铍的Nd:YAG激光焊接阈值功率影响因素

Influential factors of threshold power density for Nd:YAG laser beam welding of beryllium

关键词:  Nd∶YAG激光  阈值功率密度  铍

Key words:  Nd:YAG laser  threshold power density  beryllium

摘要:

利用Nd:YAG激光焊接了铍环,研究了不同激光入射角度和铍环直径变化对阈值功率变化的影响,得到了铍在激光焊接过程中阈值功率密度变化规律。结果表明,铍环直径大小对阈值功率密度有显著影响,随着铍环直径的增加,铍环的曲率减小,由背反射引起的调Q脉冲增强,导致出现深熔焊的阈值功率密度降低。对同一直径的铍环,激光入射角度从0°调整到3°后,由于消除了背反射激光在谐振腔内形成调Q脉冲,激光焊接时出现深熔焊的临界功率密度增加。深熔焊形成的焊缝深宽比值较大,为1.0~1.5,而热传导焊形成的焊缝深宽比值较小,只有0.2左右。

Abstract:

Laser threshold power density of hot isometric pressure(HIP) beryllium in laser beam welding was investigated.The results show that the threshold power density was sensitive to the diameter of beryllium cylinder.It is seemed that more large diameter of beryllium cylinder, more power of back-reflection light coupling into the resonator.So more strong Q-switched pulse was formed in the cavity.Then threshold power density of HIP beryllium will decrease. For the same diameter of bery llium cylinder, when the angel of incident laser beam was adjusted from 0° to 3°, the back-reflection laser can be overcome.Threshold power density of HIP beryllium will increase.In experiment, the ratio of depth to width usually is 1.0-1.5 for deep penetration welding.However, the ratio of depth to width usually is 0.2 for heat conduction welding.