ER50-6焊丝激光焊接Q345B/304异种钢接头组织与性能

目的 研究异种钢激光填丝焊接工艺对焊接组织与性能的影响规律,以降低Q345B/304异种钢激光焊接的成本,扩大异种钢激光焊接的应用范围,使其能够满足使用要求,实现Q345B/304异种钢激光焊接低成本的产业化应用。方法 采用便宜的ER50-6碳钢焊丝代替价格高昂的ER308L不锈钢焊丝以及不锈钢药芯焊丝对Q345B/304异种钢进行激光焊接,主要采用填丝ER50-6焊丝对5 mm厚的Q345B/304异种钢板进行激光焊接,再结合焊缝区、熔合区及热影响区的纳观-微观-宏观多尺度表征和测试结果,研究不同工艺参数下焊接接头的组织与结构,同时结合焊接工艺参数和多尺度的表征结果,研究焊接接头硬度、焊缝中元素分布、物相特征、力学性能的变化规律。结果 当激光功率为4.5 kW、焊接速度为6 mm/s、焊丝直径为1.2 mm、装配间隙为1 mm、送丝速度为2.5 m/min时,焊缝成形最好,且在焊缝中没有出现大量的M23C6和σ等有害相,焊接接头的力学性能等也完全满足使用要求。结论 采用ER50-6焊丝对Q345B/304异种钢进行激光焊接,能够得到完全符合质量要求的焊接接头,且降低了焊接成本。     

不同焊材匹配与时效处理对异种钢焊接接头显微结构与力学性能的影响

采用金相显微镜、万能试验机、冲击试验机、显微硬度计等对Q235/316L异种钢焊接接头的显微结构和力学性能进行研究。结果表明:在Q235/316L异种钢焊接中,以A042作为堆焊焊材,A022作为填充焊材,可使异种钢焊接接头的组织和力学性能得到提高;经300℃×2h保温,空冷时效处理后的异种钢焊接接头的综合性能优于500℃×2h,700℃×2h保温,空冷时效处理及不进行时效处理的异种钢焊接接头。这是由于铁素体、珠光体的存在使其屈服强度和抗拉强度得到了较大提高,同时,氢的消除及逆转变奥氏体数量的增加也使焊缝区和316LHAZ冲击韧性有所提高。     

T92/Super304H异种钢焊接接头的性能研究

根据新型耐热钢T92和Super304H钢的焊接特点制定了适宜的焊接工艺,研究了焊制的T92/Su-per304H异种钢焊接接头的力学性能。结果表明,T92/Super304H异种钢接头的各项力学性均能满足使用要求。焊缝金属的韧性远低于T92钢侧热影响区,焊缝金属的结晶形态对焊缝韧性有很大的影响。焊接接头中焊缝金属的硬度值最高,而T92钢侧热影响区硬度最低,并且不同热影响区部位显微硬度变化较大,Super304H钢侧热影响区硬度变化不大。     

Q235钢与1Cr18Ni9Ti不锈钢异种钢焊接接头性能的研究

主要研究Q235钢与1Cr18Ni9Ti不锈钢焊接中存在的焊缝金属化学成分不均匀和熔合区塑性降低(脆性层)这两个问题。采用焊条电弧焊进行焊接,然后对焊接接头进行宏观和微观研究。实验表明,制定合理的焊接工艺,可以在一定程度上控制热影响区晶粒的长大趋势,从而提高Q235和1Ci18Ni9Ti异种钢的焊接性。     

异种钢激光-电弧焊复合焊接数值模拟

目的研究异种钢激光-GMAW复合焊接温度场以及应力场变化。方法运用ANSYS有限元分析软件,以5 mm厚D500钢和A514钢为研究对象,采用均匀分布的柱体热源与椭球热源组合的方法,建立了激光-GMAW焊接热源模型,对异种钢激光电弧复合焊接过程进行了模拟计算,并与实验所得的焊缝形状以及焊后残余应力进行了对比。结果结果表明,异种钢激光电弧复合焊接过程焊接变形以及残余应力实验结果与数值计算结果吻合较好。结论验证了锥体加柱体热源与椭球热源的组合热源模型在异种钢激光-GMAW复合焊接温度场及应力场模拟中的适用性,从而为不同焊接工艺条件下异种钢激光-GMAW复合焊接的焊缝形状和尺寸预测,提供了一种有效的途径。     

