焊接工艺评定适用性探讨

分析焊接工艺评定的目的和作用,结合焊接工艺评定的实际使用情况,提出什么情况下可以免做焊接工艺评定,什么情况下应做焊接工艺评定。尽量减少重复性的焊接工艺评定,并将常用钢材的焊接工艺评定形成标准,供制造和安装单位直接使用。对于新开发、新研制的钢材和焊材,必须进行焊接工艺评定,并通过试验整理出一套最佳焊接工艺用于指导生产。     

复合容器的焊接

针对容器内表面全部实施合金625的堆焊覆层技术条件要求,对于合金625的堆焊覆层,从堆焊覆层工作表面以下2 mm处的铁元素含量应不超过5%,接管法兰与筒体和管帽的部件热处理应在堆焊覆层后和不锈钢内件焊接前进行,筒体与管帽的闭合焊缝焊接和热处理存在问题,采用坡口预边堆焊隔离层,部件焊后热处理后冷态焊接闭合焊缝,图纸要求内壁堆焊层厚度和坡口隔离层厚度不小于3 mm,经焊接实验证明其复合容器堆焊覆层最小厚度应为5 mm,用焊接工艺评定验证了该结构的各项性能指标均满足标准和规范要求。     

海洋石油工程焊接工艺评定夏比冲击试验对比分析

夏比冲击试验是一种常用的评定金属材料韧性的试验方法,是焊接工艺评定过程中一项重要的破坏性试验。海洋石油工程常用的焊接工艺评定标准包括AWS D1.1、ASME B31.3、API1104、CCS《材料与焊接规范》等,主要从标准适用范围、取样要求、试样、试验温度降低值、结果评判、复验六个方面进行分析比较。归纳总结以上标准的异同点,并重点讨论试验温度降低值关键技术。     

焊接工艺评定数据库及专家系统的开发

针对工程实际需要,围绕焊接工艺评定建立了焊接性咨询系统WIS、焊接工艺评定管理数据库系统DBMS、焊接工艺规程设计及焊接接头机械性能预测专家系统ES。WIS系统通过焊接性试验数据库系统及焊接性预测系统进行各种焊接性咨询;DBMS系统不仅可以对焊接工艺评定记录进行各种方式的查询,而且可以对是否需要重新进行焊接工艺评定做出判断;ES系统一方面总结了手工电弧焊、埋弧自动焊及手工TIG焊的近200条设计规则,可以根据生产要求编制出焊接工艺规程,另一方面以大量的试验数据为基础,建立了20、20g、16MnR及19Mn6焊接接头机械性能预测模型,完全可以替代部分焊接工艺评定试验工作。     

Influence of the technological conditions of welding using the MIG/MAG method on metal transfer in the welding arc

Results of investigations on the effect of MAG welding technological conditions using filler metals and shielding gases typical for unalloyed and high-alloy steels on metal transfer phenomenon are presented. The course of investigation and the tables including ranges of parameters for specific types of metal transfer are presented for different sets of electrode wires and shielding gases. It is concluded that the test results can be used for the preparation of welding procedure specifications and welding procedure qualification records when the determination of metal transfer type is required.     

激光拼焊板焊接工艺参数的优化

为了得到最优的焊接工艺参数,提高拼焊板的成形性能,采用脉冲激光器对DC04薄板进行焊接,通过进行多组试验,对比研究了各个焊接工艺参数对焊接过程、焊缝的宏观现象及微观组织的影响,从而得到各个焊接工艺参数的可选区间.设计了1组三因素三水平的正交试验,得到了最优化的1组焊接工艺参数.试验表明,采用工艺参数为:焊接电压270V...     

转向架用SMA490BW耐候钢超射流过渡焊接工艺试验

采用超射流过渡焊接工艺模式,分别对转向架用SMA490BW钢对接接头和T型接头的底层焊道进行焊接工艺参数优化试验,并研究焊接接头的微观组织和力学性能。结果表明:在其他焊接工艺条件不变的情况下,当对接接头底层焊道的电流290 A、电压27.8 V、焊速9.4 mm/s和钝边0.5 mm时,T型接头底层焊道的电流280 A、电压27.2 V、焊速6 mm/s和坡口角度50°时,可获得较为理想的焊缝成形。与传统的脉冲MAG焊接工艺相比,超射流过渡MAG焊接工艺的熔深能力更大,焊接接头的屈服强度、抗拉强度和延伸率有所提高,符合焊接工艺评定试验标准的要求。     

