电弧焊热输入的确定和测量

介绍了新的热输入(电弧能量)计算方法,应用背景及如何确定和测量计算公式中的各个参数,包括传统方法中的焊接电流、电弧电压、焊道长度及新计算方法中的电弧能量、功率。相对于传统方法,新的计算方法在生产中具有广泛的认可范围,可以节省大量成本,针对新的设备(特别是新型有波形控制的设备)可以减少重复的焊接工艺评定和焊接工艺验证的工作。     

电子枪设计的小会聚角原理

深穿透电子束焊接及电子束热处理,对电子枪设计提出了某些新问题。本文在电子光学分析和实验研究的基础上,提出了电子枪设计所依据的小会聚角原理,介绍了应用这一原理设计电子枪的基本方法及实例,给出了这种电子枪的实验结果。用这一原理设计的电子枪,具有比按原有方法设计的电子枪有更强的电子来穿透能力,更适于深穿透焊接,也更适于低电压下精密焊接及热处理等应用。     

通用小型脱箱造型机(FBS型)

目前在工业上提倡节省资源、节省能源、轻薄短小。作为其代表例可以举出;在汽车工业中追求轻量化、小型化、低燃料消耗化。这种倾向在铸造界也不例外,今后这种倾向还会加速。基于这样的时代背景,对铸造设备提出了种种要求,如果按其内容分类,可以归纳成以下形式: (1)提高产品的性能(轻量化、节省资源     

新型微合金化460 MPa级汽车大梁钢

为满足汽车市场的技术要求,需要开发的新型高强钢除了要具有较高强度外,还应具有较高的强韧性、冷成形性能、较好的应变分布和较高的应变硬化指数、高的强塑积、良好的烘烤硬化特性及耐疲劳性能等,而且横向、纵向、45°方向各项异性小。使用新型高强钢不仅能够减轻汽车自重,还可以提高汽车安全系数,节省汽油消耗,提高载重量,减少尾气污染等。文章针对新型高强钢的成分设计和控轧控冷工艺进行了分析,开展了屈服强度460 MPa级汽车大梁钢的研发工作。通过调整组织、力学性能及韧性等,确定该产品最佳的化学成分和热连轧工艺参数,为研制高等级的汽车大梁钢积累了宝贵经验。     

液压技术在混合动力汽车节能方面的应用

介绍了一种采用液压混合动力的新型环保节能车辆,它利用液压元件功率密度大的优点,构造了以液压蓄能器和双向可逆液压泵为核心的刹车能量再生系统,这种系统与发动机动力源一起可以组合成3种不同的驱动形式,从而实现具有两个动力能源的混合动力车辆.这种车辆在降低油耗、减少排放污染、提高刹车装置使用寿命等方面具有较大的优势,特别适合于行驶在有频繁起停的城市交通或山地城市交通路况.     

新型碳化硅晶体管

美国Semisouth实验室得到美国导弹防御局的资金的支持已经开发出尺寸、重量和生产成本均降低的新型碳化硅晶体管,将取代现有的晶体管。据有关资料报道,SIC晶体管的能量是硅基晶体管能量的10~100倍,其值高达3GH2,甚至可以达到10GH2,当按电压增益、功率增益和开关量损失来检测时,新型晶体管的性能增加25%~30%。过去传统的SI晶体管生产工艺为13段,而现在SIC晶体管生产工艺为6段,因此新的生产工艺可以使晶体管质量翻一番,成本节省超过60%。新型SIC晶体管生产工艺极具竞争力,新型SIC晶体管市场潜力巨大。新型碳化硅晶体管…     

大功率电子枪的新型LaB6阴极

轰击式LaB6阴极是一种电子枪的新型阴极,它不仅具有良好的电子光学系统结构,而且电子发射能力强大,对大功率电子枪的研制和开发具有重要意义。论述了新型轰击式LaB6阴极的工作原理、研究的意义、阴极材料的选择,并完成了轰击式阴极的设计和计算,设计完成了轰击式LaB6阴极的试验装置。通过试验得到,该轰击式LaB6阴极在阴极温度为1843K时具有最大发射电流450mA,其发射电流密度为3．58A／cm^2。列举了典型试验数据并进行分析,得到所选用的LaB6的发射常数A为21．33,逸出功Фs为2．6eV,这与理论值非常接近,证明了试验的准确性和可靠性,该试验结果为大功率电子枪的研究开发、为大功率电子束焊接设备的研制奠定了基础。     

新型三辊定心装置的研制与应用

江西洪都钢厂研制的穿孔新型定心装置结构紧凑，定心准确可靠，对提高穿孔毛管质量效果明显。该装置还具有辊子磨损后调整方便，运行平稳，零部件不易损坏，节省维修费用，降低能耗等诸多特点。     

一种具有吸震及导向功能的限位螺栓

介绍了一种新型的螺栓结构,这种螺栓结构同时具备吸震、导向和限位功能。该新型螺栓用于汽车覆盖件冲压模具中压料芯的限位和导向,当压料芯回程时,压料芯会对限位螺栓产生冲击力导致受力不稳,而使用新型限位螺栓在保证自身受力平稳的同时还具有缓冲效果,而且新型限位螺栓自身具有导向功能,可以保证安全生产,从而提高了生产效率。     

电子枪钉子高效自动复合精密冲压成形及模具设计

设计了一种高效自动复合精密冲压成形模，利用普通压力机在同一冲压行程内从三维方向自动完成电子枪Ｇ２钉子冲压的下料（切断）、压扁、弯曲、成形等四道工序的精密成形，并自动完成卸料动作。这种成形方法完全可以替代目前普遍采用的进口的电子枪钉子制造专用机器成形方法，且其生产效率高于后者。本成形方法采用的模具结构设计精巧，成形质量可靠，既适应于自动送料情形，同时可以采用手动送料。这种模具结构亦成功地应用于Ｇ３钉     

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.