钢的多元渗硼层组织结构的变异

以４５钢、ＧＣｒ１５钢为基体材料，先渗硼，后钒化，获得硼化物和碳化钒的多元渗硼层。采用金相显微镜，Ｘ－射线衍射仪和电子探针，分析测定了覆层的组织结构和成分分布。结果表明，渗硼试样长时钒化，Ｃ、Ｂ、Ｖ和Ｃｒ等元素在覆层中重新分布，硼化物逐渐蜕化，蜕变程度取决于钒化温度和时间，以及基体的化学成分。硼化后钒化过程中，表面与奥氏体之间存在碳活度差，碳原子向表面上坡扩散，ＶＣ覆层向外生长。实验表明，获得连续的多元渗硼层是可能的。

MICROSTRUCTURAL CHANGES DURING VANADIZING OF MULTICOMPONENT BORIDING COATINGS OF STEELS

An optical microscope, the x-ray diffractometer and the JXA-8800M EPMA were used to analyse and determine the microstructure and composition distribution in multicomponent boriding coatings which are formed on 45 and GCr15 steel. Results show that C, B, V and Cr etc are redistributed in the coated layers and borides can be gradually changed into austenite during long time vanadizing. The degree of change of borides is dependent on temperature and time for vanadizing and composition of substrate. As difference of carbon activity between surface and austenite, carbon atoms can diffuse to up hill V 8C 7 coating can grow out. The continuous coating can be obtained.