軸受鋼の研究(III)

Abstract

There are two kinds in the steel-making process of the ball bearing steels, namely, small acid open-hearth and basic electric-arc process.The former is adopted mostly in SKF Hofors Bruks, and the latter is the process which is used mostly in Japan and U.S.A.Therefore, the austenitizing behaviour of the above kind ball-bearing steels, made in Japanese steel maker and tubings of SKF bali bearing steel is studied and reported in this paper.The steels, made by the acid open hearth and the basic electric arc process, have the different quenching-sensibility. According to this sensibility, the difference of change in the hardness and the mechanical property is barely, but the ease, with which the cementite goes in solution in the austenitizing state, is very different by the above two kind of process.Namely, the cemente in the electric arc furnace steel goes in solution easily, but it does not go in solution easily under 850°C temperature and goes in solution easily and rapidly above 850°C temperature in the open hearth furnace steel.Secondly, although there are many non-metallic inclusions in SKF tubings of ball-bearing steels, these steels are stable in the austenitizing state, and the quenching sensibility of this steels is dull.This relates to the solution speed in the cementite, and the solution of it is stable comparatively from 800°C to 880°C temperature.