巨型轴承圈锻件的锻造

随着工业生产的发展,重型机器设备愈来愈大,对各种巨型锻件的需要量也愈来愈多.巨型圈类锻件是某些重型机器设备不可缺少的零件之一.例如重型起重吊车的回转轴承,重型设备的传动大齿圈等.这些圈类锻件都是采用整体锻造或分段锻造后焊接起来的.最近我厂锻造直径将近10米的大轴承锻件就是采用后一种方法(图1),具体工艺过程介绍如下:     

基于CATIA的套环拉深级进模设计

分析了套环零件的冲压工艺,介绍了套环拉深级进模工艺计算、排样方案与结构设计。设计中充分运用CATIA参数化建模及工艺数据测取,有效缩短了设计人员工艺分析、计算时间。实践证明,模具结构可靠,产品质量稳定,对此类零件的模具设计有借鉴作用。     

300t起重吊钩的锻造成型工艺

300t起重双钩锻造过程中摒弃了忽略横向料宽比瞬时参数的常规锻造方法,采取有效工艺措施,在坯料下面加垫块,将始末料宽比限制在0.8～1.4之间,从而得到了优质的吊钩。     

连杆盖锻造模设计与制造

介绍了491Q发动机连杆盖毛坯的锻造工艺及锻造模的设计与制造加工工艺流程,阐述了模具设计的特点及要点,生产出的零件合格率高,模具成本较低,满足了企业的需求,对类似零件的锻造模设计具有一定参考作用。     

轿车的后转向节零件铸锻复合成形工艺研究

在某轿车后转向节零件试制过程中,采用了铝合金铸造锻造复合成形技术。在其工艺制定过程中,借助铸造模拟软件Adstefan和锻造模拟软件Deform,对工序中的铸造和锻造过程分别进行了计算机模拟优化。对试制的零件进行了力学性能测试和金相组织分析,结果表明铸锻复合成形工艺是一种制造轿车零件的实用而有效的工艺。     

轨梁矫直机套环的修复

攀钢轨梁厂型钢 130 0ｍｍ辊式矫直机的关键零部件套环 ,在使用过程中受磨损、挤压、间接冲击 ,内锥孔和外壁磨损而报废。其年消耗量为 32件 ,若制造新品 ,目前攀钢内部还无设备能力锻造80 0ｍｍ的锻件。因此 ,为了降成本、增效益 ,对套环的修复工作具有十分重要的作用。1　套环基本情况及修复技术指标套环材质为 34ＣｒＭｏ锻件 ,重量 1.0 90ｔ,其结构示意图见图 1。使用过程中内锥孔和外壁一般磨损 2 4ｍｍ而失效。因此 ,要求修复达到 :①恢复尺寸 ;②对表面及锥孔进行强化 ,提高其耐磨性。图 1　套环结构示意图2　修复方案为满足修复要…     

高强锻造铝合金B93

用高强锻造铝合金可制造外形复杂的零件,其中包括大型零件。这些零件实际上在所有方向上都经受相当大的载荷。这就对锻造合金提出了一系列特殊要求,锻造合金应当满足这些要求,以便得到广泛和可靠的应用。合金应具有如下性能: 1)在各个方向上,性能足够均匀; 2)可铸出直径800毫米或更大的圆铸锭; 3)良好的锻造和模锻性能,以便能够制造出机械加工最少的任何复杂零件;     

粉末锻造在国外轿车生产中的应用

叙述了粉末锻造的工艺实质、工艺流程及其要求。介绍了轿车零件粉末锻造工艺的应用实例。阐述了粉末锻造工艺的优点。     

带凸肩长方形零件的锻造工艺

带凸肩的长方形零件是机械制造中常见的零件,其毛坯多用锻造工艺生产。当零件凸肩高度增加和两肩长度加长时,将给锻造工艺带来困难。下面将一带凸肩长方形零件—安装座的生产工艺介绍如下: 对凸肩长方形锻件用自由锻造生产时,经实践证     

基于ABAQUS的径向锻造模具设计

径向锻造是加工长轴类零件及内部形状为管状类零件的常用方法之一。为了分析径向锻造中模具结构对工艺性能的影响规律,综合考虑模具设计参数,基于ABAQUS软件建立某管状类零件径向锻造三维仿真模型,对其锻造应力、应变及锻造力进行了计算。结果表明:随模具夹角减小径向锻造力增大,而应力、应变越来越小,因而变形更均匀,残余应力也更小;此外,有模芯存在时,轴对称模型与三维非对称模型锻造力及应力结果偏差较大,而无模芯存在时,二者等效应力、锻造力差异相对于有模芯存在时均较小。     

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.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

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).     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

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.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.