Application of Laser Pulse Heating to Simulate Thermomechanical Damage at Gun Bore Surfaces*

Laser pulse heating (LPH) experiments were performed to provide insights into the thermomechanical damage effects that occur at the surface of coated and uncoated gun steel under cyclic, rapid heating and cooling. These effects include generation of a heat-affected zone (HAZ), severe plastic deformation, crack blunting, cavitation, fracture initiation, and generation of residual stresses. In addition, several of the deformation effects observed in the HAZ indicate superplasticity. The results are compared with data from surfaces exposed to several different firing conditions to provide a basis for analyzing the specific role of the various degradation mechanisms. Supporting information is provided from x-ray diffraction measurement of residual stresses in the steel heat-affected zones produced in a firing environment. The measured compressive stresses are explained using dilatometry data and are shown to be consistent with the observed damage processes.