浅谈奥式体不锈钢的焊接质量缺陷及预防措施

奥氏体不锈钢广泛的应用在石油、化工、航空等工业中,具有良好的焊接性能,在焊接过程中也容易产生一些质量问题。本文分析了奥氏体不锈钢在焊接时焊接质量问题的原因,以及相应的缺陷预防措施。在实际焊接中只有熟悉并掌握奥氏体不锈钢焊接特点及焊接工艺,通过实践采用合理的焊接工艺措施和焊接环境,才可以焊接出完美的焊缝。     

大型箱体自动焊接装置开发及应用

该设计根据石油机械产品在焊接加工过程中所存在的技术难题，解决了手工电弧焊在生产过程中容易出现的夹渣、虚焊、挂流等焊接缺陷，达到提高工效，降低成本、保护作业人员身心健康，实现大型箱体石油机械设备的焊接自动化。通过对二氧化碳保护焊机的工作原理分析，结合设计的自动焊接小车，通过焊接小车带动自动焊接焊枪，实现对普通碳钢、合金钢的自动直线平焊缝的焊接、立焊缝的焊接，实现了焊接的自动化，同时通过调整焊接小车的运行速度与焊接电流的关系，达到系统的整体运行的稳定性，可靠性、经济性。     

CMT焊接技术在钛合金方面的应用研究

CMT(Cold Metal Transfer)冷弧焊是一种新型的熔化极气体保护电弧焊方法。该方法通过采用数字化电源和过程的精密控制技术,使得在焊接过程中可大幅度降低焊接热输入量,从而减小焊接残余应力和焊接变形。本文通过对不同厚度钛合金的CMT焊接研究,在坡口制备、焊接参数等方面确定了技术要求,成功应用于不同规格厚度的钛合金的规模化生产。     

火电厂焊接施工质量控制探讨

在火电厂安装工程中,焊接是特殊的技术工种,施工范围主要有:锅炉受热面管子焊接,水、油、气管道焊接,承重钢结构和普通钢结构焊接,还有凝汽器钛管和铝母线焊接等。本文针对火电厂油管道焊接质量的控制,通过以往工程常见问题,从焊接材料、焊接人员、焊接环境等方面进行了分析。     

隔膜贮箱电子束焊接技术研究

隔膜贮箱是一种空间系统应用较广泛的液体推进剂贮箱.在橡胶隔膜贮箱的研制中,通过对焊接过程中隔膜受热状态分析,优化选择了电子束焊接规范参数;采用了特殊焊接工艺方法,较好地控制了橡胶隔膜在焊接过程中的受热温度,通过直接测温方法测定,橡胶隔膜在焊接过程中受热的峰值温度和停留时间能够满足隔膜材料的要求.     

储罐焊接变形控制分析

本文通过对储罐焊接是一种难以施焊的工艺分析,从罐壁和罐底的焊接过程和焊接工艺方面,分析了出现焊接变形的原因对焊接的影响。同时,提出了在施焊过程中控制焊接变形应采取的措施。严格按焊评工艺参数进行施焊,从而保证储罐在焊接的过程中不变形。     

厚板7022铝合金搅拌摩擦焊接实验研究

对10mm厚度的7022铝合金进行了搅拌摩擦焊接,获得表面光滑的焊接接头,并通过X射线检测焊缝无裂纹和气孔。研究该搅拌摩擦焊接头不同区域的显微组织特征,并通过拉伸、冲击和硬度试验分析了焊接接头的力学性能。结果表明,焊缝处组织为细小均匀的等轴晶粒;在搅拌头转速为400r/min,焊接速度为100mm/min时焊接接头的抗拉强度、屈服强度均比母材高;焊接接头的冲击韧性比母材高;焊接接头显微硬度比母材稍低,焊接接头具有良好的力学性能。     

水下爆炸焊接修补实验与分析

简要叙述了爆炸焊接的发展和应用情况,总结了爆炸焊接在水下修补作业中应用的优点.通过水下爆炸焊接实验,分析了爆炸焊接的结果,验证了水下爆炸的可行性.     

