异种铝合金搭接焊接头的疲劳特性及其寿命预测

Fatigue Behavior and Fatigue Life Prediction for Lap-welded Joint of Dissimilar Aluminum Alloys

采用冷金属过渡(CMT)焊技术对2.5 mm厚的6082合金板和A35合金板进行了搭接焊。采用电液伺服疲劳试验机以1 Hz恒频率、-1的应力比(R)和分别为0.2%、0.265%、0.4%、0.465%、0.535%的应变幅检测了搭接焊接头的疲劳特性。通过计算得到了搭接焊接头的低周疲劳特性参数σf′,b,εf′,c,K′,n′。通过参数拟合得到了搭接焊接头的应变-疲劳寿命关系曲线,并用于预测某车型的前副车架的疲劳寿命。台架试验和道路试验表明,样件的疲劳寿命与预测的一致。

2.5 mm-thick 6082 aluminum alloy sheet was lap welded on 2.5 mm-thick A356 aluminum alloy sheet by a cold metal transition(CMT)welding technology.The lap-welded joint was tested for fatigue behavior by using a electron-hydraulic servo fatigue testing machine under the conditions that the constant frequency was 1 Hz,the stress ratio R was-1,and the strain amplitudes were 0.2%,0.265%,0.4%,0.465%and 0.535%respectively.The low-cycle fatigue characteristic parameters of the lap-welded joint,such asσf′,b,εf′,c,K′and n′,were obtained by calculation.The dependence of fatigue life on strain for the lap-welded joint was obtained by parameter fitting,which was used to predict the fatigue life of the front sub-frame of a car.From the bench test and road test it was seen that the sample piece exhibited fatigue life according with the predicted result.