手工钨极氩弧焊摇摆焊操作法探析

手工钨极氩弧焊摇摆焊是一种焊缝表面及背面成形良好的焊接方法,广泛应用于多种材质板材的无障碍焊接及直径较大的管材焊接。对手工钨极氩弧焊摇摆焊操作特点及操作注意事项等进行了介绍,并与常规焊法作了对比分析,为广大手工钨极氩弧焊的实践操作者和焊接培训机构教学提供参考。     

稳压器防热冲击套管与安全端焊缝接头结构设计和焊接工艺

分别设计了适用于手工钨极氩弧焊和半自动钨极氩弧焊的防热冲击套管与安全端焊缝的接头结构形式,通过焊接试验验证了接头结构和焊接工艺的合理性.试验结果表明:采用手工钨极氩弧焊工艺方法时,焊接接头设计成带熔化嵌环的结构形式,是保证焊接接头质量的必要措施之一;采用半自动钨极氩弧焊工艺方法时,可以将焊接接头设计成带有一定钝边厚度、坡口角度适中的对接接头形式,半自动钨极氩弧焊的精确、稳定的运动轨迹,以及合适的焊接工艺参数,可以得到内外表面平整,质量优良的焊接接头.     

浅谈电站推广手工钨极氩弧焊打底焊接技术

电站中承压部件及管道焊接质量的优劣是影响发电设备安全运行的关键之一。介绍了电站焊接技术的发展现状，阐述了采用手工钨极氩弧焊打底技术的优点、金属极氩弧焊的器具及焊接工艺，在工程的应用中收到满意效果，钨极氩弧焊打底焊接技术在电站安装及检修中值得应用、推广。     

铝合金6061-T6氩弧焊焊接工艺及其性能分析

采用手工钨极氩弧焊方法对6061-T6铝合金进行焊接试验,对焊接试件、试样分别进行了外观、无损检测、拉伸、弯曲、冲击、金相检测。检测结果表明:采用手工钨极氩弧焊焊接铝合金6061-T6试件的焊接变形较大;能够达到Ⅰ级焊缝;抗拉强度较低,只能达到铝合金母材抗拉强度的60%左右;冲击韧性值远高于母材的;面弯、背弯可以弯曲至120°;焊缝接头不同区域显微组织经全面观察,未发现有微裂纹产生;液氮冷却未影响氩弧焊力学性能。     

碳素钢水平固定管的手工钨极氩弧焊打底操作技术

南京扬子乙烯工程聚乙烯装置中的所有需X射线探伤的碳素钢管均要求手工钨极氩弧焊打底,芳烃工程工艺管线的焊接大都需要用氩弧焊焊接。这里浅谈一下碳钢水平固定管的手工钨极氩弧焊打底操作技术。 1.焊前清理氩弧焊要求焊件、焊丝的清洁程度高于电     

不加衬管管形铝母线焊接技术

邯峰电厂升压站所采用的铝母线为管形，焊口不加衬管，难以采用一般的交流手工钨极氩弧焊进行焊接。采用交流方波脉冲手工钨极氩弧焊，以及平焊位置、内部充氩技术较好地解决了这一难题。本文介绍了对其进行的工艺试验，以及实际的焊接过程。     

浅论钨极氩弧焊在长输管道打底焊中的应用

在小型压力容器及承压、通球管道的焊接中，手工钨极氩弧焊电弧热量集中，电弧电压代、燃烧稳定；同时由于氩气的保护，根部焊道无渣，无飞溅，因此，常采用手工钨极氩弧焊打底，手弧焊填充，盖面的焊接方法。只要能遵守焊接工艺规程，掌握正确的操作方法，就能提高焊口的合格率，降低生产成本，提高生产时率，使氩弧焊打底在通球管线施工中得到优良的应用效果。     

不同焊接工艺对超级钢焊接接头组织性能影响

采用普通电孤焊方法(手工电弧焊、钨极氩弧焊、埋弧焊)对400MPa级超细晶粒钢进行焊接，并对不同工艺条件下的焊接接头进行了组织性能分析。结果表明，使用钨极氩弧焊方洼焊接400MP。级超细晶粒钢优于手了电弧焊和埋弧焊焊接方法。     

铝合金手工GTAW焊接缺陷及其对疲劳性能的影响

采用手工交流钨极氩弧焊、ER5356焊丝和2A12铝合金板材制备了焊接接头疲劳试样,进行了弯曲疲劳试验,并通过扫描电镜、金相显微镜等显微分析方法对焊接接头试样的疲劳断裂特征和焊接缺陷进行了综合分析.结果表明,因焊接规范不当、操作技术不熟、温度掌握不准等原因,铝合金手工钨极氩弧焊容易产生微裂纹、气孔、夹渣和未熔合等焊接缺陷,这些焊接缺陷的存在增加了焊接接头疲劳裂纹萌生和扩展速度,从而降低了焊接接头的抗疲劳断裂性能.最后分析了控制焊接缺陷产生的方法.     

化工版焊接类精品图书推荐

正焊工操作技能大全孙景荣主编☆以焊工实际操作经验为主,遵照执行国家职业标准(焊工)的操作技能要求,从手工操作的基本功入手,使焊接操作者尽快地、系统地掌握焊接操作技能。☆着重介绍了焊条电弧焊、手工钨极氩弧焊、有色金属的手工钨极氩弧焊、埋弧自动焊、二氧化碳气体保护焊、气焊与气割等常     

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.