nitrided layer, forming a white composite-chromized layer. Meanwhile, the precipitation/eutectoid reaction took place in the transition (diffusion) zone of the nitrided layer during air cooling from a chromization temperature at or above 580 V, resulting in the formation of a gamma' nitride precipitate zone and/or an (alpha+gamma') eutectoid zone similar to the pearlitic structure.

关 键 词：20钢 复合渗铬 相变 渗铬层 渗氮层 

分 类 号：TG142[一般工业技术—材料科学与工程] TG156.8[金属学及工艺—金属材料]