タフトライドしたSKD11の表面の耐摩耗性

抄録

It has been reported in the past that the tufftriding treatment improves the wear resistance of the iron and steel. For this reason, the tufftrided alloy tool steel is being widely used as the dies material for plastic working. However, its wear characteristics are hardly clarified.
In the present study, the wear characteristics of the alloy tool steel (SKD 11) treated in various tufftriding time are investigated to find the most suitable tufftriding time.
The following conclusions have been obtained.
(1) The compound layer composed of two sub-layers is formed at the surface of specimen by the tufftriding treatment. The composition of the outside sub-layer is mainly the nitride of Fe (Fe₃N, εFe₃N-Fe₂N) and that of the inside sub-layer is mainly the nitride of Cr (CrN, Cr₃N).
(2) The diffusion layer is formed under the compound layer, and both nitride and carbide are observed at the grain boundary in the diffusion layer.
(3) The hardness value of the outside compound layer is lower than those of the inside compound and diffusion layers, and the outside compound layer comes off easily by the dry wearing at the room temperature.
(4) The inside compound and diffusion layers contribute to the improvement of wear resistance, and the wear resistance is improved most when the specimen is tufftrided for about 12 hour.