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。     

AZ31镁合金铸轧板材热拉深工艺研究

用拉伸试验机测试了AZ31镁合金铸轧板材的高温力学性能和直角弯曲性能,并对镁合金铸轧板材进行了热拉深试验,研究了拉深温度、拉深速率、压边间隙、润滑方式等工艺参数对板材成形性能的影响。试验结果表明,AZ31镁合金铸轧板材适合于200℃以上拉深,且最小弯曲半径小于4mm,最佳拉深工艺条件为,拉深温度225℃～275℃,拉深速率50mm/min～100mm/min,压边间隙1.125t～1.15t,采用固体润滑剂PTFE,可以得到最大极限拉深比为2.95。     

AZ31与ME20M镁合金板料热拉深性能实验研究

在不同成形温度、拉深速度、润滑条件下对1．2mm厚的AZ31镁合金板料与3mm厚的ME20M镁合金板料进行热拉深性能实验研究。实验表明：AZ31镁板的最佳成形温度为215℃，而ME20M镁板在250℃以上成形性能才随温度的升高明显改善，说明稀土元素对镁合金的室温拉深性能影响很小，但却显著提高镁合金的高温拉深性能，同时也说明镁合金板料具有较佳的轻薄结构成形性；两种镁合金板料热拉深成形性能都对拉深速度敏感．有润滑条件比无润滑条件成形性能要好。通过对成形件传力区部位金相实验分析得知，合理控制热拉深实验参数，能改善成形件微观组织，进而保证成形件质量。     

铸轧AZ31镁合金板的冲压工艺及性能

研究了变形温度、变形速度对铸轧AZ31镁合金板的极限拉深比(LDR)和组织的影响。变形温度在250~300℃之间,铸轧AZ31镁合金板的极限拉深比(LDR)可达2.5。低的变形速度有利于提高拉深性能。低温条件下,拉深变形后的组织主要为孪晶;随着温度的增加,拉深过程中发生再结晶,在晶界周围产生细小的再结晶晶粒。     

镁合金AZ31盒形件拉深成形有限元模拟分析

摘 要:利用有限元数值模拟分析了各工艺参数(拉深温度、凸模圆角半径及凹模内圆角半径)对镁合金AZ31盒形件拉深成形性能的影响,并通过实验进行了验证.结果表明:采用最佳拉深温度和最佳的凸模圆角半径、凹模内圆角半径可以有效地改善厚度为0.5mm的镁合金AZ31板材的拉深成形性能.     

AZ31镁合金板温拉深流变应力行为研究

为了建立镁合金板温拉深成形的流变应力数学模型,在温度为200℃～350℃和应变速率为0.001 s^-1～0.1s^-1的条件下,对AZ31镁合金板进行拉伸实验,研究其温拉深流变应力行为.通过对Fields-Backofen方程修正分析,建立了AZ31镁合金板温拉深流变应力数学模型,在峰值应力之前,模型预测值与实测结果相比十分接近.对加入软化因子s的模型进行了计算,与修正的Fields-Backofen相比,更好的模拟了软化阶段的流变应力变化.本文研究的模型可以用于指导镁合金板成形,也为有限元分析流变应力打下基础.     

AZ31B镁合金板热拉深成形工艺参数优化及微观组织演变

为了探索合适的工艺参数和微观组织演变,得到镁合金板热拉深成形质量最优的工艺参数组合及零件在热拉深成形时的微观组织演变规律,以厚度为1.6 mm的AZ31B镁合金为研究对象,利用正交试验法进行筒形件的热拉深成形试验。以成形温度、凸模运动速度和润滑剂种类这3个工艺参数作为影响因素,最大拉深高度和最大拉深力作为试验评价指标,建立3因素3水平的正交试验。对试验结果进行极差和方差分析,得到工艺参数对试验指标的影响主次关系与显著性影响,并对优选试验方案成形的筒形件进行了壁厚测试,综合最大拉深高度和成形质量分析得到最优工艺参数组合。最后,对零件微观组织演变规律进行了探究。结果表明,成形温度为240℃,凸模运动速度为30 mm·min^-1,润滑剂采用二硫化钼锂基脂时,筒形件拉深高度达到最大值,壁厚均匀,成形质量良好。     

AZ31镁合金复杂形状壳体拉深成形试验研究

通过拉深成形试验研究了AZ31镁合金复杂形状壳体的成形性能,分析了成形温度、拉深速度、坯料加热时间及润滑等工艺参数对镁合金手枪壳体拉深成形件质量的影响规律.结果表明,合理的成形工艺参数:成形温度为290～350 ℃,拉深速度为0.1～0.2 mm/s,加热时间为5～10 min,润滑剂采用二硫化钼和机油的混合物,成功地加工出合格的复杂形状的镁合金手枪壳体.     

AZ31镁合金板料矩形件拉深分块压边力控制

采用数值模拟和实验相结合的方法研究了AZ31镁合金板料分块压边力拉深矩形件的过程.首先设计了分块压边板,采用多点顶杆结构提供拉深所需的压边力,各个顶杆之间相互独立,可在板料不同的区域实现不同的压边力加载.然后对分块压边力拉深成型过程进行了数值模拟,研究不同板料区域动态压边力的分布规律以及板料流动性特点,通过实验验证了模拟所得规律.研究结果表明,模拟和实验具有良好的一致性,压边力的合理分布可使板料的流动更加均匀,有利于拉深性能的提升.     