焊接电源功率变换管功耗的测量

本文提出了一种实用的用于精确实时测量焊接电源功率调整管功率损耗的方法及其电路。用该电路实际测量了Ａｄａｐｔ ＭＩＧ Ｃｏｎｔｒｏｌ焊机实焊时的管耗，比较了焊丝分别为φ１．０，１．２、１．６ｍｍ时的管耗。结果表明：该种脉冲焊机的管耗并不随焊接电流的增大而线性增加，用该方法还对开关工作方式的晶体管管耗进行了研究，研究了此类电源中的主要部件，如续流管，驱动电路和滤波电路的设计以使管耗最小，这种测量方法适     

两种石油管道焊接典型标准的焊工评定区别分析

焊接海底管道常用的两个标准是API1104(2007)和DNV-OS-F101(2007)。焊工的操作技能对于石油管线的安全至关重要,焊工资质评定是控制焊接质量的重要切入点。焊工资质评定包括重要变素、焊缝检验方法、评定范围三方面的内容,结合实际工作,对比分析了两个标准在焊工资质评定方面的差异。分析表明,评定标准在焊接方法、焊接位置的表示,接头型式,填充金属材料的分类,焊缝检验方法与验收标准,母材(包括规格尺寸)评定覆盖范围等存在着显著差异。掌握标准的要求有助于提高资质评定的有效性,保证项目施工的效率和质量。     

Cooling rate effects in the welding of API 5L-X80 steel

One of the main reasons for the development of API 5L-X80 steel was its use in polar regions, where high toughness at low temperatures is required. This work studied the effect of the cooling rate in welding on the mechanical and metallurgical properties of this type of steel. Different cooling rates also simulate different welding energies. The different cooling rates were obtained with five different preheating regimes. The interpass temperature was equal to the preheating temperature of each of the double-V joints with root face, robotic welding being carried out by electric arc with shielding gas and consumable electrode (‘Metal Active Gas’ – MAG), solid wire with mechanical strength equivalent to the base metal (‘matching’) and shielding gas consisting of 75% Ar and 25% CO₂. The welded joints were analysed using light microscopy and scanning electron microscopy (SEM), as well as mechanical testing: tensile, bending, impact (Charpy-V) and hardness (Vickers). The results of the mechanical tests were satisfactory and correlated with the metallurgical analyses. The joints had high impact strength (Charpy-V) at test temperatures of up to ?40 °C.     

洛河大桥钢梁焊接工艺研究

针对洛河大桥加固钢梁所用的Q345qE钢进行焊接分析和研究,对各种焊接接头和焊接方法进行了焊接工艺评定试验,确定其预热温度和焊接工艺.各项性能试验结果表明,所用焊接材料匹配合适,焊接工艺参数合理,各项力学性能指标满足设计和相关规范要求,不但提高了焊接接头的低温冲击韧性,还有效保证了韧强比,使产品焊接接头有良好的抗脆断性...     

Problems in laser repair-welding a surface-treated tool steel

A research work is described on the development of defects in laser repair welding of a surface-treated tool steel. Repair welding tests were carried out on plasma-nitrided and on chrome-plated type 1.2738 steel plates. Welding defects in the chrome-plated samples were mainly due to chrome and oxygen overalloying of the weld metal, leading to extensive hot cracking. Cracks of the surface chrome deposit in the HAZ due to welding stresses were also detected. In the nitrided samples, welding resulted in the copious formation of gas pores due to nitrogen release during weld metal solidification. A procedure for combined laser pre-treating and laser welding of the nitrided samples was thus presented. The procedure is aimed at minimising the negative effect of the laser beam on the structural integrity of the base and welded material. The results of the microstructural analyses revealed that a significant reduction in defects could be achieved by the proposed method in the nitrided samples.     

低合金高强钢WELDOX700与WELDOX900的焊接

介绍了大型风机叶轮的焊接工艺,分析了低合金高强钢WELDOX700与WELDOX900焊接的工艺特点,针对WELDOX700与WELDOX900的焊接接头进行了焊接工艺评定试验,并对接头的微观组织形貌进行了分析,将焊接工艺参数应用于产品的组焊中,满足产品设计要求.     

