本文選題：2024鋁合金 + 筒形件拉深��； 參考：《南京航空航天大學(xué)》2017年碩士論文

【摘要】：鋁合金由于質(zhì)量輕、節(jié)能等優(yōu)點(diǎn)在工業(yè)中得到廣泛運(yùn)用,但室溫下低塑性和高溫成形下零件表面質(zhì)量差等缺點(diǎn)制約了鋁合金的發(fā)展。而研究表明電流輔助成形(電致塑性)可在較低溫度下使材料塑性提高,故本文對電流輔助作用下的AL-(3.8-4.9)Cu-(1.2-1.8)Mg鋁合金板力學(xué)性能以及筒形件拉深成形進(jìn)行了一定程度的研究。首先通過分別在未通電室溫下、高頻(25-100hz)及低頻(0-0.5hz)電流輔助作用下單軸拉伸實(shí)驗(yàn),研究了板材的力學(xué)性能,并對高頻作用下曲線進(jìn)行擬合得到本構(gòu)方程;通過熱電耦合有限元模擬分析了材料在單拉過程中電場和溫度場的分布、筒形件拉深工藝中的電場和溫度場分布以得到優(yōu)化的電極接入方式;結(jié)合模擬仿真結(jié)果設(shè)計(jì)并進(jìn)行了未通電室溫下、“壓邊圈—凹模”通電下、“凸�！寄！蓖娤碌耐残渭顚�(shí)驗(yàn);通過光學(xué)組織觀察、SEM斷口分析研究了不同電參數(shù)作用下材料微觀組織演化過程。研究結(jié)果表明:高頻脈沖電流輔助條件下,材料隨著電流密度、電流頻率以及電流脈寬的增加,材料的延伸率、流變應(yīng)力減小;并通過耦合電參數(shù)的J-C修正模型擬合的本構(gòu)關(guān)系平均誤差在5%以內(nèi)。低頻脈沖電流輔助條件下,材料在50A/mm2的電流預(yù)處理后或者90A/mm2的電流預(yù)處理后時(shí)效24小時(shí),延伸率較室溫下有17.6%的提升;在無預(yù)變形條件下,材料延伸率、強(qiáng)度隨著電流密度增加而減小;在有預(yù)變形條件下,電流密度為110 A/mm2、150 A/mm2材料延伸率較無電流拉伸分別提高了29.4%、47.6%。“壓邊圈—凹�！蓖娎顚⒗罡叨忍岣吡私�134%,而凸模—凹模通電拉深卻難以拉深成形。150 A/mm2脈沖電流作用下,材料在153度就發(fā)生了動態(tài)再結(jié)晶,通電拉深所得筒形件的凸模圓角區(qū)域、凹模圓角區(qū)域的晶粒較室溫下有明顯減小,且發(fā)生了動態(tài)再結(jié)晶。
[Abstract]:Aluminum alloy is widely used in industry because of its advantages of light weight and energy saving. However, the development of aluminum alloy is restricted by the shortcomings of low plasticity at room temperature and poor surface quality of parts under high temperature forming. The results show that the plastic properties of AL-(3.8-4.9)Cu-(1.2-1.8)Mg aluminum alloy sheet under the condition of current assisted forming (EPS) can be improved at lower temperature, so the mechanical properties of the AL-(3.8-4.9)Cu-(1.2-1.8)Mg aluminum alloy sheet and the deep drawing of the cylindrical part are studied to a certain extent in this paper. At first, the mechanical properties of the plate were studied by the order axis tensile experiment under the condition of unelectrified room temperature, high frequency (25 ~ 100hz) and low frequency (0 ~ 0.5hz) electric current. The constitutive equation was obtained by fitting the curve under the high frequency action. The distribution of electric field and temperature field in single drawing process and the distribution of electric field and temperature field in cylindrical drawing process were analyzed by thermoelectric coupling finite element simulation. Based on the simulation results, the experiments of drawing the cylindrical parts under the current of "blank holder ring-die" and "convex die" at room temperature without electrification are carried out. The microstructure evolution process of materials under different electrical parameters was studied by SEM fracture analysis. The results show that with the increase of current density, current frequency and current pulse width, the elongation and flow stress of the material decrease with the increase of current density, current frequency and current pulse width. The average error of constitutive relation fitted by J-C modified model with coupled electrical parameters is less than 5%. Under the condition of low frequency pulse current assisted, the elongation of the material aged 24 hours after the current pretreatment of 50A/mm2 or the current pretreatment of 90A/mm2 was 17.6% higher than that at room temperature, and the elongation of the material without predeformation was 17.6% higher than that at room temperature. The tensile strength decreases with the increase of the current density, and the elongation of the material with current density of 110 A/mm2150 A/mm2 is increased by 29.4% and 47.6%, respectively, compared with that of the non-current tension under the condition of pre-deformation. The "blank holder ring-die" electric drawing raised the drawing height by nearly 134k.However, when the protrusion-die electrified drawing was difficult to draw deeply, the material was dynamically recrystallized at 153C under the action of the pulse current of .150. The grains in the corner region of the convex die and the corner region of the die are obviously smaller than those at room temperature, and dynamic recrystallization occurs.
【學(xué)位授予單位】：南京航空航天大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG389

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本文編號：1926677