大线能量焊接用结构钢的研究进展

大线能量焊接钢板具有广阔的市场前景，已成为厚板的发展趋势。本文综述了目前国内外提高钢大线能量焊接性的主要技术手段，介绍了大线能量焊接用结构钢的开发应用情况，为大线能量焊接钢板的开发提供借鉴。     

首钢储罐用钢SG610E大线能量焊接性分析

为满足国内对大线能量用钢的需求,首钢开发了用于大型石油储备罐建设的大线能量钢板SG610E。并对其进行了大线能量焊接性研究工作,结果表明,大线能量钢板SG610E经线能量100kJ/cm气电立焊后,焊接接头在-20℃下仍具有优良的低温韧性,钢板可用于建造大型石油储罐。     

沙钢打破国外垄断成功研制大线能量焊接船板

沙钢打破日本在大线能量焊接钢板领域的长期垄断,日前大线能量焊接船板在沙钢研制成功。据沙钢新闻,这是从钢铁研究院传来的喜讯,由焊接研究室负责的大线能量焊接船板项目取得突破性进展,通过采用焊接线能量150～400 kJ/cm的气电立焊方     

大型原油储罐用WH610D2钢板的性能

介绍了为制造大型原油储罐而专门开发的WH610D2钢板优良的力学性能、焊接性能和抗硫化氢应力腐蚀性能，该钢种特别适合于大线能量焊接。     

日本海洋平台用厚板开发现状

介绍了日本JFE公司、新日铁公司及住友金属公司海洋平台用钢板的开发现状,重点介绍日本钢铁公司海洋平台用钢板系列化品种、焊接热影响区的韧化及先进的轧制工艺。并针对我国海洋平台用钢开发滞后的局面,指出了未来的重点是按照国际海洋工程用钢的4个标准,成系列开发海洋平台用钢板,如高强钢板、大线能量焊接钢板、低温及耐海水腐蚀钢板等系列产品,并开发独有的焊接热影响区韧化技术及焊接技术。     

大线能量焊接DH36钢焊接热影响区组织与性能研究

利用双丝埋弧焊接试验,对比分析了传统DH36钢和大线能量焊接DH36船板钢焊接热影响区的组织与性能。结果表明,利用新型的Ti处理技术生产的大线能量DH36钢母材具有良好的强韧性和大线能量焊接性。经大线能量(100 kJ/cm)焊接后,传统DH36钢焊接热影响区低温韧性显著降低,不能满足指标要求(34 J)。大线能量DH36船板钢在50 kJ/cm和100 kJ/cm热输入焊接时均表现出良好的低温韧性,-20℃冲击功大于100 J。同传统的DH36钢相比,大线能量DH36钢焊接接头出现了软化区,但接头强度并未显著下降。总体上大线能量焊接DH36钢优越性在于:大线能量焊接时,焊接热影响区主要得到大量交错排列的晶内针状铁素体组织,热影响区硬度降低,低温韧性显著提高。     

大线能量低焊接裂纹敏感性钢的显微组织

简要叙述了新研制的大线能量焊接低焊接裂纹敏感性调质高强度钢的特点.研制的新钢种属低碳低合金高强钢,集高强度(σs≥490 MPa、σb≥610 MPa)、高韧性(-20℃时横向Akv≥47 J)、优异的焊接性能(厚度≤50 mm钢板焊前不需预热或稍加预热而不产生冷裂纹)于一体,并能承受大线能量(≥50 kJ/cm)焊接.研究了模拟焊接热影响粗晶区(CGHAZ)的微观组织结构特征及其与力学性能的关系.结果表明:CGHAZ中复合夹杂物可促进针状铁素体的形成,针状铁素体的数量与输入线能量有关并显著影响CGHAZ的力学性能.     

大线能量焊接船体钢的研究

大线能量焊接时由于高温停留时间长、相变冷却速度慢,焊接热影响区奥氏体晶粒急剧长大,得到侧板条铁素体为主的组织,韧性恶化。降低钢中的C含量及碳当量(Ceq)、细化焊接热影响区奥氏体晶粒尺寸以及改善焊接热影响区的组织是发展大线能量焊接用钢的主要技术措施。"氧化物冶金"技术利用钢中细小的氧化物,通过促进晶内针状铁素体形核明显改善焊接热影响区的组织,成为大线能量焊接用钢最有效的技术途径。实验结果表明:Ti-Mg复合处理明显细化钢中氧化物颗粒尺寸,促进了晶内针状铁素体形核,在100～200kJ/cm的大线能量焊接条件下粗晶热影响区得到针状铁素体为主的组织,-20℃冲击功达到350J。     

焊接线能量对T91钢焊缝组织及硬度的影响

采用不同的焊接线能量对T91钢进行焊接,并对回火后的焊接接头分别采用三氯化铁盐酸水溶液和硝酸酒精溶液浸蚀,微观组织观察表明,不同焊接线能量下经三氯化铁盐酸水溶液浸蚀后焊接接头均为板条马氏体组织,而经硝酸酒精浸蚀后焊接接头均为索氏体组织,晶界清晰,大线能量焊接会引起焊缝及热影响区晶粒边界碳化物聚集.硬度测试结果表明,大线能量焊接热处理后焊接接头的硬度高于小线能量焊接的焊接接头硬度.     

