拉铆套冲孔成形模具磨损分析及工艺参数优化

以拉铆套四工位冷挤压成形为例,针对反向冲孔工序中冲头磨损严重现象,利用Deform-3D软件对冲孔过程进行了有限元数值模拟,并引入正交试验进行工艺参数优化。选取了摩擦因子、冲压速度、模具初始硬度、冲头圆角半径这四个主要影响模具磨损因素,设计4因素3水平的正交试验,以减少冲头磨损量为试验指标获得了最优工艺参数组合。结果表明,当摩擦因子为0.10、冲压速度为6 mm/s、模具初始硬度为70 HRC、冲头圆角半径为0.5 mm时,冲头磨损量最小。     

圆角半径及拔模斜度对钛合金T型构件局部加载过程的影响(英文)

为了研究几何参数对T型构件局部加载过程的影响,应用主应力法建立了充分考虑圆角半径、拔模斜度的新模型。实验和数值模拟结果验证表明新数学模型的结果更接近于实验和数值模拟值;拔模斜度的影响可以忽略;圆角半径的影响显著,特别是在圆角半径和筋宽的比率小于0.75的情况下更为显著。     

可调节的板料无铆钉滚压连接装置设计

针对传统的板料无铆钉连接技术需要专用的设备及模具,并且凹模结构复杂等问题,设计开发了一种简单实用的板材无铆钉滚压连接装置,该装置不需要专用的压力成形设备,通过一对凸模的旋转运动实现板料连接。通过设计合理的凸模和凹模的结构尺寸,分别对厚度为1.2 mm的Al5052铝板和厚度为1.5 mm的Al1060铝板进行了滚压连接试验,对所得的滚压试件进行断面观测试验和抗剪试验,得到相关几何参数及接头抗剪力。试验结果表明:该装置结构简单,能够实现不同厚度板料的连接,凸模旋转的垂直压下量对接头互锁值和底厚值的影响较大,对颈厚值的影响较小,合理地控制凸模旋转的垂直压下量和凸模间距可以提高接头的连接质量。     

喇叭形灯罩拉深成形有限元分析与正交优化

分析了影响喇叭形灯罩成形性能的主要因素:压边力、凸模圆角半径、板料厚度和冲压速度。借助Dynaform软件对喇叭形灯罩拉深成形进行了单因素分析,得到了合理的压边力、凸模圆角半径、板料厚度和冲压速度的取值范围。采用正交试验方法对以上因素进行了多因素的正交优化分析,得到了最优的参数组合。     

基于Dynaform的6016-T4P铝合金汽车机舱盖模面优化

以Dynaform 5. 9软件为平台,对某车型6016-T4P铝合金机舱盖外覆盖件进行全工序冲压成形数值模拟及模面结构参数优化。通过设计5因素4水平的正交试验,研究了凹模圆角半径、凸模圆角半径、拔模斜度、修边延长量、模面高度对机舱盖外覆盖件冲压成形的影响。在正交试验最优结构参数组合的基础上,结合模面补偿技术,研究了回弹量随补偿因子的变化趋势。模拟结果表明:拔模斜度对最大减薄率影响较大,凹模圆角半径对最大主应变影响较大,修边延长量对回弹量影响较大。当补偿因子取1. 0时,回弹补偿效果最好。经成形试验,得到了合格的产品,验证了模拟的正确性。     

阶梯盒件拉深成形有限元分析与正交优化

分析了影响阶梯盒件成形性能的主要因素:压边力、拉延速度、凹模圆角半径以及阶梯转角。通过Dynaform软件对阶梯盒件拉深成形进行了单因素分析,得到了合理的压边力、拉延速度、凹模圆角半径以及阶梯转角取值范围。采用正交试验法对以上因素进行了多因素的正交优化分析,得到了最优的参数组合。     

某档位齿轮坯精锻成形模具结构参数的数值模拟分析及优化

针对某档位齿轮坯在闭式精锻成形过程中径向筋部出现的充填不饱满和折叠的缺陷,为了优化金属的流动性,改善筋部的填充情况,获得性能优良的合格锻件,运用正交实验和有限元结合的方法,分析了模具筋部拔模斜度α、圆角半径R对成形过程的影响,得出了极限模具结构参数图。分析了不同区域模具结构参数对成形质量的影响,确定在区域D中的参数条件下,锻件无明显的充不满和折叠缺陷,并优选拔模斜度为1.3°、圆角半径为3 mm进行了实际生产验证。研究结果表明:锻件质量良好,筋部端面平整,底部无折叠缺陷,实际锻件与数值模拟结果相吻合。     

前防撞梁拉延成形过程分析及工艺参数优化

采用Dynaform软件对某汽车前防撞梁成形过程进行了模拟,分析了不同形式的工艺补充面对零件成形的影响,以减薄率为评价标准,最终选取凸模圆角半径25 mm、凹模圆角半径15 mm的两端补充形式和符合零件形状的非平面压料面.采用正交试验法研究了压边力、冲压速度、摩擦因数和模具间隙4个工艺参数对成形结果的影响,获得了工艺参...     

失效铝合金平底无铆连接接头的原位固相修复方法（英文）

为了修复失效平底无铆连接接头并提高其力学性能，提出一种原位固相修复方法。通过对比研究平底无铆连接接头和修复接头的显微组织、力学性能和断裂失效行为，验证修复方法的可行性和有效性。结果表明，失效平底无铆连接接头的断裂颈部被成功地原位修复。焊核的显微组织被充分细化，使得修复接头的力学性能得到提升。转速和持续加热时间对修复接头的力学性能起着至关重要的作用。与平底无铆连接接头相比，冶金结合使修复接头的力学性能得到加强。修复接头的最大拉剪强度提高了409.90%，最大断裂伸长量提高了68.92%。断裂失效行为表明，修复接头的强度明显高于原始平底无铆连接接头，这说明失效平底无铆连接接头的修复方法是可行有效的。     

圆筒拉深件形状与厚度变化数值模拟分析

借助Dynaform软件,模拟分析了在不同拉深凹模圆角半径情况下,模具间隙及压边力等工艺参数对直壁圆筒拉深件外形尺寸及侧壁厚度的影响规律,并得到了该拉深件最优的凹模圆角半径参数,其值比经验公式计算结果小。通过进行两个不同凹模圆角半径的对比拉深试验,验证了数值模拟结果相对于经验公式的准确性和科学性,从而为该类零件拉深工艺方案的优化提供参考。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.