金属模具表面稀土催化共晶渗硼组织及其性能

Microstructure and Properties of Metal Mold Surface by Rare Earth Catalytic Eutectic Boronizing

为了提高模具表面的磨损性能,采用稀土催化共晶渗硼工艺对45钢模具表面进行了处理,研究了不同稀土加入量对共晶渗硼层组织、渗硼层厚度、硬度梯度及其磨损性能的影响规律,分析了稀土活化催渗机理和材料磨损机制。结果表明:共晶渗硼层组织为硼化物与γ铁的混合物;稀土加入量为9%时共晶渗硼效果最佳,渗硼层厚度比传统固体渗硼层增加近1倍,渗硼层硬度显著提高且硬度梯度减小;稀土元素具有活化催渗硼原子、促进硬质相形成以及细化晶粒、强化晶界的作用;经稀土催化渗硼的试验材料两体磨损性能比传统固体渗硼材料提高约18%,且耐磨行程提高近12倍;试验材料磨损失效主要以显微切削为主;渗硼层厚度增大、硬度提高、硬度梯度减小是稀土催化共晶渗硼材料磨损性能得以提高的主要原因。

The rare earth catalytic eutectic boronizing is used in treating the surface of 45 steel mould to improve the wear resistance of the mould surface. The influence of rare earth addition on microstructure, thickness, hardness gradient and wear resistance of the eutectic boride layer is studied. The action of activity and catalysis of the rare earth and the wear mechanism of the eutectic boride layer are analyzed. The results show that the microstructure of eutectic boride layer consists of boride and y-Fe. When the addition of rare earth is 9~, the best effect of eutectic boronizing is achieved, in the sense that the thickness of eutectic boride layer is 1 times thinker than the boride layer obtained by the traditional solid boronizing, the hardness of the boride layer increases remarkably and the hardness gradient decreases. The rare earth has the action of activity and catalysis, promotes formation of hard phase, and effectively fines the microstructure of eutectic boronizing layer. The rare earth catalytic eutectic boronizing improves the wear resistance of boride layer by 18% and increases wear distance 12 times, compared with the traditional solid boronizing. The micro-cutting is the main wear mechanisms. Increasing the thickness of eutectic boride layer, improving the hardness, and decreasing the hardness gradient are the main factors to increase material wear resistance.