研究生: |
黃祥生 HUANG HSIANG SHENG |
---|---|
論文名稱: |
Al-Mg-Zn合金電阻點銲微觀組織及拉伸強度變動之間關係探討 Effects of Spot Welding Condition on Ultimate Tensile Strength Variations of 7075-T6 Aluminum Alloy |
指導教授: |
呂傳盛
Lu, Chuan-Sheng 饒達欽 Rau, Dar-Chin |
學位類別: |
碩士 Master |
系所名稱: |
工業教育學系 Department of Industrial Education |
論文出版年: | 2001 |
畢業學年度: | 89 |
語文別: | 中文 |
論文頁數: | 101 |
中文關鍵詞: | 7075 、電阻點銲 、Al-Mg-Zn合金 |
論文種類: | 學術論文 |
相關次數: | 點閱:117 下載:2 |
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本研究係對鋁-鎂-鋅合金(7075-T6),利用單相交流式點銲機進行點銲試驗,所使用試片為厚度1.5mm之薄板。母材以搭接方式進行銲接,並施予不同製程參數(銲接電流、電極加壓力、通電時間)後,對試片進行金相顯微組織觀察、微硬度測試、拉伸試驗及SEM破斷面分析,並利用拉伸試驗所得之拉剪力強度進行韋伯分佈之可靠度分析,期望藉此研究能提供7075-T6鋁合金電阻點銲之應用參考。
經一系列試驗後所得之研究結果如下:
恰當之基礎製程參數:銲接電流14200A、電極加壓力2.2kg/cm2、通電時間19cycle。
點銲試片之微硬度分佈以nugget為中心大致呈左右對稱,銲塊區硬度最低,硬度值約Hv70,熱影響區約Hv110,母材部份約Hv165。拉伸試驗過程,破壞由銲塊中央及熱影響區開始發生均有可能。
在不同電流條件下,點銲試片拉剪力強度之可靠度韋伯模數m值介於2.07與4.86間。在不同電極加壓力下,點銲試片之拉剪力強度可靠度韋伯模數m值介於1.09與8.91間。在不同通電時間下,點銲試片之拉剪力強度可靠度韋伯模數m值介於4.29與7.80間。
在各試驗條件下,可靠度韋伯模數均大於1,屬於磨耗型破壞。
The characteristics were explored during resistance spot welding a commercial aluminum alloy 7075 in this study. The 7075 aluminum alloy sheets of 1.5mm gauges and in T6 condition were used in all experiments. Single spot weld was made on the specimens using a single-phase AC welding machine. The welding parameters were changed systematically, including welding current, electrode force and holding time. Metallographic studies were made by optical and scanning electron microscopy and microhardness was measured across the sectioned weldment using a hardness tester. The fluctuation behaviors of tensile-shear strength after welding have been analyzed by applying the Weibull distrbution function.
According to the experimental results, the proper welding parameters were 2.2kg/cm2electrode force,14.2kA welding current and 19 cycles of holding time. The hardness in the nugget is lowest,about Hv70,and the base 7075 alloy is highest. During tensile-shear testing, both nugget and heat affected zones (HAZ) are the regions for the fracture occurring. On the other hand, the reliability properties, such as tensile-shear strength distributions, reliability probabilities and minimum life, were calculated and predicted. All the tested results of Weibull modulus, m, are higher than one and the failure mode is‵wear-out′type.
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