(1. 福州大學 機械工程及自動化學院，福州 350116；
2. 中冶瑞木新能源科技有限公司，唐山 063299)
摘 要: 通過超聲振動輔助熱拉伸實驗，研究溫度和超聲振動對AZ31B鎂合金板材力學行為的影響。結(jié)果表明：熱振聯(lián)合作用下材料的屈服強度和抗拉強度下降，伸長率和塑性提高，動態(tài)再結(jié)晶延遲發(fā)生。隨著振幅的增加，屈服強度和抗拉強度降低的幅度增加，伸長率先增大后減小。與無振動時的伸長率對比，當振幅為9.1 μm時，伸長率增大的幅度最大，分別為32.3%(150 ℃)和23.2%(200 ℃)。基于熱激活機制和位錯密度演化理論構(gòu)建超聲振動下鎂合金熱拉伸的本構(gòu)關系模型，并結(jié)合實驗驗證模型的準確性。該本構(gòu)模型能有效地預測不同溫度和振幅下材料的應力-應變關系，預測曲線與實驗曲線吻合較好。該模型的建立為超聲振動下金屬熱塑性成形的有限元模擬提供了理論基礎。
關鍵字: 鎂合金；本構(gòu)建模；超聲輔助；拉伸實驗；力學行為
（1. School of Mechanical Engineering and Automation, Fuzhou University, Fuzhou 350116, China;
2. MCC Ramu New Energy Technology Co., Ltd., Tangshan 063299, China）
Abstract:The effects of temperature and ultrasonic vibration on the mechanical behavior of AZ31B magnesium alloy sheet were studied by ultrasonic vibration assisted hot tensile tests. The results show that with the applying of the ultrasonic vibration, the yield strength and tensile strength are decreased, the elongation and plasticity are improved, and the onset of the dynamic recrystallization is delayed. With the increase of the amplitude, the yield strength and tensile strength further decrease, while the elongation first increases and then decreases. Comparing with that without ultrasonic vibration, the elongation under the vibration of 9.1 μm increases by 32.3% (150 ℃) and 23.2% (200 ℃), respectively, to the maximum extent among the experimental results. Based on the thermal activation mechanism and dislocation density evolution theory, the constitutive model used to describe the hot tensile behavior of Mg alloy sheet under ultrasonic vibration is established. The performance of this model is evaluated by the experiment. The model can effectively predict the stress-strain responses of materials under different temperatures and amplitudes, and the predictive curves are in good agreement with the experimental curves. It provides a theoretical basis for the finite element simulation of metal sheet in hot plastic forming under ultrasonic vibration.
Key words: magnesium alloy; constitutive model; ultrasonic vibration; tensile test; mechanical behavior
