Product Code: ICA12_1909

Study on Temperature Dependence of Recoil Pressure Near the Boiling Temperature - Towards Better Modeling and Simulation
Authors:
Koji Hirano, Instrument & Control R&D Div., Process Technology Center, Technical Development Bureau, Nippon Steel Corporation; Futtsu-City, Chiba Japan
Remy Fabbro, PIMM Laboratory, CNRS-Arts et Métiers ParisTech; Paris France
Maryse Muller, PIMM Laboratory, CNRS-Arts et Métiers ParisTech; Paris France
Presented at ICALEO 2012

Nowadays it is widely accepted that recoil pressure is an important driving force of molten material in various laser material processing. However, we do not fully understand the physical processes that occur around the liquid-gas interface during evaporation. Consequently, temperature dependence of the recoil pressure near the boiling temperature remains unclear, although this information is essential to perform numerical simulations of laser keyhole welding. In this study we experimentally estimated the temperature dependence of the recoil pressure of pure iron from combined measurements of melt surface deformation and melt surface temperature. Our results provide the first experimental evidence that the recoil pressure can drive molten material only when the surface temperature exceeds the boiling temperature. This result indicates that a proper consideration of the ambient atmospheric pressure is indispensable to analyze hydrodynamics of molten material either analytically or numerically.