AZ31B镁合金板径向推力充液拉深试验

镁合金板冷成形性能差,采用液压成形的方法可提高其冷成形性能。对AZ31B镁合金板进行径向推力充液拉深试验,分析液压力大小、模具尺寸和坯料尺寸对最大拉深高度的影响规律,并对液压拉深件破裂位置、裂纹走向及裂纹形态进行分析。研究结果表明,当凸模圆角半径较大时,随着液压力的增大,得到的最大拉深高度也大;凸模圆角半径较小时,仅有当液压力大小合适时,才能改善其成形性能;板坯直径越大,最大拉深高度就越小。破裂位置一般在拉深试件的底部圆角、凸缘和侧壁处,且裂纹走向、裂纹断面呈现不同的形态。     

镁合金AZ31B板材热拉深成形工艺参数优化

在不同温度、不同压边力和不同拉深速度下，针对厚度为0．8mm的AZ31B镁合金板材的成形性能用有限元分析软件进行模拟与分析。在25～220℃的温度范围内，采用直径为140mm的坯料进行冲压成形，研究成形温度、拉深速度以及压边力对AZ31B镁合金板成形性能的影响。结果表明：成形温度为200℃时的极限拉深比达到了2.8；成形温度在200℃以下时，随着成形温度的升高。镁合金板材的成形性能越来越好。这证明AZ31B镁合金具有良好的热拉深性能；此外，拉深速度和压边力对AZ31B镁合金的拉深成形也有重要影响。     

镁合金拼焊板拉深成形焊缝移动规律

采用有限元数值模拟软件对镁合金拼焊板拉深成形时焊缝移动规律进行了数值分析,建立了镁合金拼焊板筒形件拉深成形有限元模型.对AZ31与AZ80镁合金拼焊板拉深成形进行了数值模拟,分析了压边力及变形温度对焊缝移动规律的影响,得到了筒形件底部及侧壁法兰处焊缝的移动规律.结果表明,筒形件底部焊缝向AZ80侧移动,法兰及侧壁处向AZ31侧移动.模拟结果与试验结果吻合较好,镁合金拼焊板拉深成形时焊缝移动可以通过非均匀压边力或非均匀温度场来控制.     

镁合金方形件液压拉深成形的数值模拟

采用Dynaform有限元软件对AZ31B镁合金方形件的液压拉深过程进行数值模拟,研究了分块压边条件下,压边力加载方式、拉深速度、液压力等工艺参数对镁合金方形件壁厚差值和最小壁厚值的影响规律,并分析了方形件的壁厚分布特点.结果表明:镁合金方形件分块压边液压拉深过程中,当圆角块和直边块初始压边力分别为3和1kN,压力增幅△Q为500 N,且均采用“增-恒-减”加载方式,液压力取12 MPa,拉深速度为3000mm·s-1时,可以获得较好的成形效果;拉深后期,压边力大小不断增大或保持不变对镁合金方形件成形效果的影响程度基本一致;液压力大小对镁合金方形件的壁厚极值分布位置影响较小.     

镁合金方形件液压拉深成形的数值模拟

采用Dynaform有限元软件对AZ31B镁合金方形件的液压拉深过程进行数值模拟,研究了分块压边条件下,压边力加载方式、拉深速度、液压力等工艺参数对镁合金方形件壁厚差值和最小壁厚值的影响规律,并分析了方形件的壁厚分布特点。结果表明:镁合金方形件分块压边液压拉深过程中,当圆角块和直边块初始压边力分别为3和1kN,压力增幅ΔQ为500N,且均采用"增-恒-减"加载方式,液压力取12MPa,拉深速度为3000mm.s-1时,可以获得较好的成形效果;拉深后期,压边力大小不断增大或保持不变对镁合金方形件成形效果的影响程度基本一致;液压力大小对镁合金方形件的壁厚极值分布位置影响较小。     

AZ31镁合金板的热拉深性能

通过热轧工艺制备了厚度为0.8 mm的AZ31镁合金薄板. 在不同温度和应变速率条件下进行了单向拉伸试验. 在50～240 ℃的温度范围内, 采用平底杯形冲头拉深试验研究了成形温度、拉深速度以及冲头温度对AZ31镁合金板热拉深工艺的影响. 结果表明 AZ31镁合金热轧薄板的RLD随温度的升高而明显增大; 在成形温度为200 ℃, 拉深速度为30 mm/min的条件下, 最大RLD可达2.65, 相应的高径比为1.4, 证明AZ31镁合金板具有良好的热拉深性能; 此外, 拉深速度和冲头温度对AZ31镁合金的拉深成形也有重要影响.     

