摩擦攪拌銲接進給速度對5086鋁合金機械性質與微結構影響之研究

Effect of Welding Speed of Friction Stir Welding on Mechanical Properties and Microstructure for 5086 Aluminum Alloy

劉兆欽(Chao-Chin Liu)

指導教授 ： 于劍平

崑山科技大學/工程學院/機械工程研究所/碩士(2010年)

摘要

本研究係針對5086鋁合金材料利用摩擦攪拌銲接法經過不同進給速度銲接加工後，探討其對機械性質及微結構之影響。5086鋁合金係鋁鎂系中強度合金，具有良好的耐蝕性及熔接性，常被用在建造船舶載具、海運業及鹽水成分較高的地方使用。目前使用鋁合金建造船舶載具時，考量生產製造成本、構件接合部位與工作環境限制等因素，因此多以氣體鎢極電弧銲接法或惰性氣體金屬線電弧銲接法來進行銲接加工作業。但限於此兩類高溫銲接加工，受輸入熱量影響，而影響母材之性質及產生銲道缺陷，為獲得較高品質成品，故以摩擦攪拌銲接法探討經過不同進給速度銲接後，對銲件銲後機械性質之影響，進而決定材料適當之進給速度，以確保銲件品質。
本文先將試件進行不同進給速度銲接加工處理，利用X-ray檢驗銲道品質，並藉拉伸試驗、金相顯微組織觀察、硬度量測及拉伸試片斷口分析，加以探討5086鋁合金經不同進給速度銲接加工後，試件之銲核區、熱機影響區、熱影響區及母材區等機械性質與微結構之變化與研究。
由實驗結果得知，試片銲道邊緣兩側花瓣狀材料溢出量最少者發生銲道缺陷情況較少，銲道截面硬度值分佈呈U形，硬度最小值發生在熱影響區與熱機影響區之間，銲核區域硬度均較熱影響區為高，但均低於母材硬度值。以掃描式電子顯微鏡觀察各實驗組拉伸斷口，均具韌窩結構，屬延性破壞。

關鍵字

摩擦攪拌銲接 ； 5086鋁合金 ； 進給速度 ； 掃描式電子顯微鏡

並列摘要

The study investigates mechanical properties and microstructure effect for 5086 aluminum alloy with different welding speed of friction stir welding. The 5086 aluminum alloy has good corrosion resistance and welding quality, which often used in the construction of the ship, shipping industry and places that contain some rich-salt regions. Now when we use aluminum alloy to build equipment of ship, there are many factors to consider, for example, the cost of production, the portion of working parts and the limitation of working environment. Therefore, we usually use gas tungsten arc welding（GTAW）and inert gas metal arc welding（GMAW）to proceed the operation of welding. But the input heat affected the properties of base metal and induced the welding defects for the both of welding methods. In order to acquire the welding workpiece with higher quality, we investigate the influence of mechanical properties with different welding speed for FSW, and then select the proper welding speed for Al maternal and ensure the quality of welding parts.
Firstly, the welding process is employed with different welding speeds for the workpiece, and then X-ray is used to examine the welding quality. Based on the tensile experiment, metallographic observation, hardness measurement and fractography analysis of tensile test, after welding the FSW with different welding speeds for 5086 AL alloy is investigated. This study is then conducted on the variation of the mechanical properties and microstructure of the workpiece of welded nugget, the thermo mechanically affected zone（TMAZ）, the heat affected zone（HAZ）and the base material.
Based on the results of experiment, the less petal-pattern materials are spilled in two side edge of welding path, the less defects are occurred. And the distribution of hardness on the cross-section of welding path is U-shape. The minimum hardness occurs between HAZ and TMAZ. And the hardness in the nugget region is higher than those in the HAZ. But the hardness in the nugget region is lower than the base metal. The SEM is employed to observe the fractography of tensile for each experiment, the fracture with dimple structure is ductile failure.

並列關鍵字

Friction stir welding ； 5086 Aluminum alloys ； Welding speed ； Scanning Electron Microscopy（SEM）

參考文獻

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