利用织构系数预测正交铝板拉深制耳倾向

圆形铝板拉深过程中的制耳现象造成原材料的极大浪费,板材中存在的织构造成板面塑性各向异性,从而造成了制耳现象。改变各种织构组分的体积比,使晶粒取向分布趋于均匀,可以降低板材的制耳率。用织构组分体积比只能粗略地描述板材的晶粒取向分布,而织构系数则能更准确地描述板材内的晶粒取向分布。文章假设铝板法兰区承受均匀的环向、径向应力,各个方向上的径向应变与晶粒取向有关。并根据晶粒取向分布函数的对称性,得到了织构系数与制耳倾向之间的关系。     

异步轧制对3004铝合金变形织构及制耳率的影响

以３００４铝合金为实验材料，研究了异步轧制对该合金的变形织构以及相应的制耳率的影响。实验表明：异步轧制和同步轧制板的主要变形织构是相同的，均为纯铜型织构｛１１２｝＜１１１＞＋｛２１３｝＜３６４＞＋｛１１０｝＜１１２＞，但异步轧制产生的变形织构较同步轧制的强度高，且随异步轧制速比的提高而增强。同时，异步轧制的板材中还出现｛００１｝＜１１０＞织构。另外，在相同压下率的情况下，异步轧制板材的深冲制耳率均大于同步轧制的制耳率     

Earing behavior and crystallographic texture of aluminum alloys during cold rolling

Earing behavior and crystallographic texture during cold rolling have been investigated for two commercial can body aluminum alloys. It is found that earing behavior can be inferred from texture information. The recrystallization texture causes 90° earing, while the deformation texture results in 45° earing. A strong recrystallization texture (or a high 90° earing) of a hot band causes a later appearance of lower 45° earing in the final gauge sheet and thus is desirable for industry. The earing behavior is better indicated by the delta function, which is characterized as the intensity difference between the deformation texture and the softening texture. The results indicate that the earing behavior during cold rolling can be quantitatively monitored by the crystallographic texture. In addition, effects of the texture inhomogeneity through-thickness have also been investigated and discussed.     

Comparison of earing behavior between continuous cast and direct chill cast AA 5182 aluminum alloys during cold rolling and annealing

The evolution of texture and earing during rolling of continuous cast (CC) and direct chill (DC) cast AA 5182 aluminum alloys was investigated. The results showed that the CC alloy possessed a significantly weaker cube texture than the DC alloy after annealing at 454 °C for 3 h. The evolution of texture and earing during rolling was strongly affected by the initial texture. The 45° earing value of the CC alloy increased with increasing rolling reduction, while the 0/90° earing value of the DC alloy decreased. After 45% cold rolling reduction, the deep-drawn cup of the DC alloy exhibited eight ears at 0°, 45° and 90° to the rolling direction. The DC sheet with minimum earing was obtained at about 83% rolling reduction. The evolution of texture and earing during annealing of the CC and DC alloys was compared. An empirical relationship between the earing value and texture volume fractions was established. Minimization of earing could be achieved by balancing the cube, r-cube and β fiber components.     

Textures in high purity aluminum foils and AA3004 sheets

1　INTRODUCTIONWithincreasingdemandsofhighmaterials properties ,thetexturesinAlandAlalloysplaymoreandmoreimportantrole .Highpurityaluminumfoilsneedverystrongcubetexture ,whichwillfavorthe“channeletching”effectforhighvoltageelectrolyticcapacitors ,andAA30 0 4aluminumalloysheetsneedcertaincubetexturetosuppressthe 4 5°earingbehav iorresultingfromstrongrollingtexturecompo nents[1] .InAlandAlalloys ,heavycoldrollingwillresultinstrongβ fibertexturescomposedofthewellknownCu ({ 112 }〈111〉…     

Texture-based design of a convoluted cut-edge for earing-free beverage cans

A texture-based earing model is applied to minimize earing of a 25 cl aluminium beverage can. Earing of can body stock was simulated by means of a polycrystal-plasticity model from the crystallographic texture of the sheet. The simulated earing profile was used to devise an optimized blank shape with minimum earing for the designated can geometry, and a convoluted cut-edge was produced accordingly. The earing patterns of the resulting intermediate cups and final cans were compared with their counterparts produced with a conventional round tool, demonstrating that the optimized blank shape quite efficiently reduced earing. The underlying assumption that an earing-free cup will actually lead to an earing-free can is discussed.     