镁合金筒形件压力润滑拉深壁厚分析

通过对室温下AZ31B板筒形件压力润滑拉深的成形过程数值模拟分析,研究了内压力、压边力和凸模圆角半径等工艺参数对成形件壁厚差的影响.通过分析比较镁合金普通拉深和压力润滑拉深的成形效果,研究了成形件的壁厚分布情况.     

镁合金板材的固体颗粒介质拉深工艺参数

提出基于固体颗粒介质成形(SGMF)工艺的镁合金板材差温拉深工艺,并展开试验研究。通过对AZ31B镁合金薄板进行差温拉深成形试验,研究了成形温度、拉深速度、压边力、压边间隙、凹模圆角和润滑条件对拉深性能的影响,确定AZ31B镁合金板料最佳成形工艺参数。结果表明:该工艺可显著提高镁合金板材的成形性能,成形温度及拉深速度对板料拉深性能影响较大,板料最佳成形温度区间为290～310℃,颗粒介质与板料理想温差为110～150℃;压边力和压边间隙对拉深性能产生联合影响;此外,凹模圆角和润滑条件也对拉深性能有一定的影响。当上述工艺参数达到最佳值时成功拉深出极限拉深比(LDR)为2.41的工件。     

基于DEM-FEM的AZ31B板材软模成形极限预测

针对金属板材固体颗粒介质成形工艺中散体颗粒的离散性能和板材连续变形特点,提出并构建离散元-有限元耦合仿真模型。通过试验和数值模拟相结合的方法,建立镁合金板材温热成形韧性破裂准则,并验证该准则的有效性。最后结合韧性断裂准则对AZ31B镁合金固体颗粒介质筒形件温热拉深进行离散元-有限元耦合模拟,对其成形极限进行预测分析,并展开相应条件下的拉深成形试验。结果表明:基于韧性断裂准则的离散元-有限元耦合分析方法可以有效预测镁合金板固体颗粒介质温热拉深成形极限。     

AZ31及ZE10镁合金板拉胀复合成形的研究

对AZ31及ZE10镁合金板在20．300℃条件下进行了力学性能、弯曲及锥杯试验。研究结果表明：随着变形温度升高，镁合金板材强度下降而塑性、弯曲性能、“拉深＋胀形”复合成形性能明显改善。ZE10镁合金板比AZ31镁合金板具有更好的弯曲及拉胀复合成形性能。200℃、250℃试验时，ZE10镁合金锥杯试样可顺利拉深进入锥杯底部圆孔而不出现裂纹。     

Deep drawing of square cups with magnesium alloy AZ31 sheets

The square cup drawing of magnesium alloy AZ31 (aluminum 3%, zinc 1%) sheets was studied by both the experimental approach and the finite element analysis. The mechanical properties of AZ31 sheets at various forming temperatures were first obtained from the tensile tests and the forming limit tests. The test results indicate that AZ31 sheets exhibit poor formability at room temperature, but the formability could be improved significantly at elevated temperatures up to 200 °C. The test results were then employed in the finite element simulations to investigate the effects of process parameters, such as punch and die corner radii, and forming temperature, on the formability of square cup drawing with AZ31 sheets. In order to validate the finite element analysis, the deep drawing of square cups of AZ31 sheets at elevated temperatures was also performed. The experimental data show a good agreement with the simulation results, and the optimal forming temperature, punch radius and die corner radius were then determined for the square cup drawing of AZ31 sheets.     

Formability of AZ31 magnesium alloy sheets at warm working conditions

Fine-grained AZ31 magnesium alloy sheets were prepared through hot-rolling process. To investigate the mechanical properties of the sheets, uniaxial tensile tests were conducted at various temperatures and strain rates. The formability of AZ31 alloy sheets at warm working conditions was evaluated by limit drawing ratio (LDR) tests and limit dome height (LDH) tests at temperatures from 50 to 240 °C. It is demonstrated that LDR increases remarkably with temperatures, whilst LDH does not seem to increase much with temperatures. The maximum LDR reaches 2.65 at a punch speed of 30mm/min at 200 °C, whereas the maximum LDH is only 10.8 mm, showing good deep drawability and poor stretchability of AZ31 alloy sheets. In addition, punch speeds and punch temperatures were found to have significant effects on the deep drawability of AZ31 magnesium alloy sheets.     

Influence of initial texture on formability of AZ31B magnesium alloy sheets at different temperatures

Repeated unidirectional bending (RUB) process was carried out to improve the texture of AZ31B magnesium alloy sheets. Influence of initial texture on formability of AZ31B magnesium alloy sheets at different temperatures was investigated. Compared with the as-received sheets, the limiting drawing ratio of the RUB processed sheets increased to 1.3 at room temperature, 1.5 at 50 °C and 1.7 at 100 °C, respectively. The improvement of the press formability at lower temperatures can be attributed to the texture modification, which led to a smaller Lankford value and a larger strain hardening exponent. However, the press formability of the sheet with a weakened basal texture has no advantage at higher temperature. This is due to much smaller r-value that results in severe thinning in thickness direction during the stamping process which is unfavorable to forming. Anyhow it is likely that the texture control has more effect on the press formability at lower temperature.     

