Studies of High Power CO₂ Gas Laser as a Heat Source (Report 3)

Heat Conduction in Laser Heating

Abstract

Generalized heat onduction theory for a surface heat source, where the source moved at a constant speed, its intensity distribution was non-uniform and its power waveform was not constant, was developed, and temperature distributions in laser heating were discussed on the basis of this thenrv.
Conclusions obtained may be summerized as follows:
(1) Transient temperature distributions which were computed using measured energy distribution and waveform were in good agreement with the results obtained from micro-examinations observing the fusion line and temperature measurements.
(2) When the actual focused laser beam, having a Gaussian distribution, was approximated by a circular or ideal point sources, the deviation from the actual temperature distribution increased with increasing the traveling velocity of the source.
(3) In the case of AISI 304 stain ess steel (SUS 27), it was quite well to neglect an effect of the pulsive laser waveform on the tern perature rise except for at location in the vicinity of the surface, and then the ac excited laser beam may be regarded as an equivalent constant power source. However, for metal with high thermal diffusivity such as aluminium, the effect was large even at the bottom surface of the sheet about 0.3 mm in thickness.