基于RSM与NSGA-Ⅱ的法兰件挤压成形工艺的多目标优化

通过分析实心法兰的结构特点，运用有限元模拟与响应曲面算法和NSGA-Ⅱ相结合的算法对实心法兰冷挤压成形进行了多目标优化分析。采用DEFORM-3D有限元模拟软件对实心法兰成形过程中的损伤与载荷进行了分析。选取摩擦因数、凹模圆角半径和挤压速度3个工艺参数为影响因素，损伤值与载荷力为优化目标，通过设计响应曲面试验进行仿真模拟。结合NSGA-Ⅱ遗传算法进行多目标优化，对优化解进行仿真试验对比，目标值误差位于合理范围内。工艺参数优化的最终结果为：挤压速度1.46 mm·s^-1、摩擦因数0.05、凹模圆角半径8.00 mm,采用优化后的参数进行模拟试验，结果表明，法兰的最大成形载荷由100 kN降低为50.9 kN,损伤值由1.29减小至0.70,工件的成形质量得到改善。     

磁控排气管挤压成形的分析与参数优化

根据挤压成形理论,分析、制定了磁控排气管挤压成形工艺,采用Deform-3D软件对零件的成形过程进行模拟,应用正交模拟试验和回归试验以及工程试验研究相结合的方法,对微波炉磁控排气管金属冷挤压成形规律进行了研究,对工艺参数进行了优化.确定了模具结构参数的优化组合为:凸模内圆角r1=0.8 mm,凸模外圆角r2=0.8mm,凹模内圆角r3=0.2 mm,凹模外圆角r4=0.8mm.工艺参数的优化方案为:坯料直管长度x1=30nm,坯料锥角x2=120°,摩擦因子x3=0.1,挤压速度x4=180 mm·s-1.实现了薄壁空心杯杆件的复合挤压成形.     

车用法兰连接件冷成形工艺研究及优化

首先,以某车用法兰连接件为研究对象,根据其结构提出了一种拉深、冲孔、翻边、冷镦挤的多工位成形工艺,采用有限元软件Deform-3D对冷镦挤工位进行了模拟分析,并设计了3种不同结构坯料的方案,基于数值模拟结果,获得了最佳成形方案,即采用锥形坯料;其次,为获得冷镦挤的最优工艺参数,以上冲头、固定块以及凹模承受载荷的最小值为优化目标,建立了关于凹模圆角半径、摩擦因数、镦挤速度、固定块圆角半径的4因素3水平正交试验表,并结合有限元分析了各试验因素的关键程度,采用极差分析获得了法兰连接件的最优镦挤工艺参数组合,即凹模圆角半径为8 mm、摩擦因数为0.1、镦挤速度为30 mm·s^-1、固定块圆角半径为6 mm;最后,通过实际试生产,获得了符合要求的法兰连接件,验证了方案的可行性。     

异形齿离合器盘毂冷挤压工艺优化分析与实验研究

针对某带有异形齿法兰离合器盘毂的结构特点提出冷挤压成形工艺。结合有限元分析与正交试验设计方法,以异形齿盘毂冷挤压成形峰值载荷、齿形充填情况以及最大损伤值为目标函数进行正交实验设计,并采用有限元模拟软件分析其凹模入模半锥角、凹模过渡圆角半径、坯料直径、摩擦系数和挤压速度对盘毂冷挤压成形性的影响。分析结果表明:凹模入模半锥角、凹模过渡圆角半径、坯料直径对盘毂冷挤压成形性具有显著影响,并得到最佳工艺参数组合为:入模半锥角40°、凹模过渡圆角半径3 mm和坯料直径Φ53.5 mm。工艺试验结果表明,采用优化后的盘毂冷挤压工艺可以生产出质量合格的产品。     

小规格TiNiNb管材的反向挤压成形工艺参数

针对44 mm×10.5 mm小规格Ti Ni Nb管材反挤压成形试验的工艺参数确定和模具设计问题,采用有限元热力耦合数值模拟和单因素轮换法,分析在满足制件成形质量(挤出温度低于共晶熔点)的前提下,挤压力与凹模模角和定径带长度、凹模和挤压筒温度、毛坯初始温度、挤压速度及摩擦因子等工艺参数和模具结构参数之间的关系,确定影响挤压力的主要工艺参数和模具结构参数分别为凹模模角、初始坯料温度、挤压速度和摩擦因子,并给出上述参数的取值范围。通过基于数值模拟的正交试验方法,得到了主要工艺参数和模具结构参数的最佳组合,即在保证润滑效果的前提下,取凹模模角110°、毛坯初始温度为950℃、挤压速度为50 mm/s。利用铅和45号钢毛坯在6.5 MN多向模锻挤压液压机上进行了验证实验。     

