鋁合金厚板攪拌摩擦焊接製程分析

攪拌摩擦焊接是一種新型的固相連接技術，具有焊接接頭性能好、節能、環保和適應性廣等特點。該焊接方法在製造成本和焊接品質等方面具有許多優點，已經廣泛的應用於航太、高速列車、輪船、汽車等製造領域。鋁合金厚板的用途很廣，研究厚板焊接技術，以提高厚板作為結構件的整體強度，具有重要的實用價值。在厚板攪拌摩擦焊接的接合過程中，必須克服的問題主要是沿板厚方向溫度梯度較大、下層金屬溫度偏低且金屬塑性流動不充分，及下層接合處強度較弱等。本論文針對14mmA3003 厚板採用攪拌摩擦焊技術對接，開發出適合鋁合金厚板對接的攪拌頭及焊接製程。在本試驗中，將攪拌摩擦焊接用的攪拌頭之幾何形狀分別設計成螺紋開槽型和Whisk 螺紋開槽型（攪拌針頂部加工成攪拌器形狀）兩種。其次，藉由改變焊接速度和旋轉速度，分析製程參數對接頭抗拉強度的影響。當採用Whisk 螺紋開槽攪拌頭進行實驗分析時，旋轉速度設定為1200 rpm，焊接速度F＝120mm/min 至190mm/min 之間變化，分析結果顯示，接頭的抗拉強度均能達到母材的97％以上。當焊接速度F＝150mm/min，旋轉速度設定於1000 rpm 至1400 rpm 之間變化時，分析結果顯示接頭抗拉強度均在母材的96％以上。此外，當選用螺紋開槽攪拌頭進行實驗分析時，所得到的無缺陷焊縫之製程參數範圍比Whisk 螺紋開槽攪拌頭為窄。攪拌摩擦焊接頭是在摩擦和攪拌同時作用下形成的，螺紋開槽及攪拌針頂端加工成攪拌器形狀等兩種接頭形狀的設計，有助於加強攪拌作用，促進塑性變形潛熱的釋放，減小板厚方向上的溫度梯度，同時使下層塑性金屬流動較為充分、並能促使焊縫晶粒發生動態再結晶，進而有效地解決接頭下層性能較差的問題。

關鍵字

攪拌摩擦焊接；鋁合金；厚板

並列摘要

Friction Stir Welding(FSW) is a solid-state joining process. A number of potential advantages of FSW over conventional fusion-welding processes have been identified. such as good mechanical properties、Energy saving, low environmental impact and wide adaptability. Because of the low cost and high quality, the FWS has been widely used in aerospace, high-speed trains, ships, cars and other manufacturing fields. Thick aluminum-alloy plate is widely being used in the manufacture, to improve the strength of structure, the technology of thick plate welding should be researched. The main problem with thick plate FSW are temperature gradient along with thickness direction、lower temperature of the lower part and plastic flow not enough, so the lower part is the weak portion of the joints. In this paper, 14mm A3003 thick plate being jointed by Friction Stir Welding, the FSW tool and welding process have been developed. During the test process, the profile of FSW tool being designed with 「screw groove pattern」 and 「whisk screw groove pattern」 which has a whisk pattern at thetop end of the FSW tool. By means of changing the welding speed and rotation speed,the influence of the welding parameters on the joint’s tensile strength isstudied. While 「whisk screw groove pattern」 FSW tool being used with the Rotation speed 1200 rpm and the welding speed changes from 120 mm/min to 190mm/min,the joint’s tensile strength is above 97％ of the base-material. While the Rotation speed changes from 1000 rpm to 1400 rpm with the welding speed 150 mm/min,the joint’s tensile strength is above 96％ of the base-material. But while 「screw groove pattern」 tool being used, the proper parameters range which no-defect joints can obtained is narrower than 「whisk screw groove pattern」. So in order to obtain high quality joints, 「whisk screw groove pattern」 FSW tool should be used. The FSW joint is made by the synthesis effect friction and stir, to make thewhisk pattern at the top end of FSW tool can reinforce the stir for the plastic metal, promote given off the heat of plastic deformation and temperature gradient along with thickness direction decreased. At the same time, the whisk patter of the tool has an effect to reinforce flow behavior of the plastic metal、to improve dynamic recrystallization course occur in the crystal grain of weld nugget, so the problem thatthe lower part has a weak performance can be solved