3104铝合金薄板深冲制耳的有限元模拟

采用由板材织构信息进行加权的CMTP屈服函数并考虑了摩擦和压边力的变化对3104铝合金薄板的深冲制耳进行了有限元模拟；并与采用Barlat(1991)屈服函数的预测值及实测值进行了比较；分析了深冲过程中圆片的厚度变化规律；讨论了进一步提高预测精度需考虑的因素。结果表明：采用CMTP屈服函数模拟的制耳轮廓与实测值比较吻合，随摩擦和压边力的增加，制耳轮廓高度也增加；且比采用Barlat(1991)屈服函数模拟的精度要高。模拟深冲过程中圆片厚度的变化规律与实际情况一致。     

薄板制耳性能评价方法的探讨

主要对制耳率及其计算方法进行了探讨,指出了现有制耳率公式在某些制耳情况下存在评价不充分的不足,并对制耳率计算公式进行了新的探讨。传统的制耳率公式着重考虑了制耳峰及制耳谷的平均高度,但对制耳峰及制耳谷的宽度及面积情况反映不充分。在实际生产中,制耳现象对深冲材料的利用率影响很大。从实际出发,侧重于制耳评价方法对深冲材料裁边面积及材料利用率的反映,对制耳率计算公式进行了新的探讨。与传统制耳率公式相比较,该新公式可以弥补传统公式的不足,形成优势互补。     

INFLUENCE OF STRESS STATE IN EARING PREDICTION (Ⅱ) CRYSTALLOGRAPHIC ANALYSIS OF BCC METALS

ＩＮＦＬＵＥＮＣＥＯＦＳＴＲＥＳＳＳＴＡＴＥＩＮＥＡＲＩＮＧＰＲＥＤＩＣＴＩＯＮ（Ⅱ）ＣＲＹＳＴＡＬＬＯＧＲＡＰＨＩＣＡＮＡＬＹＳＩＳＯＦＢＣＣＭＥＴＡＬＳ①ＬｉＳａｉｙｉ，ＺｈａｎｇＸｉｎｍｉｎｇ，ＬｉＬｕｏｘｉｎｇＤｅｐａｒｔｍｅｎｔｏｆＭａｔ...     

The numerical analysis of anisotropic sheet metals in deep-drawing processes

Flange earing of strong anisotropic sheet metals in the deep-drawing process is analyzed numerically by the elastic–plastic large deformation finite element formulation based on the discrete Kirchhoff triangle plate shell element model. A Barlat–Lian anisotropy yield function and a quasi-flow corner theory are introduced in the present formulation. The numerical results are compared with the experimental results of the cylindrical cup drawing process. The focus of the present research is on the numerical analysis and the constraining scheme of the flange earing of circular sheets with strong anisotropy in the square cup drawing process.     

Mechanical anisotropy and deep drawing behaviour of AZ31 and ZE10 magnesium alloy sheets

The influence of the initial microstructure on the deep drawability and the associated microstructural evolution in two different magnesium alloy sheets, AZ31 and ZE10, has been examined. Tensile testing at room temperature shows that the AZ31 sheet has high plastic strain ratios, r = 2–3, which are caused by strong basal-type texture. The ZE10 sheet shows lower r values, r ～ 1, as a result of its weak texture. Deep drawing experiments carried out over the temperature range 100–300 °C revealed that the ZE10 sheet can be successfully deep-drawn at lower temperatures than the AZ31 sheet. The ZE10 cups show earing despite the weak texture and low normal anisotropy, while earing of the AZ31 cups is negligible. In the ZE10 cups, deformation is accommodated mainly by 〈a〉 slips and by compression as well as secondary twinning. The occurrence of dynamic recrystallization is observed in successfully deep-drawn AZ31 cups.     

Simulation of sheet metal forming incorporating EBSD data

In this work, a ferritic stainless steel (DC04) is investigated numerically on the micro and the macro scale. Single crystal orientations extracted from 2D electron backscatter diffraction (EBSD) data are reduced by using two methodically different methods. Based on these reduced data sets, a two-scale Taylor type model is applied at the integration points of the finite elements to simulate a deep drawing process. The earing profiles of the simulated cups are compared to the experimental data. In addition, the influence of the variation of the sheet holder force on the earing profile of the drawn cup for different friction coefficients is discussed. It is found that incorporating experimental microstructural information in the two-scale simulations, realistic earing profiles are obtained. With regard to efficient computation, a coarse FE model is used, resulting in a larger average cup height than the experimental slope. Nevertheless, reducing the friction coefficient in the model, the slope of the cup height agrees very well with the experiments which is expected to be obtainable for a finer FE mesh and the experimental friction coefficient as well.     

