The non-destructive heat treatment of surface by laser is known to be possible only when a set of conditions is fulfilled under the laser heating of surface. The main conditions are the following: 1) the radiation parameters should be chosen so that the destruction threshold is not exceeded: 2) the material heating should occur impetuously enough so that the material have no time for transition into liquid state up to the temperature of destruction (in fact to the boilging temperature). The basis for the determination of these conditions is the corresponding boundary-value heat problem which seems to have been well investigated. However very large range of temperature (from normal to the boiling temperature). An account of distribution of stimulating radiation in material, and a high power of radiation result in the problem will be essentially nonlinear on temperature and will obtain a adequately complex inhomogeneity ("optical" nonlinearity). Since lasers are usually used in high technologies, the account of these circumstances allows to correctly determine the destruction threshold, the relaxation time and to predict adequately the dynamics of temperature both on the surface and in the volume. At present we have analyzed the problem of dependence of the material parameters on temperature, the problem of radiation behaviour in material under the high power radiation. It has been performed the analysis of the correlation of relaxation times and time of liquid phase formation. The heat problem accounting all these factors has been formulated and has partially solved.
Publication Source: Trends in NDE Science & Technology; Proceedings of the 14th World Conference on Non-Destructive Testing, New Delhi, 8-13 December 1996.Vol. 3, pages 1489 - 1492 Publisher:Ashgate Publishing Company
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