手工电弧焊触电事故的预防

手工电弧焊适用范围广泛,但发生触电事故的几率较大。分析了手工电弧焊触电事故发生的直接原因和间接原因。针对这些触电原因制定了安全操作要求,包括焊机、焊钳、焊接导线的安全要求。总结了防止触电事故的安全措施,包括隔离防护、绝缘、劳动防护用品、保护接地、接零等方面。     

焊条电弧焊用电安全问题的探讨(一)--典型事故实例与分析

焊条电弧焊机多为低压电器,安全用电往往被忽视。导致在使用中存在很多安全隐患。针对这个问题,列举了数起典型的电焊机触电事故,并对事故原因进行了分析,指出焊接生产过程中的用电安全需要引起高度重视。     

焊条电弧焊用电安全问题的探讨(三)——防止触电事故的措施

大部分的焊接触电事故都是人为因素造成的,因此只要措施得当,这些事故是可以避免的.为了防止焊接触电造成的不必要死亡和严重伤害事故,不仅要通过加强焊工培训、认证、劳动保护、严格操作规程、提高人员素质等措施来规范安全管理,同时也需要采取保护性接零(接地)、交流焊机安装无载自停装置等切实可行的技术预防措施.     

焊条电弧焊补焊时焊接工艺的选择

焊接工艺的选择主要是根据被修复件的材质,补焊部位和要求,选用合适的焊接方法,制定合理的工艺(设备、材料、坡口形式、焊层、焊道、焊接顺序、焊接参数、热处理工艺等)。坡口形式要根据待补焊部位的几何形状,制定坡口的加工方法,以保证缺陷全部清除为标准;坡口形式的确定以损坏部件易于焊透,且尽量少消耗焊条为目的,另外还要考虑焊后的加工和工件的变形,还要根据工件要求进行适当清理。焊接工艺参数的选择包括焊条种类、牌号、规格、焊接电流的种类及极性,电弧电压、焊接速度、焊层、焊道及热处理工艺。①根据被焊母材的需要,选…     

焊条电弧焊操作"基础四法"

焊条电弧焊“基础四法”概括了四种不同位置试板单面焊双面成形断弧焊操作技术及运条方式,每种焊接位置的操作仅对应一字,从而达到易懂易记、印象深刻的目的。 1“基础四法”操作 (本文以板状试件为例 )　　(1)平焊位——点 　　“点”,即“两点击穿焊法”。平焊的打底焊时,焊条在坡口根部一侧位置引弧,钝边熔化后划向另一侧,待另一侧钝边熔化并形成一个整体熔池后灭弧,此为第一“点”,也是焊道的起点;当熔池未完全凝固时,在前一个熔池灭弧处,压着该熔池的 2/3重新引弧,熔化两侧钝边,观察熔孔并听到穿透的弧声,形成一个完整清…     

在焊条电弧焊焊接中克服咬边的两点窍门

咬边是焊接中较为严重的表面缺陷,会造成应力集中,严重时会引起焊缝开裂,在焊接操作中也是较难克服的缺陷,要求焊工在焊接操作中注意控制工艺参数,并注意观察熔池,保证足够的焊条摆动停留时间,对焊工技能要求较高.根据长期在焊工培训中摸索的经验,介绍两点在焊条电弧焊操作中防止咬边的窍门.     

焊条电弧焊仰焊试板的焊接

试板仰焊是省级焊工比武试件中技术要求最高、操作难度最大的竞技项目,它最能反映施焊焊工的操作技术水平.一般说来,凡能完成试板仰焊的焊工,基本上能够胜任压力容器制造或维修中各种位置的焊接,因此具有非常重要的现实意义.     