工艺参数对铝合金屏蔽罩冲压特性的影响

针对盒形冲压件成形过程中易出现破裂、起皱和回弹过大的问题,采用有限元分析软件DYNAFORM对顶部弧面、侧壁直边的磁体外盖进行拉延、切边和回弹过程模拟,分析制件成形规律;采用正交实验法模拟研究压边力、凹模圆角半径、模具间隙和冲压速度等工艺参数对制件冲压成形的影响。以制件的最大减薄率和回弹量为评价指标,采用极差和方差分析法对模拟结果进行分析表明,各工艺参数对评价指标的影响显著性,得到的最佳工艺参数优化组合为压边力120kN、凹模圆角半径3mm、模具间隙1.05t、冲压速度6m·s-1。采用优化工艺参数组合进行模拟和冲压实验,获得了较好的评价指标值,实验结果与模拟结果相吻合。     

基于数值模拟的大长径比筒形件正挤压成形工艺研究

基于DEFORM-3D数值模拟软件,以某深孔汽缸为研究对象,建立了大长径比筒形件正挤压成形的有限元仿真模型,研究入模角α、凹模圆角r、定径带长度h、挤压速度v等工艺参数对金属塑性变形的影响;以挤压力峰值Lmax、坯料损伤峰值Dmax和凹模磨损量W为优化目标,进行正交试验方案设计,分析各工艺参数对优化目标的影响规律,获得较合理的工艺参数组合。研究结果表明,当入模角α=90°、凹模圆角r=3 mm、定径带长度h=20 mm、挤压速度v=10 mm/s时,可有效降低挤压力峰值和凹模磨损量,保证了零件的成形质量与模具的使用寿命。     

基于正交试验的离合器波形片冲压成形工艺参数优化

基于DYNAFORM有限元软件的数值模拟,利用正交试验研究了凸、凹模间隙,冲压速度,弯曲半径以及板料厚度4种工艺参数对波形片成形高度的影响。通过正交试验的直观分析得出各因素对波形片成形高度影响的主次顺序依次为:凸、凹模间隙,弯曲半径,板料厚度,冲压速度。此外,由正交试验得出波形片成形的最优试验方案为:凸、凹模间隙为1.0t,冲压速度为5000 mm·s-1,弯曲半径为24.3 mm以及板料厚度为0.8 mm。波形片优化后的试验方案模拟值与试验值分别为2.94和2.62 mm,两者的误差为12.21%。     

基于BP神经网络的镁合金轮毂旋转挤压工艺

以镁合金轮毂挤压成形工艺为研究对象,采用有限元分析软件DEFORM-3D对其成形工艺进行模拟。为使制件成形效果达到最佳,选取凸模冲压速度、凹模旋转速度、成形温度作为输入层,以成形后制件的损伤值和应变标准差为输出层,通过构建关于工艺参数的BP神级网络对输入、输出层参数关系进行拟合。并采用遗传算法,基于构建的神经网络寻求最优解。得出最优参数组合为:凸模冲压速度为5. 0 mm·s~(-1)、凹模旋转速度为30 r·min~(-1)、成形温度为380℃,采用最优参数进行试模,制件成形效果良好,与预测结果基本一致,验证了有限元模拟和优化的正确性,为实际生产提供指导。     

AZ80镁合金锥形件内环筋挤压成形工艺参数研究

镁合金锥形件内环筋通过旋压无法形成高筋。因此,提出斜楔加载整体成形工艺。通过DEFORM-3D软件模拟了AZ80镁合金锥形件内环筋成形过程,采用正交试验法分析了反挤成形过程中挤压温度、挤压速度、分瓣凸模圆角半径对成形过程中最大载荷和平均应变的影响,并对金属流动和等效应变规律进行了分析。结果表明:AZ80镁合金锥形件内环筋的最佳成形温度为410℃,最佳挤压速度为2 mm/s,最佳分瓣凸模圆角半径为55 mm。通过实验,环筋部位填充饱满,零件达到使用要求。     

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.