FV520B钢和Q235A钢焊接接头的维氏硬度试验

在没有x-y轴移动装置的HV-120型维氏硬度计上,仅增加简单的辅助工具,成功完成了FV520B马氏体沉淀硬化不锈钢和Q235A钢V型焊缝焊接接头的维氏硬度试验。结果表明:FV520B钢焊接接头的焊缝、熔合线、热影响区以及母材的维氏硬度差别较小,硬度分布比较均匀,焊接质量满意;Q235A钢焊接接头的焊缝、熔合线、热影响区以及母材的维氏硬度差别更小,硬度分布更加均匀,焊接质量更好。该试验方法操作简单、方便实用,可以完成V型焊缝焊接接头的维氏硬度测试,对使用没有x-y轴移动装置的维氏硬度计的企业进行焊缝质量评定具有借鉴作用。     

30CrMnSiNi2A与Q235异种钢焊接接头组织与性能分析

目的探讨30CrMnSiNi2A与Q235异种钢焊接接头的组织与性能。方法采用手工电弧焊对两者进行焊接,为了获得性能良好的焊接接头,焊前对其进行焊前预热,焊后对其进行焊后退火。通过X射线探伤检测,拉伸、冲击试验,显微硬度检测及光学显微镜金相分析等一系列工艺试验,对焊接接头进行研究。结果焊缝质量等级达到Ⅰ级;焊缝组织为先共析铁素体、针状铁素体、珠光体组织;30CrMnSiNi2A侧热影响区组织为回火索氏体,粗晶区组织片层厚度大于细晶区组织片层厚度;Q235侧热影响区由不完全重结晶区、细晶区、粗晶区组成。结论 30CrMnSiNi2A与Q235钢焊接后,获得了工艺性、力学性能良好的接头,可运用于2种材料焊接的实际生产。     

镁/钢激光-电弧复合焊接接头的腐蚀行为

采用激光-电弧复合填丝对接焊方法获得了成形及力学性能良好的AZ31B镁合金/Q235钢板焊接接头;利用金相显微镜和电子探针观察焊接接头组织和元素分布状态,通过浸泡腐蚀试验和电化学试验研究了焊接接头不同区域(镁母材、焊缝、钢母材)的腐蚀行为。结果表明:AZ31B母材存在各向异性的腐蚀现象;焊缝与钢母材之间发生电偶腐蚀,邻近界面处的焊缝腐蚀严重,而界面处富集Al、Mn元素,腐蚀倾向较小;焊缝中存在较多钢飞溅,钢飞溅周围的区域比焊缝其他位置的腐蚀更为严重,焊接过程中产生的钢飞溅对焊缝的耐蚀性是不利的;焊缝中的β相一方面作为屏障层阻碍基体的腐蚀,另一方面作为电偶腐蚀中的阴极增加焊缝基体的腐蚀敏感性。     

外加直流磁场下微束等离子电弧行为与焊缝成形研究

为实现薄壁件金属在增材制造中成形及成性的精确控制,基于带电粒子在直流磁场作用下的运动规律,研究了外加直流磁场作用下电弧行为,得到电弧偏转程度、偏转方向与外加磁场之间的关系.在电弧偏转的基础上分析了焊缝形貌、焊缝晶粒变化原因.结果表明:外加直流磁场作用下电弧发生偏转,在试验参数范围内随磁场强度增加,电弧偏转程度增大,且电弧偏转方向与外加磁场方向相关;外加正向直流磁场时熔池向焊接方向后方偏移,焊缝余高相对增加,焊缝晶粒较无外加磁场细化;外加反向直流磁场时熔池位于电弧下方,焊缝余高相对降低,焊缝晶粒较外加正向磁场更加细化.外加正向直流磁场控制焊缝形貌,具有"控形"效果;外加反向直流磁场有明显的细化晶粒作用,可以达到"控性"目的.     

Q235焊接钢板受剪声发射时频特性分析

Q235钢板在工程中应用广泛,为了研究焊接对于Q235钢板性能的影响,开展了焊接试样和完整试样的受剪实验,利用数字声发射系统对实验过程的声发射信号进行实时采集。根据声发射计数率划分不同阶段,采用魏格纳-维尔分布,平滑伪魏格纳-维尔分布,对信号进行时频分析。实验结果表明:受剪实验中,焊接试样与完整试样的声发射特性明显不同,主要表现在受剪过程的各阶段中声发射信号能量集中的频带不同,弹性变形阶段信号时频带主要集中在80~100 k Hz附近;钢板塑性变形阶段时频带集中在100~140 k Hz范围内;焊缝塑性变形阶段,时频能量主要集中的频带范围在300~350 k Hz之间,部分能量较弱的信号分布在100 k Hz附近频段。     