紫铜带材性能与杯形件制耳的关系

通过对紫铜带材的性能与拉深试验,分析、介绍了材料的性能与各向异性对拉深杯形件制耳的影响,以及消除制耳的一般方法。     

纯钛板材冷拉成形过程中的微观组织与织构演变(英文)

研究纯钛板材冷拉成形过程中微观组织及织构演化规律。半球形壳体件在深拉延过程中由于各部位变形模式及应变形式的不同会形成胀形区、拉深区及法兰区等3个区域。结果表明,在拉深件的3个区域中塑性应变均由位错滑移与变形孪晶共同作用。纯钛板材及其拉深件中的织构包含轧制织构与再结晶织构。由于变形孪晶与位错滑移对织构的影响规律不同,初始板材织构的强度及类型在深拉过程中不断变化。变形孪晶对初始织构具有弱化作用,特别是对于再结晶织构,这种弱化效应更为明显。由于拉深区产生的孪晶较多,再结晶织构消失。此外,大拉伸变形时位错滑移为主导机制,织构强化效应明显。     

INFLUENCE OF STRESS STATE ON EARING BEHAVIOR──（Ⅰ） CRYSTALLOGRAPHIC ANALYSIS OF FCC METALS

ＩＮＦＬＵＥＮＣＥＯＦＳＴＲＥＳＳＳＴＡＴＥＯＮＥＡＲＩＮＧＢＥＨＡＶＩＯＲ──（Ⅰ）ＣＲＹＳＴＡＬＬＯＧＲＡＰＨＩＣＡＮＡＬＹＳＩＳＯＦＦＣＣＭＥＴＡＬＳ￥ＬｉＳａｉｙｉ；ＺｈａｎｇＸｉｎｍｉｎｇ；ＬｉＬｕｏｘｉｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔ...     

Warm deep-drawing and post drawing analysis of two Al–Mg–Si alloys

The increasing use of aluminium alloys in light weight structural applications is restricted mainly due to their lower room temperature formability compared to steels. Forming at higher temperature is seen as a promising solution to this problem. In the present investigation two Al–Mg–Si alloys (EN AW-6016 and EN AW-6061) were deep-drawn at room temperature and 250 °C and their behaviour during drawing were compared. The effect of ram speed, drawing ratio, holding time, and temper was also investigated. Among the parameters investigated temperature was found to have the most significant effect on the force–displacement response. Because anisotropy has been an important concern during the deep-drawing process, this parameter was also investigated by looking at the earing profile. With increasing temperature the amplitude of earing decreased while the number of ears remained the same, indicating that there is no change in anisotropy with temperature. The cup thickness increases from the bottom of the cup to the flange with a local minimum around the mid-height of the wall.     

Through-process simulation of texture and properties during the thermomechanical processing of aluminium sheets

Computer-based alloy and process development requires the integration of models for simulating the evolution of microstructure, microchemistry and crystallographic texture into process models of the thermomechanical production of Al sheet. In this paper, a softening model simulating the progress of recovery and recrystallization and the following texture changes is linked to deformation and microchemistry models. The possibility of such coupled simulations is illustrated by way of the thermomechanical processing of Al–Mn–Mg AA 3104 can stock. In particular, the impact of inter-stand recrystallization between the tandem hot rolling passes as well as recrystallization during coil cooling (“self-annealing”) on the resulting hot strip and final gauge textures are explored. Finally, the predicted textures are input into a polycrystal–plasticity model to simulate anisotropic properties (earing behaviour) of the sheets. Thus, it is possible to link the materials properties at final gauge to the decisive steps of deformation and recrystallization along the thermomechanical process chain.     

Numerical study of influence of anisotropy on flanging earing based on Barlat six—component yield function

The anisotropy of stamped sheet metal exerts evident effects on the formability.Barlat six-component yield function was introduced into the elastoplastic ficite element formulation based on the principle of virtual veloci-ty and the discrete Kirchhoff triangular element model.The flanging earing in cylindrical cup drawing process of cir-cular sheet metal was numerically simulated.The influence of anisotropy on the forming process was studied.     

一种预测织构板材制耳倾向的新方法

提出了一种根据板材晶体学织构预测深中制耳行为的新方法，预测了立方金属板中重要织构组分的制耳倾向类型及相对大小，结果优于传统的晶体学方法，可用于抑制深冲制耳的织构平衡设计。     

Evolution of through-thickness texture gradients in various steel sheets

In order to investigate the evolution of through-thickness texture gradients in various ferritic steel sheets, samples of a deep drawing steel, a ferritic stainless steel and a low carbon steel were deformed by cold rolling with and without application of a lubricant during the deformation process. The hot band texture of all samples examined showed notable through-thickness texture gradients. The evolution of the cold rolling texture in the ferritic stainless steel and the low carbon steel in a solution-treated state was nearly independent of the lubrication during rolling. However, in the deep drawing steel and the as-received low carbon steel, the lubrication played an important role in the formation of the through-thickness texture gradients. Whereas the samples rolled with lubrication showed uniform textures throughout the sheet thickness, in the samples rolled without lubrication pronounced shear textures were observed on the sheet surface. The evolution of these through-thickness texture gradients is discussed in terms of inhomogeneous strain states computed by an FEM model. This article is based on a presentation made in the symposium “ ’99 International Symposium on Textures of Materials”, held at Sunchun National University, Sunchun, April 21–22, 1999 under the auspices of The Korean Institute of Metals and Materials and The Research and Development Center for Automobile’s Parts and Materials.