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.     

异步轧制AZ31镁合金板材室温冲压性能研究

文章主要对异步轧制AZ31镁合金板材室温冲压性能进行了研究,以探讨提高镁合金板材冲压性能的途径。结果表明,异步轧制有利于板材的晶粒细化,其晶粒尺寸约为7.6μm,明显小于普通轧制板材的12.5μm;而由于异步轧制过程中剪切变形的作用,异步轧制使板材的(0002)基面晶粒取向减弱;与普通轧制相比,异步轧制板材的应变硬化能力增加,屈服强度降低,制耳参数减小,但塑性应变比也降低,这可归因于异步轧制所导致的晶粒细化和晶粒取向的改变。     

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.     

Deformation behaviors of magnesium alloy AZ31 sheet in cold deep drawing

To investigate how the popular magnesium alloy AZ31 sheet （aluminum 3%, zinc 1%） behaves in cold working, deep drawing experiments at room temperature, along with finite element（FE） simulation, were performed on the cold forming sheet of the AZ31 alloy after being annealed under various conditions. The activities were focused on the fracture pattern, limit drawing ratio（LDR）, deformation load, thickness distribution, anisotropic effect, as well as the influences of the annealing conditions and tool configuration on them. The results display that punch shoulder radius instead of die clearance, has much influence on the thickness distribution. The anisotropy is remarkable in cold working, which adversely impacts the LDR. The fracture often happens on the side wall at an angle to axis of the deformed specimen. The results also imply that the LDR for the material under present experimental conditions is 1.72, and annealing the material at 450 ℃ for 1 h may be preferable for the cold deep drawing.     

Texture evolution of extruded AZ31 magnesium alloy sheets

The evolution of texture during the annealing and hot rolling process of extruded AZ31 magnesium alloy sheets was studied. There are two kinds of texture components in the extruded AZ31 sheets. One is {0002}<1-010> and the other is {1-010}<1-120>. The {0002}<1-010>component predominates. After annealing at 723 K for 3 h, both {0002}<1-010> and {1-010}<1-120> components are strengthened moderately. This indicates that grains with both two components mentioned above grow faster than those with other orientations. The {1-010}<1-120> component disappears and the intensity of {0002}<1-010> component decreases significantly after hot rolling with a 30% reduction at 623 K. This is mainly attributed to rotational dynamic recrystallization (RDX) during the hot rolling.     

AZ31镁合金铸轧和常规轧制板的变形组织及形变特征

在变形温度为150～400 ℃、应变速率为0.3～0.000 3 s~(-1)条件下,在Gleeble1500热模拟机上采用等温拉伸试验对AZ31镁合金铸轧和常规轧制板的高温塑性及组织演变进行研究.结果表明:两种AZ31镁合金板的峰值应力和峰值应变均随着变形温度的降低和应变速率的增加而逐渐增大.铸轧板的应变硬化指数和应变速率敏感系数均大于常规轧制板的.在高温低应变速率变形条件下,铸轧板的晶界滑移引起的空洞尺寸、体积分数和密度均大于常规轧制板的.低应变速率下拉伸变形后的动态再结晶晶粒尺寸随温度的升高逐渐增加;不同变形条件下铸轧板的晶粒尺寸均小于常规轧制板的;再结晶晶粒尺寸和Z参数呈幂律关系.     

AZ31镁合金高温热压缩变形特性

在应变速率为0.005～5 s-1、变形温度为250～450℃条件下,在Gleeble-1500热模拟机上对AZ31镁合金的高温热压缩变形特性进行了研究.结果表明:材料流变应力行为和显微组织强烈受到变形温度的影响;变形温度低于350℃时,流变应力呈现幂指数关系;变形温度高于350℃时,流变应力呈现指数关系;变形过程中发生了动态再结晶且晶粒平均尺寸随变形参数的不同而改变,其自然对数与Zener-Hollomon(Z)参数的自然对数成线性关系;材料动态再结晶机制受变形机制的影响,随温度的不同而改变;低温下基面滑移和机械孪晶协调变形导致动态再结晶晶粒的产生;中温时Friedel-Escaig机理下位错的交滑移控制动态再结晶形核;高温时位错攀移控制整个动态再结晶过程.在本实验下,材料的最佳工艺条件是:变形温度350～400℃,应变速率为0.5～5 s-1.     

AZ31镁合金板材温热冲压数值模拟与实验研究

采用Gleeble3500热模拟实验机进行了单向拉伸实验,分析了AZ31镁合金板材的力学性能;以此实验数据为基础,对温热冲压过程进行了数值模拟,研究了拉深温度、压边力等工艺因素对镁合金板材成形性能的影响;通过极限拉深比实验,对数值模拟结果进行了实验验证。结果表明:在极限拉深温度150℃,极限拉深速度15 mm/s,固定压边力的工艺条件下,极限拉深比能够达到2.5。模拟结果表明:模拟结果和实验结果具有良好的一致性;采用变压边力可以明显提高板材的冲压性能,极限拉深比将达到5.0。