不锈钢06Cr19Ni10和碳素钢Q235异种钢埋弧焊焊接工艺研究

根据生产过程中不锈钢06Cr19Ni10和碳素钢Q235-B异种钢板材的埋弧焊焊接问题,结合产品的结构特性和两种材料的焊接性,分析探索了异种钢材焊接的工艺方法,制定了切合实际生产的工艺方案,解决了生产成本高的难题。     

TP304H与12Cr1 MoV锅炉管异种钢的焊接

利用舍夫勒组织图对韶关发电厂SA2 13TP30 4H与 12Cr1MoV异种钢接头可能出现的焊接组织进行了分析 ,制订出了合理的焊接工艺 ,并对锅炉上的SA2 13TP30 4H与 12Cr1MoV钢焊口进行了施焊 ,经 17个月的运行 ,10 4个焊口未出现爆漏现象     

Chemical and Mechanical Characterization of AISI 304 and AISI 1010 Laser Welding

This paper addresses to the dissimilar laser welding of AISI 304 and AISI 1010 steel thin sheets. Cracks-free dissimilar edge fillet welds have been conducted using a Nd:YAG laser. Geometrical, microstructural, chemical, and mechanical proprieties of the welds were investigated using electron microscopy, EDS and tensile test assisted by digital image correlating. The proper results were achieved at an energy density of 88 J/mm² using a 0.4 mm laser spot diameter. An austenite-ferrite structure characterizes the weld bead and the precipitation of the chromium carbide at the grain limits was observed in the heat affected zone. Good tensile behavior was obtained; dissimilar joint was fractured on the carbon steel side at 482 MPa and 0.35 stain.     

固溶处理对304/Q245R焊接接头组织及性能的影响

为研究固溶处理对304奥氏体不锈钢和Q245R碳钢异种金属焊接接头显微组织及性能的影响,采用E309-16奥氏体不锈钢焊丝对6 mm厚的304/Q245R板材进行手工电弧焊,焊后使用箱式电阻炉对焊接接头进行固溶处理,对焊接接头进行显微组织观察和力学性能测试.结果表明:相对于固溶处理前,固溶处理后的接头焊缝组织为灰色奥氏体和黑色铁素体,枝晶偏析程度明显降低,Cr、Ni等合金元素分布较为均匀;焊缝和碳钢侧热影响区硬度值均有所提高,最高硬度值为304.59 HV,出现在焊缝位置;接头抗拉强度较高,达570 MPa,拉伸断裂发生在母材Q245R碳钢部位.另外,对焊缝进行XRD测定,未检测到不利于接头性能的相,这表明固溶处理后的异种金属接头性能良好,能够满足工程中的实际需求.     

Development of EPRI P87 solid wire

Abstract

Dissimilar metal welds (DMW’s) between ferritic and austenitic materials at elevated temperatures have concerned boiler manufacturers and operators for decades because of the proven potential for premature failure. The industry has desired an improved filler metal that would minimize or eliminate DMW failures and, with the current trend toward higher boiler steam pressures and temperatures, have suitable creep strength for joining higher strength materials such as Grade 91 steels After years of research, the Electric Power Research Institute (EPRI) concluded the development and commercialization of a nickel-based filler metal, EPRI P87, for application in shielded metal arc welding (SMAW). This work describes the subsequent development of an EPRI P87 solid wire welding product for application in gas tungsten arc and gas metal arc welding (GTAW and GMAW) processes, and the initial research into the performance of DMWs produced with the new solid wire P87 product. A 135 kg heat of solid wire was produced and tested using various welding processes and evaluation methods to ensure that the material would meet required weldability and design specifications. Welding methods included GMAW-P, GTAW and hot-wire GTAW in welds up to 50mm in thickness. The weld joint tested was a dissimilar metal weld of grade 91 to 347H, which was assessed using microstructure evaluation, creep testing, hot tensile testing, circular patch, and edge build-up investigations to examine hot-cracking susceptibility. This paper summarizes the research completed to date on the EPRI 87 filler wire which supports the acceptability of this material for its intended use in high-temperature power generation applications.     

