本文關(guān)鍵詞： 筒形件 多道次單向及交叉旋壓 3A21鋁合金 晶體塑性 變形織構(gòu)　出處：《哈爾濱工業(yè)大學(xué)》2017年碩士論文　論文類(lèi)型：學(xué)位論文

【摘要】：筒形件旋壓是典型的局部加載成形工藝,具有省料、成形性能好、工裝簡(jiǎn)單等優(yōu)點(diǎn),是制造大型薄壁無(wú)縫筒形件的有效方法,已廣泛用于航天、航空、兵器、艦船和機(jī)械等工業(yè)領(lǐng)域。由于旋壓變形過(guò)程非常復(fù)雜,影響因素眾多,到目前為止,大量的旋壓技術(shù)研究工作仍定位于零件成形,旋壓缺陷和幾何精度控制等方面,零件力學(xué)性能控制方面考慮得較少。晶體學(xué)織構(gòu)能對(duì)金屬材料力學(xué)性能產(chǎn)生重大影響,織構(gòu)也就成為控制材料力學(xué)性能的重要手段之一。強(qiáng)力旋壓過(guò)程中金屬產(chǎn)生劇烈的塑性流動(dòng),形成特定變形織構(gòu),從而影響到旋壓件的力學(xué)性能。本文將以經(jīng)過(guò)退火處理的擠壓無(wú)縫3A21鋁合金管材,進(jìn)行多道次單向及交叉旋壓實(shí)驗(yàn),并進(jìn)行筒形件的力學(xué)性能和旋壓織構(gòu)研究;采用ABAQUS對(duì)筒形件旋壓過(guò)程進(jìn)行相應(yīng)的有限元模擬,并利用用戶(hù)材料子程序VUMAT提取旋壓筒形件的變形歷史,然后再通過(guò)UMAT實(shí)現(xiàn)率相關(guān)的晶體塑性本構(gòu)關(guān)系,建立多晶體模型,通過(guò)擬合簡(jiǎn)單壓縮應(yīng)力應(yīng)變曲線確定室溫3A21鋁合金的滑移系剪切變形參數(shù),將提取的變形梯度歷史并加載到多晶體模型上,基于晶體塑性理論,實(shí)現(xiàn)室溫3A21鋁合金筒形件多道次不同方式旋壓變形織構(gòu)的模擬。進(jìn)行模擬織構(gòu)與實(shí)測(cè)織構(gòu)的比較。進(jìn)行多道次旋壓實(shí)驗(yàn)后,觀察旋壓件微觀組織的演化:多道次旋壓過(guò)程中少量第二相始終彌散分布在晶界處,其含量不影響晶體學(xué)織構(gòu)的統(tǒng)計(jì)。當(dāng)旋壓到第2道次后,晶粒在ND方向近似于均勻分布,晶粒沿RD方向和TD方向等比例拉長(zhǎng)。從第4道次到低8道次,晶粒主要沿著RD方向伸長(zhǎng)形成長(zhǎng)條狀的晶粒,沿TD方向也存在一定的拉長(zhǎng),隨著晶粒的細(xì)化形成纖維狀;從力學(xué)性能變化規(guī)律來(lái)看,對(duì)于交叉旋壓,旋壓件環(huán)向壓縮屈服強(qiáng)度要高于軸向壓縮屈服強(qiáng)度,旋壓件環(huán)向抗拉強(qiáng)度與軸向抗拉強(qiáng)度并沒(méi)有產(chǎn)生太大的差距,環(huán)向抗拉強(qiáng)度略高于軸向抗拉強(qiáng)度�？芍徊嫘龎合鄬�(duì)于單向旋壓,有效調(diào)控了晶粒取向,提高了筒形件變形抗力。通過(guò)對(duì)3A21鋁合金筒形件多道次單向與交叉旋壓變形三維有限元模擬,分析筒形件旋壓后的外表面和軸截面的應(yīng)力應(yīng)變分布,發(fā)現(xiàn)筒形件旋壓由于局部加載和變形周期性疊加的特點(diǎn),筒形件旋壓變形使材料承受方向不斷變化的拉伸、壓縮和剪切的復(fù)合變形。對(duì)比多道次旋壓有限元模擬獲得的模擬織構(gòu)與實(shí)測(cè)織構(gòu),分析旋壓晶粒取向演化規(guī)律:變形開(kāi)始時(shí),單向與交叉旋壓的晶體取向形成明顯{110}112織構(gòu),隨著減薄率的增加,晶粒取向逐漸靠近難變形相位,到第4、6、8道次,金屬取向不再是單一的織構(gòu),而是逐漸形成{110}112、{112}111、{123}634等類(lèi)型的織構(gòu)。我們還發(fā)現(xiàn),在同一變形量下,材料的織構(gòu)類(lèi)型近似等同,單向旋壓的織構(gòu)分布較交叉旋壓相對(duì)彌散,相對(duì)交叉旋壓強(qiáng)度較低,因此交叉旋壓具有較好的調(diào)控晶粒取向的作用,提高了筒形件變形抗力。
[Abstract]:Cylinder spinning is a typical local loading forming process, which has the advantages of saving material, good formability, simple tooling and so on. It is an effective method for manufacturing large thin-walled seamless cylindrical parts. It has been widely used in aerospace, aviation and weapons. As the process of spinning deformation is very complex and there are many influencing factors, up to now, a lot of research work on spinning technology is still focused on parts forming, spinning defects and geometric precision control, etc. The control of mechanical properties of parts is less considered. The crystallographic texture can have a significant effect on the mechanical properties of metal materials. Texture has become one of the most important means to control the mechanical properties of materials. In order to affect the mechanical properties of spinning parts, this paper will carry out multi-pass unidirectional and cross-spinning experiments with annealed seamless 3A21 aluminum alloy tubes, and study the mechanical properties and spinning texture of cylindrical parts. The ABAQUS is used to simulate the spinning process of the cylinder, and the deformation history of the spinning cylinder is extracted by the user material subroutine VUMAT, and then the polycrystalline model is established by using the constitutive relation of crystal