基于导管钎焊热电偶控温的金属导管焊接工艺研究

通过采用导管钎焊热电偶温度控制研制了一种新的金属导管焊接方法,通过准确的温度、时间、电流的控制,达到满意的焊接质量。实现特定工艺焊接需求,操作简单,并保证导管焊接的可靠性及焊接质量。     

船舶奥氏体不锈钢管TIG自动焊腐蚀行为研究

为了研究船舶管道系统焊接件的腐蚀行为,通过全位置TIG自动焊技术对316L奥氏体不锈钢接头进行焊接,采用接头拉伸、弯曲、宏观金相测试以及通过加速腐蚀试验后腐蚀深度、表面形貌、微区电化学测试,就焊接工艺对试样的力学性能和腐蚀行为的影响进行研究。经焊接试验与检测发现,通过改变分区焊接参数设计,可有效保证焊接接头的焊接质量,焊接接头的力学性能合格。对此焊接工艺下焊接后不锈钢管道的腐蚀行为研究结果表明：焊接材料在模拟盐雾湿热/SO₂大气环境中进行腐蚀试验后以点蚀为主,腐蚀产物为团状物,且随着腐蚀过程继续进行,腐蚀产物不断生长,相互连接成片,形成完整锈层,对基材起到保护作用,延缓腐蚀向基材深入;腐蚀优先在热影响区进行,并且随腐蚀周期延长,试样母材区的耐蚀性始终高于热影响区。     

Robust sensing of arc length

During arc welding, the arc heats and melts the workpiece as heat flux. When the welding current is given, the distribution and the intensity of the heat flux are determined by the length of the are. The measurement and control of the are length are fundamental in robotic and automated welding operations. Length of welding arc determines the distribution of the arc energy and thus the heat input and width of the weld. This work aims at improving the measurement accuracy of arc length using the spectrum of are light at a particular wavelength during gas tungsten arc welding (GTAW) with argon shield. To this end, effects of welding parameters on spectral distributions were studied. To verify the effects of base metal and arc length, the arc column was also sampled horizontally as Layers for spectral analysis. Results show that spectral lines of argon atoms are determined by are length, independent of welding parameters other than the current. Based on these findings, a compact arc light sensor has been designed to measure the arc length with adequate accuracy. A closed-loop arc length control system has been developed with the proposed sensor     

Numerical and experimental studies on DC plasma spray torch

One of the challenging problems in the plasma spray technique is reproducibility of the coating quality. This problem is mainly associated with arc fluctuations, which affect the plasma jet temperature and velocity, inside the plasma torch. In this study, 3D numerical models are developed to study the arc behavior inside the torch and effect of arc fluctuations on plasma jet temperature and velocity. Plasma arc is simulated for different operating parameters. Different arc sizes are predicted by using thermo-dynamical principle of minimum entropy production for given torch power. The influence of arc current and gas flow rate on the Ar-N₂ plasma arc characteristics, plasma jet and torch efficiency is presented. Predicted torch efficiencies and arc voltages are comparable with measurements. At the nozzle exit, velocity shows stronger three-dimensional effect than temperature. Plasma jets are simulated using different nozzle exit profiles obtained from the plasma arc model and their temperature and velocity distributions are clarified.     

Failure analysis of CuW/CuCrZr contact materials in capacitor bank switch

The type test of CuW/CuCrZr arc contact used for ultra-high voltage system capacitor bank switch was conducted. Through the comparative analysis of morphologies, compositions, properties and microstructures of the contact materials before and after failure, it can be found that the abnormal open of moving arc contact and the arc erosion and mechanical wear of static arc contact are the major reasons affecting the arc contact failure. The failure mechanism and main affecting factors were investigated in detail. The results showed that arc erosion and mechanical wear are the two main factors that affect the service lifetime of arc contacts used for ultra-high voltage transmission lines and cannot be ignored. Therefore, improving the arc erosion resistance and mechanical wear resistance simultaneously is the key to prepare the arc contact materials with longer lifetime.     

粗丝CO_2气体保护焊熔滴过渡与潜弧机理的研究

本文详细分析了粗丝CO_2气体保护潜弧焊熔滴过渡的特点和潜弧机理。潜弧状态可以分为三种类型:半潜弧(熔滴主要以较大的颗粒形式过渡)、临界潜弧(熔滴主要以较小颗粒的射滴形式过渡)和深潜弧(熔滴以细小射滴与射流混和形式过渡)。大电流、低电压、粗焊丝、反极性和氧化性气氛是形成潜弧过程的必要条件,其中电流是最重要的条件。潜弧后弧柱气氛改变,焊丝端部的弧根由集中形态扩展为覆盖整个端部形态,使得熔滴尺寸变得细小,熔滴过渡形式发生变化。采用临界潜弧区域的焊接规范参数施焊,飞溅小,工艺过程稳定,焊缝成形优良。     

