汽车焊装车间烟尘的治理与除尘系统优化

分析汽车焊装车间烟尘的组成及特性,阐述基于整体除尘混合送风和分层送风方式下气流特点和除尘原理.从除尘原理出发,优化设计送风口的形式和送风位置,并对比分析除尘效果,分层送风置换通风除尘效果明显,能有效降低工作场所烟尘浓度,为从业者的健康安全提供保障.     

高速列车焊接作业厂房环境治理技术

介绍高速列车焊接作业厂房焊接污染物的治理难点,焊接污染物成分、粒径分布和危害;分析整体厂房分层送风的原理及优势。通过整体厂房分层送风在高速列车焊接作业厂房的成功应用,得出结论:整体厂房分层送风能够为焊接作业厂房提供一个良好的热舒适性环境,并能提高车间内的空气品质。     

药芯焊丝在压力容器焊接中的应用试验

对焊机改装、焊接工艺评定试验、压力容器焊接试生产等方面进行了介绍,提出了保证药芯焊丝送进通畅、防止将药芯焊丝压偏的方法;采用加中药的送风装置吹风,减少在容器内进行药芯焊丝半自动的烟尘污染,总结了药芯焊丝在我厂压力容器制造中的试用经验及防止焊接缺陷产生的措施。     

安全技术、劳动保护和环境保护：焊接电参数对钛型渣系FCAW烟尘产生的影响

为了研究焊接电参数对钛型渣系FCAW烟尘产生的影响，采用光散射法和光纤型准光弹性散射颗粒粒度测试仪测量钛型渣系FCAW烟尘的粒度，根据JIS标准，在不同的取样条件和焊接工艺参数下进行烟尘发尘量测量试验，探索了普通钛型渣系FCAW烟尘的粒度分布规律，分析了焊接工艺参数对烟尘发尘量的影响，并研究降低烟尘发尘量的措施。研究结果表明，     

术语之窗

焊接烟尘weldfume焊接时，由焊接材料、母材及其冶金反应产物等的蒸发和氧化产生的在空气中浮游的烟雾状微粒。一般常含有各种金属的氧化物和氟化物。焊接发尘量totalamountoffumes焊接时，单位质量的焊接材料（如焊条、焊丝等）所产生的烟尘量，单位为mg／g或g／kg。焊接烟尘浓度weldfumeconcentration焊工工作地点单位体积的空气中所含焊接烟尘的量，单位为mg／m３。焊接烟尘容限浓度thresholdlimitvaluesofweldfume（TLV）焊接烟尘在空气中的允许浓度。在这一浓度下进行焊接作业，对焊工不引起危害健康的作用。焊接发尘速率weldfumeemi…     

焊接材料对形成焊接烟尘影响的研究进展

为减少焊接烟尘对人体的危害,必须考虑降低焊接时的发尘率,并减少烟尘中有毒成分的含量和危害性,而焊接材料正是影响焊接发尘率和烟尘成分的关键因素。针对GMAW焊接材料对焊接烟尘形成的影响,分别综述了焊丝和保护气体成分对焊接发尘率的影响、焊接烟尘微观形貌特征和成分以及焊接烟尘的形成过程,并进一步阐述了基于数值模拟的焊接烟尘形成机理的分析方法。     

药芯焊丝焊接烟尘的产生机理研究

药芯焊丝在焊接过程中产生大量烟尘,对环境和操作人员健康造成巨大影响,了解焊接烟尘的形成机理对其监控具有重要意义。采用高速摄像方法及背光拍摄技术,对高速变化的药芯焊丝焊接电弧及烟尘形态进行拍摄,分析焊接过程中烟尘产生的机理。结果表明:药芯焊丝焊接烟尘主要在焊接电弧外侧区、飞溅烟尘区、熔滴烟尘区三个区域产生。在电弧区产生均匀分布的烟尘,是焊接烟尘的主体。在飞溅烟尘区、熔滴烟尘区产生聚集性烟尘,会大大增加烟尘总量。在此基础上给出了烟尘产生和扩散的物理模型,探究了焊接烟尘的产生机理。     

高效低尘结构钢焊条及焊接烟尘影响因素研究

采用正交设计研制出一种低烟尘结构钢焊条，并对焊条的主要药皮物质（铁粉、还原钛铁矿和天然金红石）进行试验分析，得出几种焊条药皮物质对于焊接烟尘量的影响规律。同时陈述了焊接工艺参数对焊接烟尘的影响规律，最后对该焊条的焊接工艺性及焊接接头的力学性能进行了验证。     

焊接操作中的危害因素及防护

简要介绍了焊接操作中电气、光辐射和噪声等带来的危害和影响。着重分析了焊接烟尘对焊工可能造成的危害及预防措施，并指出无论是焊接工程技术人员还是焊接工人都要加强对焊接烟尘危害的认识与重视。     

焊接烟尘的危害及综合治理研究现状

焊接作为一种基础工艺,广泛应用于工业制造的各个领域。焊接及其作业过程中产生的弧光、电磁辐射、有毒气体及烟尘颗粒不仅污染环境,也对从业人员的身体健康造成了极大的危害。焊接烟尘是焊接生产中对健康环境影响最为复杂且治理难度最大的伴生危害,因此开展焊接烟尘治理的研究对改善焊接生产环境及保护从业人员身体健康具有重大意义。本文综述了焊接烟尘的形成机理、危害及治理措施,分析了在工程应用中焊接烟尘治理存在的问题,指出了焊接烟尘治理的发展方向。     

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).     

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.     

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.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。