焊接线能量对船板钢HAZ冲击韧性的影响

针对焊接线能量对船板钢HAZ冲击韧性的影响开展了包括冲击试验、断口分析和显微组织分析等一系列的研究。结果表明,在-20℃下,16和40 mm厚的钢板在大线能量焊接后HAZ冲击吸收能量均超过160 J,而25 mm的冲击吸收能量为57.5 J;16和40 mm厚的钢板热影响区断口为典型的韧性断裂,25 mm厚的钢板为准解理断裂。在显微组织方面,三种厚度钢板的热影响区均诱发了大量的晶内针状铁素体,使组织细化,甚至优于原板组织。25 mm厚钢板热影响区的冲击韧性相对较差,其原因一方面是所承受热负荷较大,另一方面则是其母板的组织相对粗大。     

坡口预留间隙对高强度钢厚板打底焊缝成形的影响

利用MSC. Marc有限元分析软件对低合金高强度钢厚板打底焊热过程进行数值模拟,从温度场角度分析坡口预留间隙大小对焊缝根部熔合的影响,并通过焊接试验对模拟结果进行验证和补充. 结果表明,在低合金高强度钢要求的焊接热输入下,当预留间隙小于2 mm时,打底焊缝根部出现未熔合或未焊透缺陷;当预留间隙增大到2~4 mm时,打底焊缝根部熔透,焊缝成形良好;当间隙增大到5 mm以上后,热源不足以熔化较多的侧壁母材金属,可能出现未熔合,实际焊接时需要采用大热输入摆动才能熔合良好.     

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.     

海上风电维护平台用FH46低温钢的焊接工艺

风电平台升降系统常采用大厚度FH46低温钢,该材料焊接难度较大,低温服役要求苛刻。通过焊接性分析和焊接工艺评定,制定了有效可行的工艺措施,包括焊接材料和焊接方法的选择,焊接热输入、焊前预热和焊后热处理参数的制订。结果证明,该工艺满足劳氏船级社(LR)海工平台规范要求,为该类低温钢焊接施工积累了实用经验。     

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.     

Effects of welding parameters and tool geometry on properties of 3003-H18 aluminum alloy to mild steel friction stir weld

Defect-free butt joints of 3003 Al alloy to mild steel plates with 3 mm thickness were performed using friction stir welding (FSW). A heat input model reported for similar FSW was simplified and used to investigate the effects of welding speed, rotation speed and tool shoulder diameter on the microstructure and properties of dissimilar welds. The comparison between microstructure, intermetallics and strength of welds shows the good conformity between the results and the calculated heat input factor (HIF) achieved from the model. The joint strength is controlled by Al/Fe interface at HIF of 0.2–0.4, by TMAZ at HIF of 0.4–0.8 and by intermetallics and/or defects at HIF>0.8.     

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.     

Double-Sided Single-Pass Submerged Arc Welding for 2205 Duplex Stainless Steel

The duplex stainless steel (DSS), which combines the characteristics of ferritic steel and austenitic steel, is used widely. The submerged arc welding (SAW) method is usually applied to join thick plates of DSS. However, an effective welding procedure is needed in order to obtain ideal DSS welds with an appropriate proportion of ferrite (δ) and austenite (γ) in the weld zone, particularly in the melted zone and heat-affected zone. This study evaluated the effectiveness of a high efficiency double-sided single-pass (DSSP) SAW joining method for thick DSS plates. The effectiveness of the converse welding procedure, characterizations of weld zone, and mechanical properties of welded joint are analyzed. The results show an increasing appearance and continuous distribution feature of the σ phase in the fusion zone of the leading welded seam. The converse welding procedure promotes the σ phase to precipitate in the fusion zone of leading welded side. The microhardness appears to significantly increase in the center of leading welded side. Ductile fracture mode is observed in the weld zone. A mixture fracture feature appears with a shear lip and tears in the fusion zone near the fusion line. The ductility, plasticity, and microhardness of the joints have a significant relationship with σ phase and heat treatment effect influenced by the converse welding step. An available heat input controlling technology of the DSSP formation method is discussed for SAW of thick DSS plates.     

大热输入焊接EH36船板钢接头力学性能

以EH36高强度船板钢为研究对象,通过拉伸和冲击分析试验手段,对EH36船板钢不同热输入埋弧焊接头进行了力学性能测试,同时采用扫描电镜对冲击试样断口形貌进行分析.结果表明,所有断裂均发生在拉伸试样的母材区,EH36船板钢在大焊接热输入条件下,焊缝和焊接热影响区的强度好于母材,并没有出现热影响区软化现象;随着焊接热输入增加焊缝的冲击韧性降低,从焊缝和熔合区断口形貌来看,断裂类型为韧性断裂和准解理断裂的混合断裂.随着远离熔合线距离的增加,冲击吸收功有增加的趋势,在距离熔合线4 mm处的冲击吸收功跟母材接近,说明该位置处韧性基本不受焊接热循环的影响.