X80级管线钢焊条电弧焊焊接工艺

通过对x80级管线钢管材及焊材化学成分、力学性能的阐述,进一步剖析焊条电孤焊从根焊、热焊、填充焊到盖面焊的焊接工艺参数,为今后国内大口径X80级管线钢焊条电孤焊焊接施工提供了详实的数据。     

从对标准的质疑谈复合钢焊条电弧焊的工艺要点

复合钢的焊接包括异种钢和同材质钢的焊接，而又具有其本身的焊接特性，因而对复合钢焊接工艺必须认真对待。设计合理的接头形式；正确选用焊接材料、按照合格的焊接工艺评定确定焊接工艺参数；并按合理的焊接顺序进行焊接操作可以较好地保证焊缝质量，形成高质量的焊接接头，对不合格焊缝的返修，其工艺因复合钢的特殊性有与一般焊接焊缝返修不同的要求，负责复合钢焊接的技术人员一定要慎重，同时注意不同阶段无损检测的完整性和严密性。     

水下焊条电弧焊扩散氢含量及焊缝组织特征分析

对影响水下焊条电弧焊扩散氢含量的主要因素和焊缝组织进行分析研究.结果表明,电弧周围的水对焊缝增氢的贡献并不大,仅仅使扩散氢含量增加0.4%,扩散氢来源的主体是药皮中的结晶水和防水层材料所携带的H元素,分别使扩散氢含量增加12.1%和21.8%,工件表面的铁锈也是焊缝增氢的一个不容忽视的因素,会使扩散氢含量上升达28.2%.焊缝组织为少量的侧板条铁素体和贝氏体,热影响区(HAZ)则含有大量马氏体组织.其焊接接头的最高硬度一般都超过0.4 GPa,硬度峰值出现在熔合线附近,在焊缝热影响区内会形成典型的焊道下裂纹缺陷.     

Weldability and toughness evaluation of pressure vessel quality steel using the shielded metal arc welding (SMAW) process

The present study was carried out to assess the weldability properties of ASTM A 537 Cl. 1 pressure-vessel quality steel using the shielded metal arc welding (SMAW) process. Implant and elastic restraint cracking (ERC) tests were conducted under different welding conditions to determine the cold cracking susceptibility of the steel. The static fatigue limit values determined for the implant test indicate adequate resistance to cold cracking even with unbaked electrodes. The ERC test, however, established the necessity to rebake the electrodes before use. Lamellar tearing tests carried out using full-thickness plates under three welding conditions showed no incidence of lamellar tearing upon visual examination, ultrasonic inspection, and four-section macroexamination. Lamellar tearing tests were repeated using machined plates, such that the central segregated band located at the midthickness of the plate corresponded to the heat-affected zone (HAZ) of the weld. Only in one (no rebake, heat input: 14.2 kj cm^-1, weld restraint load: 42 kg mm^-2) of the eight samples tested was lamellar tearing observed. This was probably accentuated due to the combined effects of the presence of localized pockets of a hard phase (bainite) and a high hydrogen level (unbaked electrodes) in the weld joint. Optimal welding conditions were formulated based on the above tests. The weld joint was subjected to extensive tests and found to exhibit excellent strength (tensile strength: 56.8 kg mm^-2, or 557 MPa), and low temperature impact toughness (7.4 and 4.5 kg-m at-20 °C for weld metal, WM, and HAZ) properties. Crack tip opening displacement tests carried out for the WM and HAZ resulted in δ_m values 0.36 and 0.27 mm, respectively, which indicates adequate resistance to brittle fracture.     

新型的气体保护熔化极电弧冷焊工艺

应用高效的气体保护熔化极电弧焊焊接铝合金薄板时,容易出现熔池下塌、烧穿等焊接缺陷.新型的气体保护熔化极电弧冷焊工艺通过控制负极性比率能够降低电弧输入熔池的热量,从而在保持高效焊接的基础上稳定焊接质量.介绍了新型的气体保护熔化极电弧冷焊工艺控制焊缝成形的效果,阐述了这种新型冷焊工艺的两种控制模式及电弧运动过程.     

