(1. 燕山大學 機械工程學院，秦皇島 066004；
2. 河北省輕質(zhì)結(jié)構(gòu)裝備設(shè)計與制備工藝技術(shù)創(chuàng)新中心，秦皇島 066004；
3. 先進鍛壓成形技術(shù)與科學教育部重點實驗室(燕山大學)，秦皇島 066004)
摘 要: 通過理論、實驗和模擬相結(jié)合的方法，探究超聲振動在AZ31B鎂合金塑性成形中的“體積效應(yīng)”影響規(guī)律及作用機理。首先基于非局部理論建立了超聲振動AZ31B鎂合金的應(yīng)力疊加模型并通過模擬進行了驗證，然后基于熱激活理論和位錯演化理論，建立AZ31B鎂合金在超聲振動條件下的聲塑性模型，并結(jié)合實驗驗證了模型的準確性。結(jié)果表明：應(yīng)力疊加效應(yīng)導(dǎo)致的應(yīng)力下降值與超聲振動振幅參數(shù)正相關(guān)。引入超聲振動產(chǎn)生的應(yīng)力下降值可以通過應(yīng)力疊加效應(yīng)模型和聲塑性效應(yīng)模型刻畫。應(yīng)力疊加效應(yīng)導(dǎo)致材料的平均流動應(yīng)力發(fā)生振蕩而下降；聲軟化效應(yīng)指位錯吸收超聲能量克服釘扎效應(yīng)，從而利于材料塑性變形；聲殘余硬化效應(yīng)主要體現(xiàn)在高超聲能量導(dǎo)致材料位錯密度大量增殖，位錯在晶界處塞積、堆垛形成位錯墻，阻礙塑性流動，導(dǎo)致材料出現(xiàn)殘余硬化。
關(guān)鍵字: 超聲振動；應(yīng)力疊加效應(yīng)；聲塑性效應(yīng)；本構(gòu)模型
（1. College of Mechanical Engineering, Yanshan University, Qinhuangdao 066004, China;
2. Hebei Innovation Center for Equipment Lightweight Design and Manufacturing, Qinhuangdao 066004, China;
3. Key Laboratory of Advanced Forging Technology and Science of Education Ministry (Yanshan University), Qinhuangdao 066004, China）
Abstract:The studies of theory, experiment and simulation were carried out for exploring the “Volume Effect” rule and mechanism of ultrasonic vibration(UV) in plastic forming of magnesium alloy AZ31B. Firstly, the stress superposition model of UV for magnesium alloy AZ31B was established based on non-local theory. And the model was verified by simulation. Then, the UV acoustic plastic model of magnesium alloy AZ31B was established based on thermal activation theory and dislocation evolution theory. The accuracy of the model was verified by the experimental data. The results show that the stress drop is linearly and positively correlated with the UV amplitude. The stress superposition effect model and the harmonic plastic effect model can describe the stress dropping in the ultrasonic assisted forming. The superposition effect causes the average flow stress of the material to oscillate and decrease. Acoustic softening effect refers to the dislocation absorbs ultrasonic energy to overcome the nailing effect, which is beneficial to the plastic deformation of the material. Acoustic residual hardening effect mainly reflects in the high ultrasonic energy leading to a large number of dislocation density proliferation. The dislocation plugs up at the grain boundary to form a dislocation wall, causing the material flow to be blocked. Eventually, the material shows residual hardening.
Key words: ultrasonic vibration; effect of stress superposition; effect of acoustic plasticity; constitutive model
