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Calculation of temperature and heat flux in quenched cylinders for different wetting processes
Author(s) -
Loshkaroev † Vladimir E.,
Tensi Hans M.,
Gese Helmut,
Stich Anton
Publication year - 1994
Publication title -
steel research
Language(s) - English
Resource type - Journals
eISSN - 1869-344X
pISSN - 0177-4832
DOI - 10.1002/srin.199401182
Subject(s) - wetting , nucleate boiling , thermodynamics , quenching (fluorescence) , boiling , chemistry , heat transfer , heat flux , die (integrated circuit) , materials science , composite material , physics , optics , fluorescence , nanotechnology
The cooling of pieces being quenched in evapourable fluids is mainly determined by the process of wetting, which is defined as the sequence of the three known cooling stages film boiling, nucleate boiling and convective heat transfer. All these determine the properties of the finished product. The effect of different wetting processes and heat transfer coefficients on the time‐dependent distribution of temperature and heat flux in quenched cylinders was examined using numerical methods. Only transformation‐free quenching was considered. When the three cooling stages simultaneouly take place on the sample's surface the radial heat fluxes are superimposed by high axial heat fluxes, which could not be pointed out experimentally before. The consequences may be great axial differences of structure and hardness, especially for steels with low hardenability, as well as residual stresses. The axial temperature gradients can be reduced by producing high wetting velocities. An optimum wetting process involves a very fast breakdown of the vapour envelope on the whole surface of the quenched piece.