镁合金方形件分块压边液压拉深壁厚分析

基于分块压边液压成形装置,运用Dynaform有限元软件对AZ31B镁合金方形件的液压成形过程进行了数值模拟。比较分析了镁合金板在整体式压边和分块式压边条件下的液压成形效果,重点研究了分块压边方式对镁合金方形件的壁厚影响规律,并探索了相对合理的压边力参数。研究结果表明:与整体式压边相比,采用分块式压边能有效改善AZ31B镁合金方形件的壁厚均匀性,提高其成形质量。     

AZ31镁合金薄板手机外壳温冲模具设计及成形性能研究

设计并制造了AZ31镁合金薄板的手机外壳温冲模具,并对其成形性能进行试验研究。试验表明,eta/DYNAFORM有限元模拟软件能够较好的验证模具设计的合理性和分析AZ31镁合金薄板冲压成形性能,通过合理地选取模具参数,并对拉伸速度、润滑条件、坯料以及凸、凹模温度等主要影响因素的控制,可有效地解决AZ31镁合金拉伸生产过程中的拉裂缺陷,在普通液压机上能成功冲压出镁合金壳形件。     

Evaluation and prediction of the forming limit of AZ31B magnesium alloy sheets in a cross-shaped cup deep drawing process

In this study, the formability of AZ31B magnesium alloy sheets was investigated through experimental and numerical approaches. Tensile tests and limit dome height tests were carried out at several temperatures between 25 °C and 300 °C to obtain the mechanical properties and forming limit diagram (FLD). The interfacial heat transfer coefficient between two adjacent tools, and the convection coefficient were estimated by comparing the tool temperatures obtained from trial heat transfer analyses with actual measured data. The FLD-based criterion considering the strain path and the blank temperature was used to predict by finite element analysis (FEA) the forming limit in a cross-shaped cup deep drawing process. A comparison of the FEA and experimental data showed that this criterion was very useful and reasonable. In particular, the temperature of each forming tool that provided the best formability of AZ31 sheets was determined by coupled temperature-deformation analyses. A practical method that can greatly reduce the forming time by increasing the punch speed during the forming process was suggested.     

轧制工艺对AZ31B镁合金薄板组织与性能的影响

研究了轧制温度和轧制速度对AZ31B镁合金薄板微观组织演变和力学性能的影响。结果表明,轧辊加热有利于镁合金薄板成型;AZ31B镁合金在低温或低速轧制时薄板纵向组织为大量的切变带,切变带区域包含大量孪晶组织,横向组织为含极少量孪晶的等轴晶组织;在轧制温度为400℃和轧制速度为16m/min轧制时,由于动态再结晶,横纵截面组织均为等轴晶。AZ31镁合金薄板的最佳轧制制度为轧辊温度为70℃、轧制温度为400℃、轧制速度为6m/min,此工艺轧制的薄板横向抗拉强度、屈服强度和伸长率分别为350MPa、300MPa和12%,纵向为345MPa、290MPa和11.2%,纵向与横向性能差别明显减小。     

AZ31B变形镁合金压力成形

总结了AZ31B变形镁合金挤压、轧制和热冲压拉深的研究工作。AZ31B挤压板材无裂纹、无烧损,其组织呈晶粒细小的等轴晶;用分流挤压铝合金技术可生产挤压比不大于45,厚度不小于1 5mm的非薄壁镁合金管材;交叉轧制的镁合金薄板的A显著提高,Rp0.2和Rm明显下降;单向轧制时,则出现相反的结果。采用机械冲压法成功地热冲压出60mm×60mm×20mm的方形件,无裂纹现象。     

Cold stamping for AZ31B magnesium alloy sheet of cell phone house

Electric product house of magnesium alloy sheet is usually obtained by warm stamping owing to its poor plasticity and formability at room temperature. The formability of AZ31B magnesium alloy sheet can be improved by repeated unidirectional bending (RUB) process through control of (0002) basal texture. Compared with as-received sheet, the Erichsen value (IE) of the sheet underwent RUB process increases to 5.90 from 3.53 at room temperature. It is also confirmed that cell phone houses could be stamped successfully in crank press with AZ31B magnesium alloy sheets underwent RUB process. It provides an alternative to the electronics industry in the application of magnesium alloys.