基于电弧传感的GMAW过程焊缝缺陷识别方法

ＣＯ２气体保护焊广泛应用于自动焊及机器人及机器人焊接领域,其过程中焊接质量的自动测是目前工业界亟待解决的问题。而基于电弧传感（ｔｈｒｏｕｇｈ－ｔｈｅ－ａｒｅ ｓｅｎｓｉｎｇ）信息的监测研究,由于其特有的优势得到了越来越多的关注。本文提出一种在ＣＯ２气体保护焊过程中对焊缝摧残的自动测方法。该方法基于对电弧传感信号特征的撮通过采用自组织特征映射（ＳＯＭ）神经网络对信号分类,在焊接过程中在线识别焊缝缺陷     

IGBT逆变式波形控制CO2弧焊电源的研究

本文针对ＩＧＢＴ弧焊逆变器，提出并实现了适于短路过渡ＣＯ_２气体保护焊的输出波形控制方法。对焊接电弧参数实时采样以及工艺试验均表明，所研制的逆变式波控ＣＯ_２弧焊电源对减小金属飞溅和改善焊缝成型均有明显效果。     

CO2气体保护全自动焊“船形焊缝”在铁路米轨集箱专用平车中的应用

针对铁路米轨集箱专用平车侧梁焊接缝ＣＯ２气体保护焊焊缝质量欠佳的问题，经过多次试验，采用“船形焊缝”，选择了最佳工艺参数，并利用可靠灵敏的焊缝定位跟踪进行自动焊，获得了高质量的ＣＯ２气体保护焊角焊缝。     

CO2气体保护焊短路过渡过程的控制技术

从弧焊电源输出特性控制、焊接电流与电弧电压的波形控制、表面张力过渡控制及脉动送丝控制等几方面综述了ＣＯ２气体保护焊短路过渡过程的控制技术。在焊接电弧物理理论不断丰富和完善及现代电力电子技术、计算机技术已经发展到较高水平的今天,在减少ＣＯ２焊飞溅及改善其焊缝成形方面,电控方法有其突出的优点     

CO2气体保护焊的推广应用

ＣＯ２气体保护焊具有高效、优质、节能的特点,而其一些独特的使用特性目前尚未得到推广运用,本文通过ＣＯ２气体保护焊和焊条电弧焊工艺的比较分析,体现了ＣＯ２气体保护焊在生产中的运用价值。     

CO2气体保护焊在链轮焊接中的应用

ＣＯ２气体保护焊是一种高效、优质、低成本的焊接技术，且更易于实现自动焊，在我厂得到广泛应用，其中φ．６粗丝ＣＯ２气体保护自动焊在链轮结构中的应用就是典型一例。其焊接工艺性明显优于手工电弧焊，不但保证了焊接质量，而且还大大地提高了劳动生产率，取得了显著的社会效益和直接经济效益。     

CO2气体保护焊在链轮焊接中的应用

ＣＯ２气体保护焊是一种高效、优质、低成本的焊接技术，且更易于实现自动焊，因此在我厂得到广泛应用。其中φ１．６粗丝ＣＯ２气体保护自动焊在链轮结构中的应用就是典型一例，焊接工艺性明显优于手工电弧焊，不但保证了焊接质量，而且还大大地提高了劳动生产率，取得了显著的社会效益和直接经济效益。     

计算机控制的CO2短路过渡过程分析和检测

分析了ＣＯ２焊接的短路过程电弧特点,建立了ＣＯ２焊计算机采集及评价系统。在该系统中,实现了利用个人计算机对ＣＯ２适中过渡焊接过程的电弧电流和电压信号的高速实时采集,并对其信号进行分析,得出对焊接过程的基本估测。该系统界面友好,简单易用,可以对焊接过程的工艺及焊接电源的品质选择起一定的评估作用。     

大电流CO2自动焊在卧式容器外环缝焊上的应用

大电流ＣＯ２自动焊在卧式容器外环缝焊上的应用马洲杰（北京市中国人民解放军第三六零三工厂１０００７１）ＣＯ２气体保护自动焊是一种效率高、质量好、成本低的焊接方法。采用１．６ｍｍ焊丝，焊接电流超过３８０Ａ时，可收到明显的消除飞溅的效果，而且焊接过程稳定...     

CO2焊送丝软管绕制机的改进

ＣＯ２气体保护焊时，不管是单层送丝软管，还是双层送丝软管，都是采用弹簧钢丝绕制而成的。要绕制送丝软管，必须具备一定的绕制装备。在近二十年的ＣＯ２焊推广使用过程中，我们对绕制软管的装备进行了不断的改进，实现了既能绕制质量完全符合ＣＯ２焊接性能需要的多种送丝软管，又实现了绕制过程自动化。下面将我们改进送丝管绕制机的具体过程作一介绍，以供参考。以前，我们应用ＣＯ２气体保护焊时，由于焊机少，送丝软管使用量不大，因此绕制软管由车工在车床上完成。随着ＣＯ２气体保护焊应用的不断扩大，送丝软管数量不断增加，车床…     

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.