关于焊接工艺评定中弯曲试验的体会

通过对焊接工艺评定中弯曲试验评定对象和目的的阐述，结合国内外的焊接工艺评定标准对弯曲试验的不同要求，对焊接接头弯曲试验的力学模型进行了数学分析，得出采用不同弯曲试验标准可以得到不同的评定结果。     

Weldability and microstructural variations in weldments of Ti-5Ta-1.8Nb alloy

The successful replacement of the present generation of corrosion-resistant materials (nitric acid-grade stainless steel and Ti) by Ti-5Ta-1.8Nb, which has better corrosion resistance, depends on its weldability characteristics. This article presents the results of a study on the fabrication, qualification, and microstructural characterization of the welds. Welding was carried out using the direct current electrode negative (DCEN) polarity tungsten inert gas (TIG) (manual) welding method with high-purity Ar shielding. Testing was carried out as per the ASME standard (section IX, welding and brazing). Qualification tests found that the weldment met the required properties. The weldment showed heterogeneous microstructures, which are rationalized based on differences in phase transformation mechanisms that are dictated by the thermal cycles experienced by various microscopic regions. The results, described in this article, confirm that the weldability of the developmental Ti-Ta-Nb alloy is excellent. A preliminary evaluation of the corrosion behavior of the welds showed rates comparable to that of the base metal, establishing that this alloy could be considered as an alternative material for use in highly corrosive environments.     

焊接接头机械性能预测专家系统——PPES

本文利用Ｔｕｒｂｏ－ＰＲＯＬＯＧ语言，建立了一个焊接接头机械性能预测专家系统，本系统不仅能够进行焊接工艺设计，而且能够预测根据设计书施焊后的焊接接头机械性能，经过试验证明，预测结果可靠，完全可以代替部分焊接工艺评定工作。     

核反应堆堆内构件焊接工艺评定

介绍了核反应堆堆内构件的主要焊缝和焊接工艺评定的一般要素,包括母材、焊材、接头型式、焊接位置和焊接方向、焊接工艺和参数以及热处理,以及使评定无效的一些关键要素。就焊接工艺评定中力学性能取样位置、弯曲试验压头直径选择、复验要求、角焊缝焊接工艺评定争议、减少焊接工艺评定数量等几方面提出了自己的见解。     

钢箱梁焊接接头的断裂韧度评定

采用冲击试验评定钢箱梁焊接工艺存在局限性,指出用裂纹尖端张开位移(CTOD)试验评定钢箱梁焊接工艺的优越性.介绍了焊接工艺CTOD断裂韧度评定的方法.针对港深西部通道香港段后海湾大桥钢箱梁焊接建造,运用英国标准BS7448对两项拟用焊接工艺进行CTOD试验评定.结果表明,埋弧自动焊工艺焊接接头的CTOD断裂韧度较高,该工艺可以直接用于钢箱梁焊接施工;而焊条电弧焊工艺焊接接头的CTOD断裂韧度较低,经扫描电子显微镜断口分析和X射线分析,发现其原因是焊缝中心存在气泡、微裂纹、夹杂物和硫等有害元素.试验评定结果为港深西部通道香港段后海湾大桥钢箱梁焊接质量控制提供了依据.     

Real time monitoring of phase transformation and strain evolution in LTT weld filler material using EDXRD

For a newly developed 10% Cr and 10% Ni low transformation temperature (LTT) weld filler material, the local phase transformation kinetics and the strain evolution during gas tungsten arc welding (GTAW) under real welding conditions was studied. An experimental set-up and a measuring and evaluation strategy are presented to gain a real time insight into the welding process. The experiments were carried out at the beam line ID15@ESRF using a two detector EDXRD (energy dispersive X-ray diffraction) set-up and high energy synchrotron X-rays. The time-resolved diffraction analysis during welding was carried out locally throughout the weld in longitudinal as well as in transverse direction to the weld line to examine the interdependence of the strain state and the transformation kinetics. This comprehension is crucial for the optimization of the weld process, and thus for the tailoring of the resulting residual stress states, which is one of the main issues for the application of LTT alloys. Using the herein proposed approach EDXRD diffraction pattern can be monitored during real welding with a counting rate of 5 Hz. By means of the time resolved diffraction data the local transformation temperatures and times were determined and the local phasespecific strain evolutions are discussed with respect to the transformation rates and the time-delayed phase transformations.     

A scientific application oriented classification for metal transfer modes in GMA welding

In this work, metal transfer in solid wire GMA welding was studied. Several experiments with different combinations of gas-wire-parameters were carried out to observe metal transfer and to characterize the various transfer modes. A laser shadograph system with synchronized electrical signals and high speed filming were used. New modes were observed and their particular characteristics described for completeness. A classification for metal transfer, oriented to scientific personnel (researchers, scholars and students), is proposed, in which the modes are independent of the type of shielding gas or welding power source.