Optimal quenched layer at the surface of steel parts

N. I. Kobasko:
OPTIMAL QUENCHED LAYER AT THE SURFACE OF STEEL PARTS

Proceedings of the 8th Seminar of the International Federation for Heat Treatment and Surface Engineering , IFHTSE 2001, Dubrovnik- Cavtat, Croatia, 12 – 14 September 2001.

ABSTRACT:
Intensive steel quenching is presented, the implementation of which produces a hard layer of optimal depth at the surface, and intermediate phases are formed in the core. The optimal hard layer corresponds to maximum residual stresses at the surface hardened. The formation of martensite in the conditions of high compressive stresses results in the additional strengthening of material. The mechanism of this phenomenon is explained. New intensive steel quenching technologies (IQ-2 and IQ-3) have been described, which essentially prolong the service life of hardened parts. The generalized formulas for the determination of the time of reaching maximum compressive stresses on the surface and length of nucleate boiling have been proposed. Concrete experimental facts are given which prove the presence of high residual compressive stresses at the surface of parts hardened and increase in their service life. It is emphasized that there is a sense to use widely new technologies in practice because they have a plenty of advantages, and the service life being prolonged by 2 or 3 times, the labor efficiency increases, and the technology itself is ecologically pure.


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