激光打孔孔壁重铸层的电解去除工艺研究
Electrochemical Machining Removal of Recast Layer of Laser Drilled Micro？？Holes

针对激光加工微小孔存在重铸层和微裂纹的问题,利用电解后处理进行去除。研制了激光？驳缃飧春霞庸な笛橄低？,并在GH4169镍基高温合金上进行了电解去除激光打孔孔壁重铸层的工艺研究,主要分析了电解电流、NaNO3溶液浓度和脉冲电解参数对电解速率和重铸层去除效果的影响。实验结果表明:当电流密度大于13.8 A/cm2时,电解速率与电流成正比例关系;恒流电解时,NaNO3溶液浓度对电解速率无影响,故可根据电流和电压确定其浓度;脉冲电解加工中低频宽脉冲、高频窄脉冲有利于电解速率的提高,且频率为1 kHz,占空比为40％～60％的电解速率最大,这是由于脉冲电解加工中产生氢气压力波,对加工间隙的电解液起到了良好的搅拌作用,提高了电流效率,电解速率随之增大。通过合适的电解加工参数,实现了激光制孔孔壁重铸层的完全去除。
For the appearance of recast layer and micro？？crack in laser drilled micro？？holes, electrochemical machining (ECM) is considered to reprocess the holes to eliminate these defects. The experimental system of hybrid processing of laser beam machining with ECM is developed. Nickel based superalloy GH4169 is used in the ECM experiment to explore the influences of electrolytic current, concentration of sodium nitrate solution and parameters of pulse electrochemical machining (PECM) on the electrolytic rate and the removal effect of recast layer. When the current density is larger than 13.8 A/cm2, the electrolytic rate is proportional to the current. The concentration of sodium nitrate solution has no effect on the electrolytic rate in constant current ECM. So the concentration can be determined by the current and the voltage. PECM with low frequency and wide pulse or with high frequency and narrow pulse is beneficial to the improvement of electrolytic rate. In particular, the electrolytic rate can get the maximum value at the frequency of 1 kHz and the duty ratio of 40％？？60％. PECM is accompanied by hydrogen pressure wave, which plays a good role in stirring the electrolyte in the machining gap. As a result, it can improve the current efficiency and increase the electrolytic rate. The recast layer of laser drilled micro？？holes can be removed completely by choosing appropriate ECM parameters