Product Code: ICAL08_310

Laser Drilling in Superalloy with 150~550Ns Pulse Train
Authors:
Xiaobing Zhang, beijing aeronautical manufacturing technology research institute; Beijing Peoples Republic of China
V.A. Serebrjakov, Institute for Laser Physics; St. Petersburg Russia
M.V. Volkov, Institute for Laser Physics; St. Petersburg Russia
Presented at ICALEO 2008

This paper introduces the principle and characteristics of an AO Q-switched YAG laser of 100-700ns single pulse duration working in pulse train mode which has been developed specially for making holes with thinner recast. The laser oscillator is composed by a low power AO Q-switched YAG laser of TEM00 mode as seed laser and two amplifiers for increasing its pulse energy and average power which are pumped by power supply unit in pulse mode. So the laser runs in high peak power pulse train mode. Comparing with pulsed YAG laser in free-running mode, its focused beam has higher laser power density which is helpful to result in less melt in laser drilling process. Several groups of laser drilling experiments in percussion mode have been finished with this laser. The experiments include making the holes by laser with different pulse duration, pulse frequency and pulse train energy and comparing the drilling results with axial flowing or side flowing assisted gas and without assisted gas. Materials of different thickness for drilling are Nickel-based alloys of different types, including single crystal, intermetallics and directional solidification alloy. Laser drilling experiments and metallographic examination of drilling samples show 150-550ns laser apparently improving the quality of the holes. The recast thickness normally is around 10µ or less, nearly no cracks have been found in recast inside holes. Conclusions and existing shortages based on the experimental results are given. The plan of research work in the next step is supposed.