双弧脉冲MIG焊耦合电弧特性的数值模拟研究

针对双弧脉冲MIG焊热源稳定性差的问题,本文对双弧脉冲MIG焊耦合电弧进行瞬态数值模拟,分析了不同脉冲电流参数下耦合电弧形态、温度和压力的分布及变化规律。研究表明：耦合电弧呈驼峰状,脉冲电流发生跳变时,耦合电弧伸展或收缩,并逐渐稳定,峰值电流越小,越快达到稳定;增大脉冲电流,耦合电弧温度和电弧压力随之升高;保持总电流不变,减小主弧电流,增大旁弧电流,主弧温度和电弧压力减小,旁弧温度和电弧压力增大,当旁弧电流足够大时,耦合电弧温度和电弧压力呈双峰分布。数值模拟结果与双弧脉冲MIG焊工艺实验结果吻合良好,模拟结果对调控双弧脉冲MIG焊脉冲电流参数,改善其耦合电弧稳定性及工艺性能具有重要意义。     

电弧喷涂粉芯丝材的研究进展与应用

简述了电弧喷涂粉芯丝材的优点及制作工艺,介绍了电弧喷涂粉芯丝材的发展历程,以及耐磨损、耐腐蚀、耐高温电弧喷涂粉芯丝材的最新研究进展,展望了电弧喷涂粉芯丝材的应用前景,指出了金属陶瓷复合粉芯丝材、非晶态粉芯丝材、纳米粉芯丝材是未来电弧喷涂粉芯丝材的发展方向。     

Managing arcs in large area sputtering applications

Arc detection and power supply response technology have evolved over the years to provide significant enhancement to virtually all thin film sputtering processes. While arcing can vary in severity and process impact it is generally accepted that arcs will occur, at some level, through the course of a typical deposition. The complexity of arc detection and response has grown as thin films continue to scale becoming increasingly sensitive to the particles arcs generate. Effective optimization of arc handling requires an understanding of both the nature of, and the contributors to, arcs that are occurring. Minimizing the impact of arcs requires an appropriate response that considers their characteristics and the elements that influence or interact with these characteristics. This study evaluates many of the key factors that influence arc rate, arc energy and arc persistence in large area sputtering applications. Interactions between arc behaviors and methods used to handle them are shown to offer key insight for methods extending beyond arc handling and into what is now called arc management. Ultimately, optimized arc management offers promise for controlling the factors that affect arc formation and persistence. This, in the end, allows for more intelligent response to the arcs that occur and better control over the impact arcs have on the deposition being performed.     

超声在电弧焊接中的应用

超声场作为一种高效清洁的物理场在电弧焊接中具有越来越多的应用。在电弧焊接过程中,引入超声,可以有效改善电弧形态、熔滴过渡以及焊缝组织,最终提高焊接接头力学性能。超声在电弧焊接过程中的应用特点主要与超声施加方法有关,不同的超声施加方法具有不同的特点,根据不同的超声施加方法可将超声电弧复合焊接分为不同类型。主要综述了电弧超声技术、超声与电弧同轴复合、超声作用于焊丝以及超声工具头作用于固体母材或者焊缝表面4种技术的各自特点及研究进展,着重分析了不同技术的设备特点及其对组织与力学性能的影响。最后对该方向的研究进展进行了总结,并对其发展前景和主要发展方向进行了展望。     

等离子弧焊接铝及其复合材料研究进展

铝合金及铝基复合材料在船舶、汽车、电子电器、航空航天等许多行业中有着广阔的应用前景。而焊接技术是其广泛应用的技术关键。重点介绍了等离子弧焊技术在铝合金及铝基复合材料中的应用现状,综述了等离子弧焊接接头的微观组织性能、铝合金等离子弧焊数值模拟及新型等离子弧焊的应用,并总结了等离子弧焊接铝合金及铝基复合材料目前存在的主要问题,展望了其未来的发展趋势。     

Origin of Kern's arc

With the aid of computer-simulated halo patterns, we show that Kern's arc, as seen on the latitude of the circumzenithal arc and on the other side of the zenith, is produced by double-plate ice crystals with a vertical principal axis. Light rays that contribute to Kern's arc are demonstrated by geometric ray tracing. We also discuss the condition under which an arc that is opposite a circumhorizontal arc can appear.