应用光谱技术进行熔化极气体保护焊熔滴过渡的研究

熔滴过渡的研究对于焊接控制具有重要意义,本文综合评价了现有熔滴过渡的检测方法,指出了其存在的各种不足。依照信息学的观点并借鉴频谱分析的思路。提出了应用光谱技术研究熔滴过渡的设想。在此基础上,简介了光谱检测的原理,测试表现光谱信号在反映熔滴过渡上具有优良的信号品质,富含多方位的信息。此研究结果将会拓展焊接质量控制的领域,丰富焊接电弧物理的知识内容。     

Boride coatings on steel using shielded metal arc welding electrode: Microstructure and hardness

In the present study, shielded metal arc welding electrodes were produced for making boride coatings and low-carbon steel plates were surfaced with single-pass bead on-plate welds. The effects of the boron content in the electrode shield on the microstructure and hardness of the coatings were investigated. After deposition, microstructural analyses including metallographic examination, wavelength-dispersive X-ray (WDX), X-ray and microhardness measurements of the coatings were evaluated. From the results, it was seen that different boron contents formed primary and eutectic Fe₂B, and consequently had an effect on the hardness of the coating. As the amount of boron which was transferred from the electrode shield to the coating increased, the microstructure of the coating changed from the eutectic structure (α-Fe + F₂B) to primary Fe₂B with the eutectic of Fe₂B plus martensite, and the hardness increased. The present study has therefore shown that the shielded metal arc welding electrodes produced here for the first time can be used effectively and economically to produce boride coatings on SAE 1020 steel.     

Coating composition,weld parameter and consumable conditioning effects on weld metal composition in shielded metal arc welding

Abstract

Pipeline construction has been moving towards the use of higher strength low carbon steels as these become available. In order to achieve the required high strength and toughness to match those of the parent pipe, girth weld metals have to rely mostly on their composition. The aim of the present study was to characterise the influence of the consumable chemistry and moisture content, and the welding parameters on the composition of weld metals produced by E8010 and E9010 shielded metal arc (SMA) cellulosic consumables. The alloying compounds in the consumable coating were isolated using a caustic soda solution, analysed with electron backscattered diffraction and identified as a variety of oxides. Making use of a mechanised SMA welding machine, the effect on weld metal alloying element contents of the welding conditions was evaluated. Smaller welding arc voltages and lower consumable coating moisture content produced weld metals with richer chemistry. The element transfer mechanisms from the consumable coating to the weld metal are also discussed.     

气体保护焊实心焊丝在金属结构行业中的应用与探讨

简要概述了国内外气体保护焊实心焊丝的发展情况,介绍了气体保护焊实心焊丝在金属结构行业的推广应用状况,根据试验结果与生产实际,对国内实心焊丝在推广应用中存在的问题进行了探讨,最后阐述了国内气体保护焊实心焊丝的发展趋势.     

基于RCD和保护接地的电弧焊防电击策略

讨论了应用RCD防范焊接电击的基本原理,并提出了RCD主要技术参数的选用要点;讨论了应用保护接地技术防范焊接电击的原理和方法;对RCD与保护接地的保护特性进行比较,着重分析了这两种保护方法各自的优点和缺陷;介绍了RCD与保护接地技术用于防范焊接电击的接线示例;强调了装设电焊机空载自动断电保护装置的必要性和优越性.     

气体保护焊烟尘形成机理分析

以H08Mn2Si实芯焊丝的熔化极气体保护焊和SJ501药芯焊丝的CO₂保护焊为对象,探讨了气体保护焊烟尘粒子的粒径分布特征和形成机理. 采用准光弹性散射法测量烟尘粒径,并利用透射电镜(TEM)、能谱(EDS)对烟尘粒子的形貌、结构和化学成分进行了观察和分析. 结果表明,两种工艺形成的烟尘一次粒子都呈球形,表面圆滑,直径一般小于200 nm,大多数烟尘粒子都是铁的氧化物. 研究还发现,烟尘的二次粒子为链状或网状结构,由大量一次粒子聚结而成,与实芯焊丝的熔化极气体保护焊形成的烟尘相比,药芯焊丝CO₂焊形成的烟尘化学成分更复杂,烟尘二次粒子更细小.