- 學位論文
Nd:YAG雷射鑽孔Ti-6Al-4V重鑄層特性之探討
An Investigation on the Characteristics of Recast Layer in Drilling Ti-6Al-4V by Using Nd:YAG Laser
摘要
本研究的目的是針對雷射鑽孔時探討入口端上表面重鑄層厚度及微裂縫長度之特性。利用Nd:YAG雷射加工機對厚度1. 0 mm的Ti-6Al-4V薄板進行循圓鑽孔，鑽孔的孔徑為2. 0 mm。選用的雷射加工參數包括尖峰功率、氣體壓力、脈衝頻率、脈衝寬度和循圓速率等五項，根據先期實驗得知對重鑄層厚度具有較重要影響的加工參數為尖峰功率及輔助氣體壓力，因此選定此兩項加工參數為變數，配置9組加工參數組合並進行鑽孔實驗，當完成循圓鑽孔後，量測重鑄層最大厚度及微裂縫最大長度，並求得各雷射鑽孔加工參數對上述量測結果的影響程度。結果顯示雷射尖峰功率及輔助氣體壓力確實是影響重鑄層厚度大小的重要因子。最後探討重鑄層和微裂縫之關聯性。經能量散佈分析儀(EDS)分析孔周圍不同層面之成分，切割面含有少量的碳，並無氧化情況發生。再以掃描式電子顯微鏡(SEM)量測孔入口端之上表面重鑄層最大厚度及微裂縫最大長度。結果顯示重鑄層最大厚度及微裂縫最大長度，會隨著雷射尖峰功率或輔助氣體壓力愈大呈現遞減之趨勢。而重鑄層最大厚度與微裂縫最大長度之間並無特別的關係存在。而微裂縫僅出現在輔助氣體壓力為1 kg/cm2時。本研究成果可提供給雷射鑽孔Ti-6Al-4V時之相關研究及產業界應用參考。
並列摘要
The purpose of this study is to investigate the characteristics of recast layer thickness and microcrack length for the entrance surface in laser drilling. An Nd:YAG laser machine is used to make 1.0mm thickness sheet of Ti-6Al-4V. The selected laser parameters include. The peak power, gas pressure, pulse frequency, pulse width and trepan speed. According to the preliminary experiments, the most important controlling parameters to the recast layer thickness are peak power and gas pressure. 9 sets of experiments are arranged with those two parameters for conducting experiments and the maximum thickness of recast layer and the maximum length of microcrack are measured after experiments finished. The results showed that the influence of the peak power and auxiliary gas pressure on the thickness of recast layer is proved. Finally, a correlation between the recast layer and microcrack is explored. An Energy Dispersive Spectrometer (EDS) is used to analyze the composition of different levels around the hole. It shows only a small amount of carbon exists on the cutted surface; however, no oxidation obtained, The maximum thickness of recast layer and the maximum length of microcrack are measured by scanning electron microscopy (SEM) on the surface of hole entrance side. The results showed that both the maximum thickness of recast layer and the maximum length of microcrack have a decreasing trend as the laser peak power or auxiliary gas pressure increasing. There is no specific relationship exists between the maximum thickness of recast layer and the maximum length of the microcracks. Microcracks appear only auxiliary gas press is 1 kg/cm2. The research results can provide reference as laser drilling Ti-6Al-4V of the research and industry application.