压力钢管的焊接工艺规程WPS

黄河小浪底压力钢管属超大型压力钢管，采用美国ASME标准的高强调质钢，A517和高强正火钢A537钢板。此工程由外商总承包，并严格按美国ASME标准检查和验收。为确保焊接质量，编制了焊接工艺规程WPS，并按此规程针对不同板厚、不同接头形式、不同焊接方法分别作了工艺评定试验，其结果均符合小浪底压力钢管技术规范要求，符合美国ASTM标准和外商的评定要求。     

ASTM A335 P5耐热钢管线返修焊接工艺开发

文中介绍了ASTM A335 P5耐热钢管线的性能特点,对该耐热钢进行了焊接性分析。通过焊接工艺评定,研发了耐热钢的氩弧焊返修焊接工艺。采用适宜的焊接工艺参数和技术措施,严格控制预热温度、道间温度、热输入、消氢处理和焊后热处理,得到合格的返修焊接接头,试验结果满足项目和规格书的要求。     

2A97铝锂合金激光焊接特性

对厚度为2.0 mm的2A97铝锂合金进行了无填丝的激光焊接试验.通过拉伸试验、显微硬度计、光学显微镜以及扫描电镜研究了不同焊接热输入(激光功率、焊接速度)下焊接接头组织和性能.结果表明,随焊接热输入的增加,焊接接头系数增大,该厚度下2A97薄板最佳的焊接热输入为0.9~0.95 kJ/cm,此时接头系数可达到0.8左右.焊缝中的柱状晶分布区是强度最低区域,随焊接热输入的降低,焊缝区域中粗大的柱状晶所占比例增大,同时有伴随大量气孔出现,导致接头系数降低.     

热输入对921A钢焊接接头性能及显微组织的影响

以10 kJ/cm、15 kJ/cm、20 kJ/cm三种不同焊接热输入焊接921A低合金高强钢,研究焊接热输入对焊接接头组织及力学性能的影响。研究结果表明,随着焊接热输入的增大,焊缝中晶粒尺寸增大,针状铁素体增多;热影响区晶粒长大的趋势亦随着热输入变化明显;热影响区粗晶区在焊接热循环的作用下变化明显,其组织均由板条马氏体和贝氏体组成。在不同热输入条件下焊接热影响区出现软化现象,且随着焊接热输入的增加,焊接热影响区软化问题越突出。通过拉伸试验表明焊接热输入在10~20 kJ/cm条件下,焊接接头获得了较高的强度。     

超强调质钢巨型压力钢管的焊制

黄河小浪底水利枢纽工程引水压力钢管属超大型压力钢管，采用美国ASTM标准A517钢板焊制。压力钢管因尺寸超大、刚度强，预热装配和焊接过程中出现焊缝张开及缺陷严重超标的现象。经多次试验摸索后．解决了这些难题。本文详细叙述了巨型压力钢管的预热装配和焊接过程。     

A7N01P-T4铝合金MIG焊焊接工艺的研究

通过拉伸、弯曲和硬度等试验以及显微组织分析,对不同焊接热输入和不同预热温度下A7N01P-T4铝合金焊接接头的组织与性能进行了研究。结果表明:当焊接热输入增加和预热温度降低时,接头的抗拉强度有所提高,所有试样均在焊缝处断裂且接头的抗拉强度均满足相关标准要求。除小焊接热输入以外的不同焊接热输入和不同预热温度下的焊接接头均具有良好的弯曲性能。焊缝处硬度最低,接头均无软化现象。接头各区域的显微组织也没有明显变化。     

高强度调质钢A514的焊接工艺

详细分析了A514钢的焊接存在冷裂倾向和热影响区性能的脆化和软化问题,通过选择低氢型焊接材料,小热输入的焊接方法,辅以合理的预热温度以及焊后不需热处理的工艺设计,并经过焊接工艺评定试验,确定了本公司采用焊条电弧焊、药芯焊丝气体保护焊、实心焊丝气体保护焊的焊接工艺参数,同时满足AWS D1.1和CCS的焊接要求。     

超强调质钢巨型压力钢管的焊制

黄河小浪底水利枢纽工程引水压力钢管属超大型压力钢管,采用美国ASTM标准A517钢板焊制。压力钢管因尺寸超大、刚度强,预热装配和焊接过程中出现焊缝张开及缺陷严重超标的现象。经多次试验摸索后,解决了这些难题。本文详细叙述了巨型压力钢管的预热装配和焊接过程。     

