Numerical Simulation Study Of Nanosecond Pulse Laser Drilling Process On Nickel-based High-temperature Alloy

Nickel-based high-temperature alloy has many advantages, such as, high hardness,high strength, good temperature resistance and good corrosion resistance, That is widelyused in aeroengine turbine blade manufacturing. In order to improve the turbine blade’scapacity of cooling, we often manufacture a series of holes on the blade. But nickel-basedhigh-temperature alloy is typical difficult-to-machine materials with big cutting force,high cutting temperature and serious hardening phenomenon. So, we adopt nanosecondpulse laser drilling technology processing nickel-based high-temperature alloy. Thistechnology has many advantages, such as, fast drilling velocity, low cost, high efficiency,small deformation and wide applicable. Nanosecond pulse laser drilling is very fast, andthe physical mechanism is complicated, we can only get the hole morphology of drillingprocess through the experiment. In this paper, by using the method of numericalsimulation, the hole morphology evolution, temperature field evolution, flow fieldevolution and drilling mechanism of nanosecond pulse laser drilling were studied. Themajor works are listed below:(1) A three dimensional mathematical model of nanosecond pulse laser drilling onNickel-based high-temperature alloy is established. The model can be used to simulate thethe three-dimensional temperature field, flow field evolution, the formation process ofhole and then recast layer on nanosecond pulse laser drilling. The simulated results agreewell with experiment results.(2) The evolution of the hole morphology, temperature field, flow field and theformation of recast layer process are simulated. The results showed: the temperature ofkeyhole wall is very high, and the temperature distribution of keyhole wall is not uniform.There is a thin layer of high temperature melt In the hole wall. Besides, recoil pressure is an important factor to cause the melt flow, and the velocity of melt flow caused by recoilpressure is very large. Affected by the surface tension, surface of the melt will appearconvex and concave, which lead hole wall not smooth at the end of the drilling. Thenrecast layer formation is formed under the action of jointly by heat and power. Due to theconvection of melt in the keyhole’s opening, recast layer in this place is the thickest.Laser width has a great effect on the formation of recast layer, the greater pulse widthmakes the bigger recast layer thickness, and the greater melt velocity.