(北京工業(yè)大學 機械工程與應(yīng)用電子技術(shù)學院，北京 100124)
摘 要: 傳統(tǒng)鎂合金攪拌摩擦焊接過程中材料流動性能較低，從而焊縫容易出現(xiàn)缺陷。本文利用COMSOL仿真軟件，建立一種鎂合金載流靜軸肩攪拌摩擦焊(SSFSW)雙熱源數(shù)值模型，研究輸入電流對材料流動性能的影響。通過改變輸入電流參數(shù)進行數(shù)值模擬得到焊接過程溫度場，應(yīng)力場和速度場的演變規(guī)律。發(fā)現(xiàn)隨著電流的提高，溫度場分布沿焊縫厚度方向趨于均勻化，焊縫的溫度梯度降低，應(yīng)力場峰值從532 MPa降低至461 MPa，呈明顯降低趨勢，證明此時焊縫中材料流動性得到顯著提高。在電流達到150 A時，焊接溫度峰值接近于材料熔點650 ℃，在此溫度下易于得到無缺陷的焊縫和性能優(yōu)異的焊接接頭。數(shù)值模擬有效地預(yù)測實際焊接實驗中可能會出現(xiàn)的結(jié)果，減少為了得到合理焊接參數(shù)所需大量實驗的成本，并且仿真結(jié)果對工藝參數(shù)的選擇有重要的指導意義。
關(guān)鍵字: AZ31鎂合金；載流靜軸；肩攪拌摩擦焊；數(shù)值模型；溫度場；應(yīng)力場
（College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology, Beijing 100124, China）
Abstract:In the traditional magnesium alloy friction stir welding process, the material flow performance is low, so the weld is prone to defects. In this paper, COMSOL simulation software was used to establish a dual heat source numerical model for magnesium alloy current-carrying static shaft shoulder friction stir welding (SSFSW), and the influence of input current on material flow performance was studied. The evolution law of temperature field, stress field and velocity field in welding process was obtained by numerical simulation by changing the input current parameters. The results show that with the increase of the current, the temperature field distribution tends to be homogenized along the direction of the weld thickness, the temperature gradient of the weld decreases, and the peak stress field decrease from 532 MPa to 461 MPa, showing an obvious decreasing trend, which proves that the material liquidity in the weld is significantly improved at this time. When the current reaches 150 A, the peak welding temperature is close to the melting point of the material at 650 ℃. At this temperature, it is easy to get the weld without defect and the welded joint with excellent performance. The numerical simulation can effectively predict the possible results in actual welding experiments, reduces the cost of a large number of experiments in order to obtain reasonable welding parameters, and the simulation results will have important guiding significance for the selection of process parameters.
Key words: AZ31B magnesium alloy; electric assisted stationary shoulder friction stir welding; numerical mode; temperature field; stress field