热输入对B610CF钢焊接接头性能的影响

采用混合气体保护焊和焊条电弧焊2种焊接方法,对低碳贝氏体B610CF钢在不同热输入下进行焊接,研究不同热输入对B610CF钢焊接接头性能的影响。冲击韧性试验研究和微观金相组织分析表明,不同热输入对焊缝区显微组织影响明显,随着热输入的增大,焊缝区贝氏体含量下降、晶粒变得较粗大,焊缝冲击韧性明显下降;但热影响区组织没有明显差异,且冲击韧性也没有明显差异。拉伸试验、弯曲试验结果表明,不同热输入对焊接接头的强度和的影响不明显。为了提高焊接接头的性能,不宜采用过大的热输入。     

X65M管道自动焊接头微观形貌与力学性能研究

采用不同焊接工艺参数对X65M D559 mm×12.7 mm钢管进行全自动焊，焊接完成后对环焊缝进行外观检测、射线检测、微观形貌分析与力学性能研究。结果表明：2种焊接工艺参数下获得的环焊缝外观成形良好，射线检测满足相关标准要求，焊缝拉伸试验、面弯试验、背弯试验、-20℃冲击试验、系列温度冲击试验等性能较好。但在小热输入工艺条件下，焊缝不同位置微观形貌产生不同程度的侧壁未熔合缺陷，焊缝刻槽锤断试验也出现明显的未熔合缺陷。     

Novel method of thermite welding

Abstract

This article presents a novel method of thermite welding. A hand operated portable welding can be conveniently realised using self-made thermite welding pencil without any welding equipments. A butt junction was obtained between two low carbon steel plates. Morphological, microstructure and mechanical analyses of the weld bead were carried out. The results demonstrated that the two steel plates were jointed by fusion bonding with the filler. No defects such as porosity and microcrack were found. The hardness test showed the low hardness of the fusion zone compared with the base material. In addition, the grain growth in HAZ did not affect the hardness of the base material. The average tensile strength of welds was 285·4 MPa, ～70% of the average tensile strength of low carbon steel.     

Analysis of process parameters effects on dissimilar friction stir welding of AA1100 and A441 AISI steel

Abstract

A prominent benefit of friction stir welding process is to join plates with dissimilar material. In this study, an attempt is made to find effects of tool offset, plunge depth, welding traverse speed and tool rotational speed on tensile strength, microhardness and material flow in dissimilar friction stir welding of AA1100 aluminium alloy and A441 AISI steel plates. Here, one factor at a time experimental design was utilised for conducting the experiments. Results indicated the strongest joint obtained at 1·3?mm tool offset and 0·2?mm plunge depth when the tool rotational speed and linear speed were 800?rev min^??1 and 63?mm min^??1 respectively. The maximum tensile strength of welded joints with mentioned optimal parameters was 90% aluminium base metal. Fracture locations in tensile test at all samples were in aluminium sides. Owing to the formation of intermetallic compounds at high tool rotational speed, the microhardness of joint interface goes beyond that of A441 AISI steel.     

An experimental and theoretical study of gas tungsten arc welding of stainless steel plates with different sulfur concentrations

During fusion welding, the presence of sulfur in steel often affects heat and fluid flow in the weld pool and its geometry. While the role of sulfur during welding of stainless steel plates with the same sulfur content is well understood, welding of stainless steel plates containing different concentrations of sulfur has not yet received proper attention. Here we report an experimental and modeling investigation of gas tungsten arc butt welding of stainless steel plates containing different sulfur concentrations. The main variables studied were sulfur concentrations in the two plates, welding current and welding speed. The results show significant shift of the fusion zone toward the low sulfur steel. The asymmetric fusion zone profile with respect to the original joint interface could be quantitatively explained through numerical modeling of heat transfer and fluid flow considering a bead shift observed experimentally.     

Numerical modelling and experimental determination of temperature distribution during manual metal arc welding

Abstract

Welding is a highly reliable and efficient metal joining process. Manual metal arc (MMA) welding is very widely used in industry. The temperature distribution that occurs during welding affects the material microstructure, hardness, and the residual stresses present in the material after welding. In the present work, the temperature distribution during bead on plate welding using MMA welding was experimentally determined for AISI type 304 stainless steel plates and low carbon steel plates of thickness 6 and 12 mm. A three-dimensional computer model based on the control volume method has been developed to predict the temperature distribution in the heat affected zone (HAZ) and in the base plate region of the bead on plate welds, using the weld parameters as input data to the computer model. In this computer model, the heat energy used to melt the electrode is considered as a separate heat flux term and the remaining heat supplied by the welding arc is considered as another heat flux term. A good match between the experimental results and the theoretical predictions was obtained. Using the computer model, the time taken to cool from 800 to 500°C in the coarse grained HAZ (close to the fusion line) of low carbon steel specimens was calculated. From this cooling time and the chemical composition of the material, the maximum hardness in the coarse grained HAZ was predicted. Microhardness measurement in the same region of the welded plates was carried out. The experimentally measured values and predicted results match closely.     