Crack resistance of austenitic stainless steel pipe and pipe welds with a circumferential crack under monotonic loading

This paper describes the experimental studies carried out on cracked austenitic stainless steel pipe and pipe welds under bending loads. Pipe welds were produced by gas tungsten arc welding (GTAW) and shielded metal arc welding (SMAW). Fracture resistance curves for pipe and pipe welds were compared. Results indicate that the fracture resistance of pipe and pipe weld (GTAW) is comparable but that of pipe weld (GTAW+SMAW) is inferior. Cracks do not deviate from their original plane during propagation as observed in the cases of carbon steel pipe and pipe welds. The fracture resistance of pipe welds does not depend on the loading histories to which it has been subjected prior to fracture test. Initiation and crack propagation were observed prior to the maximum moment. An existing limit load expression is applicable for the pipe base material but gives non‐conservative results for the pipe welds. Multiplication factors have been suggested for the pipe welds for evaluation of limit loads using the existing expression. Fracture resistance for the pipe and compact tension specimens have also been compared for base material and welds.     

Ductile fracture mechanisms in shielded metal-arc and gas tungsten-arc welds of Type 347 stainless steels

The ductile fracture behavior of two different welds of Type 347 stainless steel, which are made by SMAW (shielded metal arc welding) and GTAW (gas tungsten arc welding) processes was characterized by J-integral testing and microstructural evaluation techniques. Both welds by SMAW and GTAW processes showed significantly low fracture toughness compared with that of the base metal. Metallographic and fractographic examinations revealed that different micromechanisms are operative in the fracture process of the two welds. In the SMAW weld, the fracture was dominated by void initiation and growth at the inclusions that are homogeneously distributed in the matrix. On the other hand, in the GTAW weld, a large number of Nb(CN) particles precipitated on the austenite/ferrite interface as long rod shapes and the fracture proceeded by void initiation at these particles and accompanying decohesion of the interface. It is recommended that the C and Nb contents be reduced in weld metal itself as well and that the welding atmosphere be controlled.     

Microstructure and mechanical properties of dissimilar materials joints between T92 martensitic and S304H austenitic steels

In this paper, T92 martensitic steel and S304H austenitic steel were welded by gas tungsten arc welding (GTAW) process. Microstructural features and mechanical properties of T92 and S304H dissimilar materials joints were investigated. The results showed that the part of the joints with relatively weak tensile strength was T92 coarse-grained heat affected zone (CGHAZ), while the part of the joints which revealed relatively weak toughness was weld metal. The decrease of tensile strength in T92 CGHAZ was due to its coarse tempered martensite structure. Weak toughness of the joints was resulted from the coarse dendritic austenite of the weld metal. However, the weld metal in transverse direction of the joints was provided higher tensile strength by the orientation distribution of grains compared with T92 CGHAZ.     

Weldability and properties of martensitic/austenitic stainless steel joints

Abstract

A series of studies has been carried out to examine the weldability and properties of dissimilar steel joints using martensitic and austenitic stainless steels F6NM (OCr13Ni4Mo) and AISI 347, respectively. This type of joint requires good mechanical properties, corrosion resistance, and a stable magnetic permeability in addition to a good weldability. Weldability tests include weld thermal simulation of the martensitic steel to investigate the influence of weld thermal cycles and post-weld heat treatment (PWHT) on the microstructure and mechanical properties of the heat affected zone (HAZ); implant testing to examine the tendency for cold cracking of martensitic steel; and rigid restraint testing to determine hot crack susceptibility of the multipass dissimilar steel joints. The simulation results indicated that the toughness of the martensitic steel HAZ did not change significantly after the weld thermal cycles. The implant test results indicated that welds produced using nickel based filler show no tendency for cold cracking, whereas welds produced using martensitic or ferritic filler show such a tendency. Based on the weldability tests, a welding procedure (tungsten inert gas welding for root passes with HNiCrMo-2B wire followed by manual metal arc welding using ENiCrFe-3B coated electrode) was developed and a PWHT at 600°C for 2 h was recommended. Joints produced using the developed welding procedure are not susceptible to hot and cold cracking. After PWHT the joints exhibit both satisfactory mechanical properties and stress corrosion cracking resistance.

MST/1955     

Prediction of residual stresses in welds of similar and dissimilar steel weldments

The fabrication of structural member using dissimilar steels renders steel structures lighter and more economical. However, it always involves welding process and produces different residual stresses in welds as compared with welding of similar steels. This paper presents the characteristics of residual stresses in welds of similar and dissimilar steel weldments by carrying out three-dimensional (3-D) thermal elastic-plastic finite element (FE) analysis. The materials used in this investigation were SM400, SM490, SM520 and SM570, widely used structural steels in welded structure. Results show that the maximum longitudinal residual stresses in welds of the similar steel weldments increase with increasing yield stress of the steel welded (SM400 < SM490 < SM520 < SM570). In case of the dissimilar steel weldments, the difference between the longitudinal residual stresses in welds increases with increasing yield stress of the steel welded together with SM400 (SM490 < SM520 < SM570).