摩擦攪拌點銲(FSSW)為摩擦攪拌銲接(FSW)的擴充應用，其為一固態接合技術，由於過程中溫度未達熔點，故無氣孔、凝固裂紋等傳統熔融銲接所產生之缺陷，所以特別適合鎂、鋁合金等輕金屬點銲的應用。
實驗結果發現暫態拘束空間(Constraint space)之建立，為形成攪拌區及銲件接合行為的必要條件。摩擦攪拌點銲期間，除工具的攪拌作用(Traction force)直接造成材料的塑性流動外，由於攪拌工具幾何形狀在拘束空間內造成的壓力梯度(孔隙效應)更是引發材料軸向或徑向流動及形成攪拌區的關鍵因素，而攪拌區的形成及成長將影響板材的接合行為及上板材厚度減少的趨勢，進而影響銲件之機械性質。因此適當的攪拌工具設計將可大大提升銲件的接合效能。而適當的製程參數也是形成良好銲件的必要條件。三角柱凸銷及螺紋圓柱凸銷以不同的塑性流動機制形成攪拌區，螺紋圓柱凸銷驅動材料軸向流動的效應高於光滑三角柱凸銷；但三角柱的凸銷其驅動材料徑向(Radial direction)流動的效應，則高於螺紋圓柱凸銷。因此兩者的銲件具有十分不同的銲道形貌。由於Hook幾何形狀的差異，其拉剪破壞模式及強度也明顯不同。螺紋圓柱凸銷製程之銲件其拉剪強度略高於三角柱製程之銲件。
本文建立不同幾何形狀的工具之摩擦攪拌點銲(FSSW)材料流動的模式，並藉由追蹤物(tracer)技術及實驗觀察來闡述攪拌工具的肩部及凸銷之幾何形狀對材料塑性流動及板材接合的效應，並提出攪拌區(SZ)形成機制，以及銲接參數對銲件破壞模式及接合強度之效應的論述，期能對FSSW的工具設計提供參考。

Friction stir spot welding (FSSW) is a derivative process of the friction stir welding (FSW), which is a solid-state joining technique, due to the process temperature below the melting point, so it therefore does not exit porosity, solidification cracking and other defects generated by traditional fusion welding. It is especially suitable for magnesium, aluminum and other light metal alloys.
Results showed that, the construction of the transient constrained space is a prerequisite to the formation of a stirring area and the bonding of the welding work pieces. Friction stir spot welding (FSSW) is driven mainly by the materials flow induced by the stirring tool in a constrained space that gradually diminishes the contact interface between the upper and lower plates leaving them bonded to each other. The stirring tool has a decisive influence on the flowing behavior of the plastic and the bonding strength of the welding work pieces.
During the FSSW period, except for the traction force of the tool that can directly cause the flow of plastic materials, the pressure gradient generated in the constrained space by the tool geometry that causes the axial or radial flow of the materials and the formation of a stir zone are even more key factors. The formation and growth of the stir zone will influence the bonding behavior of the plates and the effective thickness reduction trend of the upper plate. This will further influence the mechanical strength of the welding work pieces. Therefore, the appropriate design of the stirring tool can greatly improve the bonding performance of the welding work pieces. In addition, appropriate process parameters are also a prerequisite to the formation of well-welded work pieces.
The triangular tool pin and the threaded cylindrical tool pin will form stir zone caused by the different plastic flow mechanisms. The threaded cylindrical tool pin has a higher performance than the smooth triangular tool pin when driving the axial flow of materials. However, the triangular tool pin has a higher performance than the threaded cylindrical tool pin when driving the radial flow. Therefore, the nuggets of welding working pieces of the two types are totally different in their geometric features. Because of the geometrical differences of the hook, its tensile shear failure modes and strength also have significant differences. The welding work pieces made by the process using the threaded cylindrical tool pin has a slightly higher tensile and shear strengths than those made by the process using the triangular tool pin.
This study established the FSSW materials flow modes using different geometrical tools as well as observations from the experiments. It has also used tracer techniques to elaborate on the influences on the flow of materials and the bonding effect of the plates induced by the shoulder of the stirring tool and the geometrical shapes of the tool pin. The formation mechanism of the stirring zone was presented and the effects of the welding parameters on the welding work piece failure modes and their bonding strength were also discussed. This was done in the hope of providing more useful references for the FSSW tool design.

