滲炭窒化処理を施せる鋼材の磨耗現象について（第1報）

Abstract

Useing lubricant, the slide wearing tests, of carbonitrided steel were carried out. In the previous paper, the author reported in detail the carbo-nitriding of steel. The properties of hardened layer of carbo-nitrided steels remarkably differ with the composition of salt, condition of treatment and the composition of steels. Consequently, these factors have important influences upon wearing. Therefore, in order to determine the condition of wearing test sample, the author investigated on the hardness and internal stress of carbo-nitrided steels. The distribution of hardness of hardened layer is low mainly at the surface of steel,high at its center by influence of residual austenite by quenching. The effect of internal stress is slight, owing to lower quenching temperature than other methods.First, in order to determine the wearing condition, the wearing experiments were performed under the wide range on contact pressure, wearing veloclty, and wearing mechanism. In consequence, we determined constant condition of pressure was 15 kg/cm2, and of velocity was 3.4 m/sec, and then the experiment was carried out under these conditions.The results are as follows: The wearing amount of steel treated with carbo-hitriding are proportional to hardness of wearing surface; the greater the hardness is, the greater the wearing resistance becomes. Therefore, in order to get good wear resistance, the retained austenite of carbo-nitrided steel should be decreased as possible, for example, by means of proper selection of quenching temperature or tempering temperature, that is we could affirm that,it makes the wearing resistance to be good,to make residual austenite decrease in the heat treatment or to temper properly after quenching.Moreover, the author tested the worn surface by electron microscope, and recognized the clear difference between bright wearing and fused wearing and discussed the mechanism of wearing.