The Influence of Pre-treatment on the Hardenability of the Plain Carbon Steel

On the hardenability of a plain carbon steel have already studied by many investigators for varied composition. But, there were little basic studied on the influence of pre-treatment with regard to hardenability of a medium carbon steel. In this paper, the present investigators studied the effect of pre-treatment methods on hardenability of S 40 C with carbon 0.41% and SUJ 5 with carbon 0.99% by means of hardness measurement and microscopic observation. The results obtained are as follows : 1) Hardenability of the plain carbon steel is improved by pre-treatment. 2) Hardenability of alloy steel which contain Cr, Mo and Mn, could scarcely be improved by pre-treatment as quench and temper. 3) In order to produce complete martensite by water-cooling, it is necessary to be exactly alike carbon concentration in austenite state.