plasticity related to the realization rate of UMAT. The slip system shear deformation parameters of room temperature 3A21 aluminum alloy were determined by fitting the simple compression stress-strain curve. The extracted deformation gradient history was loaded into the polycrystalline model and based on the theory of crystal plasticity. The simulation of multi-pass deformation texture of room temperature 3A21 aluminum alloy cylinder is realized. The comparison between the simulated texture and the measured texture is carried out. After the multi-pass spinning experiment, The microstructure evolution of spinning parts is observed: a small amount of second phase is distributed at grain boundaries throughout the multi-pass spinning process, and its content does not affect the statistics of crystallographic texture. When spinning to the second pass, the grain distribution is approximately uniform in ND direction. From the 4th pass to the low 8 pass, the grains are mainly elongated along the Rd direction and elongated along the TD direction, forming fibrous with the refinement of the grains. According to the law of mechanical properties, for cross spinning, the yield strength of annular compression is higher than that of axial compression, and there is not much difference between the annular tensile strength and axial tensile strength. The circumferential tensile strength is slightly higher than the axial tensile strength. The deformation resistance of the cylindrical part is improved. The stress and strain distribution of the outer surface and axial section of the cylindrical part after spinning is analyzed by simulating the multi-pass unidirectional and cross-spinning deformation of the 3A21 aluminum alloy tube by three dimensional finite element method. It is found that due to the characteristic of local loading and periodic superposition of deformation, the spinning deformation of the cylindrical part makes the material endure the continuously changing tensile direction. Compression and shear composite deformation. Compared with the simulated texture obtained by multi-pass spinning finite element simulation and the measured texture, the evolution law of spinning grain orientation was analyzed: at the beginning of deformation, the crystal orientation of unidirectional and cross-spinning formed obvious {110} 112 texture. With the increase of thinning rate, the grain orientation is closer to the difficult deformation phase. At the 4th pass, the metal orientation is no longer a single texture, but gradually forms {110} 112, {112} 111, {123} 634 and other types of texture. We also find that under the same deformation amount, the grain orientation is not only a single texture, but also forms a texture of {110} 112, {112} 111, {123} 634 and so on. The texture type of the material is approximately the same, and the texture distribution of unidirectional spinning is relatively dispersed and the relative cross spinning strength is lower than that of cross spinning. Therefore, cross spinning has a better effect on regulating grain orientation and improving the deformation resistance of cylindrical parts.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TG306

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