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镍基高温合金纳秒脉冲激光制孔过程中,会沿孔壁形成一层再铸层,严重影响合金的使用寿命。考虑了熔体内热对流和热传导作用,以及反冲压力、表面张力、热毛细力等因素的影响,建立了镍基高温合金纳秒脉冲激光制孔的三维数学模型。开展了脉冲能量为24mJ时,各脉宽参数下纳秒脉冲激光制孔的数值模拟研究。模拟结果与实验吻合较好。结果表明再铸层是由热和力共同作用下形成的。制孔过程中,孔壁温度很高,最高温度达到3200K以上,孔壁温度分布不均匀;反冲压力是引起熔体流动的重要因素,反冲压力导致的熔体流动速度很大,脉宽200ns时,最大可达到60m/s;并且由于表面张力的影响,孔壁会出现许多不规则的凹陷和凸起。由于熔体在孔开口处的对流作用,导致再铸层厚度在开口处最大。脉宽对熔体流动和再铸层的形成具有重要影响,脉宽越小,熔体速度越大,流动越剧烈,制孔后形成的再铸层厚度越薄。
Nickel-based superalloy Nanosecond pulsed laser hole process will be formed along the hole wall layer of recast, seriously affecting the life of the alloy. Considering the effects of heat convection and heat conduction in the melt, as well as the influence of back pressure, surface tension and hot capillary force, a three-dimensional mathematical model of nanosillumination laser-induced nickel-based superalloy was established. When the pulse energy is 24mJ, the numerical simulation of nanosecond pulse laser perforation with each pulse width is carried out. The simulation results are in good agreement with the experiment. The results show that the recast layer is formed by the combined action of heat and force. In the process of making holes, the pore wall temperature is very high, the maximum temperature reaches more than 3200K, and the temperature distribution in the pore wall is uneven. The recoil pressure is an important factor that causes the melt flow. The melt flow velocity caused by the recoil pressure is very great. 200ns, up to 60m / s; and due to the surface tension of the hole wall will appear many irregularities and bumps. Due to the convection of the melt at the opening of the pores, the recast layer thickness is maximized at the opening. The pulse width has an important influence on the melt flow and the recast layer formation. The smaller the pulse width, the greater the melt velocity and the more severe the flow, the thinner the recast layer formed after the hole is formed.