摘 要 I
ABSTRACT III
誌 謝 V
目 錄 VI
表目錄 X
圖目錄 XI
第一章 前言 1
1.1 摩擦攪拌銲接(FSW) 1
1.2 摩擦攪拌點銲(FSSW) 2
1.3 研究動機 3
第二章 文獻回顧 6
2.1製程參數 6
2.1.1 攪拌工具之幾何形狀 (Tool geometry) 6
2.1.2 銲接參數 (Welding parameters) 10
2.2 摩擦攪拌點銲過程 14
2.2.1 材料流動(Material flow) 14
2.2.2 溫度分佈 17
2.3 微觀組織發展 (Microstructural evolution) 18
2.3.1 攪拌區 19
2.3.2 熱機影響區(TMAZ)與熱影響區(HAZ) 21
2.3.3接合界面 (Bond interface; Hook) 21
2.4研究目的 24
2.5研究架構 25
第三章 摩擦攪拌點銲材料流動模式的機理 30
3.1凸銷擠入階段的材料流動 30
3.2摩擦攪拌點銲製程保持階段的材料流動 31
3.2.1螺紋圓柱凸銷攪拌工具之摩擦攪拌點銲製程 32
3.2.2光滑圓柱凸銷攪拌工具之摩擦攪拌點銲製程 33
3.2.3光滑三角柱凸銷攪拌工具之摩擦攪拌點銲製程 34
3.2.4螺紋三角柱凸銷攪拌工具之摩擦攪拌點銲製程 35
3.3摩擦攪拌點銲製程的保持階段影響材料流動的重要因素 35
第四章 實驗方法 42
4.1 試片準備 42
4.2攪拌工具 42
4.3摩擦攪拌點銲設備 43
4.4實驗規劃 43
4.4.1材料流場分析 43
銲接參數對銲件接合的影響 44
4.5組織觀察 44
4.5.1銲道觀察 44
4.5.2晶粒尺寸觀察 44
4.5.3追蹤粉末的位置及觀察 45
4.6硬度 45
4.7 拉剪試驗 45
第五章 A6061-T6之摩擦攪拌點銲製程材料流場分析 51
5.1攪拌工具擠入過程上板材料的塑性流動 56
5.2攪拌工具的幾何形狀對摩擦攪拌點銲材料流動的效應 57
5.2.1 TC摩擦攪拌點銲製程材料塑性流動分析 57
5.2.2 SC摩擦攪拌點銲製程材料塑性流動分析 60
5.2.3 ST摩擦攪拌點銲製程材料塑性流動分析 62
5.2.4 TT摩擦攪拌點銲製程材料塑性流動分析 64
5.3綜合討論 65
第六章 製程參數對A6061-T6之摩擦攪拌點銲銲件之效應 84
6.1攪拌工具形貌對摩擦攪拌點銲銲件強度的效應 84
6.1.1攪拌工具對摩擦攪拌點銲銲件之硬度分佈的效應 84
6.1.2攪拌工具形貌對摩擦攪拌點銲銲件之拉剪破壞性質之效應 85
6.2製程參數對TC摩擦攪拌點銲之效應 90
6.2.1 工具轉速對摩擦攪拌點銲之效應 90
6.2.2 工具保持時間對摩擦攪拌點銲之效應 93
6.2.3 工具擠入深度對摩擦攪拌點銲之效應 96
6.3製程參數對ST摩擦攪拌點銲之效應 98
6.3.1 工具轉速對摩擦攪拌點銲之效應 98
6.3.2 工具保持時間對摩擦攪拌點銲之效應 99
6.3.3 工具擠入深度對摩擦攪拌點銲之效應 100
6.4綜合討論 101
第七章 結 論 129
References 132

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