企业是中国焊机业发展的主体

进入９０年代，中国焊机制造业发生了很大的变化，国有传统企业日益困难，新兴企业的发展也阻力重重，中国焊机制造业经历着艰苦的改变过程，但是不论怎样，进步的新生力量必将冲破各种障碍，推进中国焊机业的发展。１中国焊机业现状中国焊机制造业的发展已有４０多年的历...     

天津市焊机行业发展现状及对策研究

天津市近年来焊机行业队伍迅速扩大，非标焊接专机，逆变焊机、ＴＩＧ焊机、ＣＯ２焊机、等离子切割机，晶闸管弧焊机有阻焊控制器等焊机产品已形成了生产规模和地区特色，今后焊机行业应进一步提高产品可靠性，形成焊机产品多层次的发展结构，努力开发焊接专机，促进横向联合以使天津市的焊机行业在市场经济中健康发展。     

焊机负载持续率单片微机监控的试验研究

根据电弧焊的特点和焊机负载技术率对焊机使用的要求，研究了监控焊机负载持续率的微机系统，该系统能在焊接过程中实时发出焊机工作或休息信号，使操作人员可以按照负载持续率的要求去使用焊机，保证焊机的正确运行。     

日本CO2焊机的缺相保护

进口的日本ＫＥ系列ＣＯ２焊机具有各种保护功能，以保证焊机的可靠性。本文分析的缺相保护电路就是其中一种。使用ＣＯ２焊机的用户，其配电方式各有不同，按照ＣＯ２焊机的使用要求，在焊机的输入端应配接足够容量的空气开关或者是三相刀闸。而用户缺相的故障往往就出现在空气开关或刀闸的接线端子或焊机输入端的接线端子上。由于用户长时间的使用，造成接线端子的松动或氧化，致使电源某相接触不良甚至断路，使焊机欠压或缺相运行，造成焊接的缺陷，甚至焊机的损坏。本文分析的缺相保护电路就是为了防止缺相损坏焊机而设计的。缺相保护电…     

中国焊机行业的曙光

针对目前中国焊机行业的现状，指出中国灶机界正处在发展壮大的阶段，国外焊机制造企业进入中国的策略在发生变化；中国焊机行业是以展营企业和合资企业为主导的二分天下，而国有资本将完全退出焊机行业，中国焊机企业仍存在一些函待解决的问题。     

提高逆变焊机工作可靠性途径探讨

根据系统可靠性理论，将逆变焊机作为一个系统，探讨了提高逆变焊机靠性的途径，逆变焊机的设计决定了其可靠性的极限水平，确定了焊机的固有可靠性，焊机的加工制作只是保障实现可靠性设计的水平，加强焊机的售后服务和提高焊工的操作技能有利于维持焊机产品具有可靠性水平。     

NBC—200型CO2焊机的维护与故障排除

为了保证ＣＯ２焊机经常处于良好状态，并延长使用寿命，需要正确使用、认真保养和维护，及时排除故障。１ＮＢＣ－２００型ＣＯ２焊机的维护该焊机电路原理如下图所示。１．１焊机应按使用说明书给出的接线图正确接线；焊机的保护性接地端子必须可靠接地；焊机在接入电网...     

时代焊机的历史和现在

时代公司是中国最早从事逆变焊机开发、生产、销售的企业之一。早在1993年时代人独辟蹊径，引用IGBT功率器件和逆变技术率先在中国的焊接领域进行了一场革命。从那时开始，公司生产的全部产品均是20kHz的IGBT逆变焊机。时代公司在国内焊机行业引导并广泛推广IGBT，逆变技术的基础上，进一步将数字化技术引入焊机技术中。2003年时代公司在国内焊机领域率先采用了数字化DSP技术，占据了国内焊机技术的制高点。时代的数字化焊机现已实现批量销售，市场前景很好。     

直流焊机的焊接适应性

直流焊机由于它的使用场合决定了人们非常注意其在焊接过程中的性能，焊机特性中的外特性与动特性都是焊机焊接适应性的因素。直流焊机的焊接适应性虽与外特性有关，但在很大程度上更取决于动特性指标。本文主要分析了焊机动特性与焊接适应性之间的关系，寻找评定直流焊机焊接适应性实用的动特性指标。     

微机控制IGBT逆变焊机的研制

采用８０Ｃ５５２单片机控制半桥式ＩＧＢＴ逆变焊机，介绍了这种焊机的组成和工作原理，研究结果表明：所研制的ＺＸ７－５００ＩＧＢＴ焊机可满足手弧焊的要求，是一种节能，轻巧的大容量焊机。     

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.