本論文旨在評估應用放電加工鑽孔法(EDM Hole-Drilling Method)量測殘留應力之可行性，測試的材料包含AISI D2冷作工具鋼、AISI H13熱作工具鋼及AISI 1045中碳鋼。放電加工鑽孔的品質以加工速率、表面形貌及材料顯微結構來加以評估，如材料移除率(MRR)、電極消耗率(EWR)、表面粗糙度(SR)、擴孔量(HE)、白層厚度(WLT)、表面裂縫及鑽孔引進應力（σHI.S.）等。本研究以無應力試件（Non-stressed samples）之放電鑽孔應力量測結果來評估放電加工參數、白層厚度、材料硬度、材料熱傳導係數等，對鑽孔引進應力之影響，並以預應力試件(Pre-stressed samples)之應力量測來評估殘留拉伸及壓縮應力場的大小對鑽孔引進應力的影響程度。在放電加工表面白層的微觀結構及硬度分佈，則以掃瞄式電子顯微鏡(SEM)、穿透式電子顯微鏡(TEM)及奈米壓痕技術 (Nano-indentation techniques)來進行分析。

　　本研究為確認放電加工鑽孔法之量測穩定性與準確性，將放電鑽孔應力量測結果與工業界常用的高速鑽孔法(High Speed Hole-Drilling Method)之量測結果作比對。由無應力試件之研究結果顯示，白層厚度與放電加工鑽孔引進應力呈現線性正比關係，又材料熱傳導係數越高，白層厚度越薄，故本研究以材料熱傳導係數(k)為觀點，提出一校正程序以正向補償放電加工鑽孔法所引進的額外鑽孔壓應力，此外，並配合材料碳當量（Carbon Equivalent, Ceq.）的概念來估計材料之熱傳導係數，有助於放電加工鑽孔法之校正應力(σcal.)的計算。由預應力試件的量測結果可知，無論是在拉伸或壓縮預荷應力場下，使用相同的放電加工條件其所引進的鑽孔壓應力值幾乎不受外加應力場（Pre-stress）的影響。因此，以放電加工鑽孔的方式搭配應變規鑽孔法(ASTM standard E837)的規範，提供了另一種量測高硬度、耐磨耗材料之殘留應力的可行方法。

　　This study investigates the application of EDM Hole-Drilling Method to the measurement of residual stress in AISI D2 cold work tool steel, AISI H13 hot work tool steel, and AISI 1045 medium carbon steel. The quality of an EDM drilling hole is evaluated in terms of its machining ability and surface integrity, such as Material Removal Rate (MRR), Electrode Wear Rate (EWR), Surface Roughness (SR), Hole-Enlargement (HE), the presence of white layer thickness (WLT), surface cracks, and the hole-drilling induced residual stress (σHI.S.). The influences of EDM parameters, white layer thickness, hardness, thermal conductivity of materials in hole-drilling induced stress were analyzed by performing stress measurements on a series of non-stressed samples. The influence of the magnitude of tensile and compressive pre-stress state in hole-drilling induced stress was evaluated by pre-stressed samples. SEM, TEM and nano-indentation techniques were used to examine the microstructure and hardness of the white layer formed on the EDMed surface.

　　In order to confirm the measurement stability and accuracy of EDM Hole-Drilling Method, all the experimental results were compared with those obtained by High-Speed Hole-Drilling Method, which is most widely used in industry. From the experimental results of non-stressed samples, there is a linear equation between the white layer thickness and hole-drilling induced stress. Moreover, higher is the thermal conductivity; thinner is the white layer thickness. Therefore, a calibration procedure based on the thermal conductivity (k) of the material is proposed to compensate positively for the additional compressive stress induced by the EDM hole-drilling process. Besides, the relationship between carbon equivalent (Ceq.) and thermal conductivity was established to calculate conveniently the calibration stress (σcal.) of EDM Hole-Drilling Method. The measurement results of pre-stressed samples reveal that the hole-drilling induced stress by a certain EDM condition is independent of the magnitude of pre-stress filed; no matter it is tension or compression. Therefore, the EDM drilling process combining with the Hole-Drilling Strain-Gage Method (ASTM standard E837) provides an feasible means of determining the residual stress in materials with high hardness and good wear resistance.

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