Contemporary Intensive Methods of Steel Hardening in Cold Fluids

Abstract

In the paper, the new intensive quenching technologies are discussed which are based on controlling the self-regulated thermal process (SRTP) which exists for a long time if any film boiling is absent. It is rather intensive until convection starts. Despite the intense process (Kn > 0.8), when the heat transfer coefficient and Biot number tend to infinity, there are several ways of controlling the surface temperature of steel components by varying the boiling temperature of the fluid. To eliminate any film boiling process and provide SRTP, the author of the paper explores the resonance effect, a thin surface insulating layer that covers the surface of machine components and electrical negative forces to control the double electrical layer that is responsible for destroying the film boiling mode. Based on SRTP control it is possible to delay the transformation austenite into martensite or even accelerate these transformations. The most important are possibilities to control surface temperature during the boiling process. All of this opens great opportunities for increasing significantly service life of machine components and tools. In the paper also the simplified method of cooling time calculation is proposed. It is based on the new principles concerning pure transient nucleate boiling taking place during the hardening steel in cold fluids. Since the paper simply explains everything, results of investigations will be widely used in the heat-treating industry.