To fabricate small holes in a nickel-based single crystal superalloy without formation of recast layer and stray corrosion, electrochemical discharge drilling utilising a compound flow field of different fluids (DF-ECDD), is investigated in this study. DF-ECDD is a compound machining method that electrical discharge machining (EDM) and electrochemical machining (ECM) can occur simultaneously in the process. In this method, the internal flushing of a low-concentration salt solution and external flushing of a deionized water occur simultaneously. By means of the internal flushing, EDM and ECM occur synchronously in the process. Owing to the external flushing, the conductivity of the solution on the surface of the workpiece is significantly reduced, thus reducing the stray electric field distribution. In this study, the influence of the conductivity of the external flushing liquid in the DF-ECDD process was analysed. The simulation results showed that when deionized water with a conductivity of 2 μS/cm was used as the external flushing liquid, the stray current on the workpiece surface was almost completely eliminated. Furthermore, the expression is theoretically derived for the relationship between the radii of the stray corrosion areas and the conductivity of solution domain. The experiments verified that the radii of the stray corrosion areas decrease with the decreasing of external flushing liquid conductivity. Finally, the stray corrosion could also be almost eliminated with the DF-ECDD process, and the machined holes were free of recast layer.

为了在镍基单晶高温合金中制造小孔而不形成重铸层和杂散腐蚀，本研究研究了利用不同流体复合流场 (DF-ECDD) 的电化学放电钻孔。DF-ECDD是一种可以同时进行放电加工（EDM）和电化学加工（ECM）的复合加工方法。在该方法中，低浓度盐溶液的内部冲洗和去离子水的外部冲洗同时发生。通过内部冲洗，EDM 和 ECM 在过程中同步发生。由于外部冲洗，工件表面溶液的电导率显着降低，从而减少了杂散电场分布。在这项研究中，分析了DF-ECDD过程中外部冲洗液电导率的影响。仿真结果表明，当使用电导率为2 μS/cm的去离子水作为外部冲洗液时，工件表面的杂散电流几乎完全消除。此外，该表达式是从理论上推导出杂散腐蚀区域半径与溶液域电导率之间的关系。实验验证了杂散腐蚀区域的半径随着外部冲洗液电导率的降低而减小。最后，DF-ECDD工艺也几乎可以消除杂散腐蚀，加工孔没有重铸层。仿真结果表明，当使用电导率为2 μS/cm的去离子水作为外部冲洗液时，工件表面的杂散电流几乎完全消除。此外，该表达式是从理论上推导出杂散腐蚀区域半径与溶液域电导率之间的关系。实验验证了杂散腐蚀区域的半径随着外部冲洗液电导率的降低而减小。最后，DF-ECDD工艺也几乎可以消除杂散腐蚀，加工孔没有重铸层。仿真结果表明，当使用电导率为2 μS/cm的去离子水作为外部冲洗液时，工件表面的杂散电流几乎完全消除。此外，该表达式是从理论上推导出杂散腐蚀区域半径与溶液域电导率之间的关系。实验验证了杂散腐蚀区域的半径随着外部冲洗液电导率的降低而减小。最后，DF-ECDD工艺也几乎可以消除杂散腐蚀，加工孔没有重铸层。该表达式是从理论上推导出杂散腐蚀区域半径与溶液域电导率之间的关系。实验验证了杂散腐蚀区域的半径随着外部冲洗液电导率的降低而减小。最后，DF-ECDD工艺也几乎可以消除杂散腐蚀，加工孔没有重铸层。该表达式是从理论上推导出杂散腐蚀区域半径与溶液域电导率之间的关系。实验验证了杂散腐蚀区域的半径随着外部冲洗液电导率的降低而减小。最后，DF-ECDD工艺也几乎可以消除杂散腐蚀，加工孔没有重铸层。