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Continuous Wave Fibre Laser Drilling of High Aspect Ratio Holes in Ni-Based Alloys
H.K. Sezer

Over the last 40 years the laser drilling of metallic alloys has been achieved by pulsed beams through percussion, trepanning (cutting), and helical processes. This paper reports a new laser drilling technique based on a continuous wave (CW) 1 kW single mode fibre laser. Through-holes of 160.0 to 190.0 mm diameters were drilled in 2 mm thick Ni-based superalloy plates. Zero tapered holes with a small recast layer (<15.0 mm) free from microcracks were demonstrated for drilling CMSX-4 single crystal and Haynes 230 superalloys. The drilling time was less than 20 ms per hole. A discussion is made on the drilling mechanism involved in the CW fibre laser drilling in comparison with pulsed beam drilling supported by computational fluid dynamic (CFD) modelling.

Keywords: Fibre laser, nickel alloy, Ni-based alloy, CMSX-4 single crystal superalloy, Haynes 230 superalloy, laser drilling, continuous wave (CW), taper, recast layer, computational fluid dynamic (CFD) modelling, aerospace

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