厚薄板对接单面焊双面成形自动焊机的研制

根据集装箱吊车箱形梁中厚薄板焊接要求,设计了一台专用自动焊接设备.针对不同厚度板的时接形式,采用单面焊双面成形技术,设计了独特的工件定位压紧和焊枪对中方式,实现了焊接过程的自动控制以及工艺参数设定存储和选用的数字化控制,保证了焊接过程稳定可靠,较好满足了生产需求.     

钛/钢复合板焊接技术研究现状及发展趋势

综合分析了已有钛/钢复合板焊接的研究成果,基于钛与钢焊接与连接的冶金特性,归纳总结并剖析了钛板搭接焊和对接焊、复合板过渡焊接工艺过程和焊缝金属冶金特点及相关力学性能,提出了未来钛/钢复合板焊接研究的重点发展方向及相关科学问题,希望对该领域的基础研究及工程应用提供有价值的参考.     

增材制造RAFM钢激光焊接头显微组织分析

局部工件采用增材制造技术成型再焊接完成装配是未来精密加工较为可行的方案之一. 采用激光焊对4种不同粒径粉末增材制造得到的低活化铁素体/马氏体钢板（reduced activation ferritic/martensitic steel,RAFM钢）进行焊接,分析激光焊接头显微组织演变特征.结果表明,粉末粒径小于25 μm的增材RAFM钢的道间未熔合缺陷在焊缝区得到修复,而热影响区与母材未熔合缺陷无法改善;粉末粒径为15 ~ 53,45 ~ 105 μm以及大于100 μm的增材RAFM钢的气孔缺陷在焊接过程中无法消除,焊缝区与母材皆有分布,后者的气孔数量和大小明显大于前两者;4种接头焊缝区微观组织皆为粗大的板条状马氏体,柱状晶生长至中心线相交,无等轴晶出现. 由增材制造工艺特点导致热影响区与母材区出现偏析带.近焊缝淬火区峰值温度较高,为细小的马氏体组织;远焊缝回火区产生二次回火的珠光体组织,且伴随部分晶粒长大.     

低碳钢与紫铜搅拌摩擦焊接头显微组织分析

用搅拌摩擦焊焊接了4 mm厚的Q235低碳钢板和T2紫铜板,得到了内部无缺陷、外观成形良好、无变形的对接接头.研究表明,低碳钢紫铜接头的显微组织与其所受到的热和力作用大小有关.在接头钢侧,轴肩挤压区有较大的变形,组织发生动态再结晶后形成了细小的等轴晶铁素体;在探针附近的热影响区,经历的应变较小,组织则由变形的先共析铁素体和侧板条铁素体组成.在接头铜侧热影响区的晶粒受热长大,而热力影响区的铜由于发生了动态再结晶,晶粒细小.在焊核区,上部主要由钢、铜薄层交叠组成;焊核中下部为钢、铜及钢与铜形成的化合物交叠组成的漩涡状条带,其中铜条带的组织为细小的等轴晶,钢条带的组织为细小的等轴晶或先共析铁素体 侧板条铁素体组织.     

基于弧压反馈的薄板GTAW智能熔透控制

薄板GTAW的熔透控制是保障其焊接质量的关键,而焊接熔透的智能传感与识别是其中的核心难题. 传统的焊缝背面直接视觉传感可以有效提取熔透控制信息,但是往往因为可达性受限而不能使用. 因此,文中对基于GTAW弧压电信号的传感焊接熔透进行研究,基于弧压反馈提取焊接熔透信号,进而调节焊接电流波形保证焊缝均匀熔透而不发生烧穿. 试验采用4 mm厚热轧钢板、3 mm厚冷轧钢板进行表面堆焊. 结果表明,在不同电流形式下堆焊试验中验证了控制原理,反馈智能调节,变散热条件以及变间隙试验均可得到较美观的焊缝.     

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.