EFFECT OF QUENCHING PARAMETERS ON MATERIAL CHARACTERISTICS OF SPECIMEN- AN OVERVIEW

In metallurgical industries, one the most important process is the quenching of metals which consists of raising steel temperature until austenitizing temperature and cooling rapidly to avoid undesirable internal microstructure as well as to ensure uniform mechanical properties. Numerous variables in the quenching process alone govern the ability of a part to meet distortion requirements among which Selection of Quenching media, Quench tank design, Quench agitation system, Bath temperature plays an important role which has been discussed in this article. Water due to too fast cooling produce more amount of martensite which results in hardened part. Oil due its phase transformation during quenching causes a variation in heat transfer rates hence leading to distortion. Air/gas does not have this problem and it has proven itself as environment friendly. In quench tank design draft tube impellers and directional flow baffles with improved structure gives better results. Use of quench agitation system improves the uniformity of cooling due to creation of turbulence in quench zone. . Increase in bath temperature decreases cooling rates and vice-versa. The use of CFD (Computational Fluid Dynamics) has proven itself as a powerful engineering analysis tool to reduce distortion, improve yield and to improve "first-time" quality. Due to use of CFD simulation tool fatigue caused to heat treat engineer has been greatly reduced and hence there is no necessity of experimental investigation for the improvement of existing quench system. In this review paper emphasis has been given to focus on various parameters which affect the uniformity of quenching process and use of CFD as a powerful tool to optimise the parameters so as to get better results