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Heat Transfer Characteristics of Laser Gas-assisted Drilling into Alumina Coated Carbon Steel Sheet
S.Z. Shuja and B.S. Yilbas

Laser gas-assisted drilling of holes into alumina coated carbon steel is considered and heat transfer characteristics and the skin friction at the wall surface are investigated for various gases. The hole wall is considered to be at the melting temperature of the coating material and carbon steel to resemble the drilling process in the simulations. Laser drilling experiments are carried out to demonstrate the thermal erosion in the close region of the coating and the base material interface. It is found that the presence of coating at the hole inlet increases the assisting gas temperature significantly in the vicinity of the coating. This, in turn, results in heat transfer from assisting gas to the hole wall while causing thermal erosion at the interface region between the alumina coating and the carbon steel. The skin friction changes for different assisting gases and helium results in the highest skin friction at the hole wall surface.

Keywords: Laser drilling, carbon steel, alumina, heat transfer, skin friction, thermal erosion, mathematical model

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