This paper deals with the influence of Si, Mn, W, V and Mo upon the quench hardening of Steel. Specimens were quenched at 750°, 800°, 850°, 900°, and 950°C in water and oil. The hardness was measured by means of a Vickers' Hardness Tester, at every distance of 1mm. apart along a diameter on a section which was ground off 5mm from the surface. By a differential dilatometer, the influence on the transformation point was measured. The micro-structure was also examined. From the hardness distribution on the sectional surface, the following conclusions are deduced:
Si increases the quench-hardening effect of Steel, and is available for hardening throughout the range from edge to center at a higher quenching temperature. but in the vicinity of 800°C. the effect is less than plain carbon steel.
Mn makes, therefore, quench-hardening of steel easy even at a low quenching temperature, the more manganese causes the greater quench-hardening effect. At a higher quenching temperature and with further increase of Mn, however, the hardness distribution at the edge of specimen indicates a lower value owing to retained austenite.
W increases the effect of hardening. At a low quenching temperature and with about 1·0% of W, there is little difference in hardness at the edge and center, when W content is increased to 1·5-2·0%, the edge ipdicates a hardened state for only 1-2mm in depth, but near the center it resembles plain carbon steel.
V helps to harden steel and causes little difference in hardness. The specimen containing V, may however, be queuched from 950°C in water or oil, whilst V has a less effect on the depth of hardening.
Mo. even if it is contained a little, affects the hardness markedly, and at a higher quenching temperature the hardness becomes lower than that at a lower quenching temperature.
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