THE ROLE OF RECOIL PRESSURE IN ENERGY-BALANCE DURING LASER MATERIALS PROCESSING

A theoretical analysis of the energy balance in the laser-metal intera ction zone is carried out. The heat transfer due to the recoil-pressur e-induced melt flow is taken into consideration. It is shown that, for the absorbed laser intensities typical in welding and cutting, the re coil pressure induces high-velocity melt-flow ejection from the intera ction zone. This melt flow carries away from the interaction zone a si gnificant portion of the absorbed laser intensity (about 70-90% at low laser intensities); thus, convection-related terms can be ignored nei ther in calculations of the energy balance in the interaction zone nor in calculations of the thermal field in the vicinity of the weld pool or cutting front.