Ultra-Fine Grain Steel Produced by Carbide Dispersion Carburizing Process

C-D渗碳--获得弥散碳化物颗粒的渗碳处理--已在几种钢上进行了试验，以生产超细晶粒钢。主要研究结果如下：1.合金元素在C-D钢中的作用钒具有较大的溶解度，是实现碳化物细小弥散的最有利元素，而钒碳化物对铁基的溶解度较小。铬、钼、钨、钴是提高二次硬化和耐磨性的有效元素。在这些初步试验的基础上，确定了钢的成分为：V 7%、Cr 2%、Mo 4%、W 3%、Co5%。C-D钢的力学性能试验结果如下：(1)抗拉强度；(2)维氏硬度；950-1000；(3)耐磨性优于市售高速钢；(4)弯曲强度；3.4 Gpa。这些值表明，C-D钢在强度和塑性方面都具有优越的性能，这主要是由于其超细晶组织所致。实际应用C-D钢有望用于制造薄壁零件，如精细刀具、精细钻头、用于网点印刷的销钉等。适用性审查将从技术和经济两个方面进行。

The C-D carburizing-- carburizing treatment for obtaining dispersed carbide particles -- has been tried on several kinds of steel to produce ultra-fine grain steels. The results obtained are summarized as follows :1. Function of Alloying Elements in C-D Steel Vanadium is the most profitable element to realize the fine dispersion of carbides, because it has a large solubility, while the V-carbide has a much less solubility to the Fe-matrix. Cr, Mo, W and Co are effective to improve the secondary hardening and abrasive resistance. On the basis of these preliminary experiments, the composition of steel was chosen as 7%V, 2%Cr, 4%Mo, 3%W and 5%Co.2. Mechanical Properties of C-D Steel The results of mechanical tests on the above-mentioned steel are as follows; (1) tensile strength; 1.8GPa, (2) Vickers hardness;950- 1000, (3) abrasion resistance is better then the commercial high speed steel, and (4) bending strength; 3.4 GPa. These values indicate that the,C-D steel is superior in both the strength and ductility, which is mainly due to the ultra-fine grain structure.3. Practical Use The C-D steel is expected to be useful to thin parts,i.e.,fine cutters, fine drills, pins for dot-printing and so on. The examination of applicability will be carried on from the both sides of technical and economical points.