热处理对N02201/Q345R复合板接头组织及性能的影响

采用GTAW+SMAW组合方法焊接了N02201/Q345R镍钢复合板,截取两组同规格试板,其中一组为焊态,另一组进行550℃保温4 h热处理。通过拉伸试验和弯曲试验测试并对比了接头力学性能,同时利用OM对焊接接头微观组织进行表征对比。结果表明:焊态和热处理态N02201/Q345R复合板接头力学性能均满足标准和使用要求,热处理后接头抗拉强度仅降低49 MPa;N02201/Q345R复合板接头焊态和热处理态钢侧为铁素体和珠光体组织,镍侧为单相奥氏体,镍钢界面存在镍元素向钢侧扩散现象,焊态扩散层宽度约为0~25μm,热处理态扩散层宽度约为100~160μm。     

细晶Q345低合金高强钢焊接接头组织性能研究

采用埋弧自动焊法对30 mm细晶Q345C低合金高强钢进行焊接,用金相显微镜观察焊接接头微观组织,并检验接头拉伸、弯曲及冲击性能。结果表明,细晶Q345母材由晶粒细小的铁素体和珠光体构成,焊接接头焊缝金属与母材强度相似。焊缝外观平整、组织均匀,焊缝和热影响区均具有良好的冲击韧性,焊接接头可以满足使用要求。     

Q345级钛氧化物冶金钢生产工艺及大线能量焊接性能研究

研究了工业化条件下钛氧化物冶金和TMCP工艺对Q345级钢板基体力学性能及大线能量焊接性能的影响。采用光学显微镜、扫描电镜、电子探针等手段分析了钢板显微组织及夹杂物特征,进行了大线能量焊接热模拟和气电立焊试验。结果表明,在钛氧化物冶金和TMCP工艺下,工业化试制钢板获得了良好的基体力学性能和大线能量焊接性能。钢中Ti、Mg、Ca等微细氧化物或氧硫化物均匀弥散分布,有效促进了焊接粗晶热影响区针状铁素体组织形成,200 kJ/cm线能量下焊接接头冲击韧性显著改善。     

不同冷速下钛微合金化Q345B钢的HAZ组织及性能

焊接热影响区(HAZ)的微观组织很大程度上决定了钢材焊接处的力学性能。为了掌握含钛微合金钢Q345B在不同焊接线能量下热影响区的微观组织及性能演变规律,采用Gleeble 3500热模拟试验机,对含钛微合金钢Q345B焊接过程中热影响区的组织演变进行模拟试验研究,分析了冷却速率对热影响区的微观组织及冲击韧性的影响。结果表明,大线能量焊接低冷速下热影响区组织以粒状贝氏体为主,t8/5为120 s时,析出针状铁素体,针状铁素体的出现有利于焊接热影响区冲击韧性的提升。     

正火态压力容器用Q345R工业开发

针对压力容器用Q345R钢板正火态条件下的微观组织和力学性能进行研究,通过优化成分设计、合理控制冶炼、轧制及热处理工艺,成功开发了正火态压力容器用高强度Q345R用钢。试验结果表明:正火态的钢板组织更均匀致密,冲击韧性优异,拉伸性能更稳定,满足压力容器相关标准要求。     

稀土对低合金高强度结构钢Q345E疲劳性能的影响

文章对比分析了稀土元素对低合金高强度结构钢Q345E焊接接头力学性能及金相组织的影响,从稀土元素对Q345E的晶粒度和夹杂物控制方面分析了稀土对母材及焊缝疲劳性能的影响。     

210mm厚度Q345R压力容器特厚板的研制

采用合理的成分和优化的工艺,开发出厚度为210 mm的Q345R压力容器特厚板,Q345R成分设计是在Q345碳钢的基础上添加适量微合金元素Nb、V、Ti,炼钢工艺采用铁水预处理脱S、LF+RH精炼,连续铸造成厚度为320 mm的坯料,通过2块320 mm坯料真空焊接,合理的加热温度、高温低速大压下控制轧制工艺、轧后堆垛缓冷、正火热处理等工艺,生产出力学性能优良、内部质量良好的Q345R特厚容器板。     

C-Mn-Ti系Q355B钢板的试制

低合金高强钢因其应用环境以及使用条件的特殊性，常常需要具有良好的力学性能。微合金化结合一定的热处理工艺，可以有效提高低合金高强钢的性能。研究钛微合金化及热处理工艺对低合金高强钢组织和性能的影响规律及作用机理，对提高材料的性能、扩大材料的应用具有重要的意义。以C-Mn-Ti系Q355B板坯的试制过程为例，研究了钛微合金化冶金成分及轧制工艺控制对材料显微组织和力学性能的影响规律；对比了4种不同轧制工艺条件下所生产钢板的力学性能和金相微观组织；并分析了材料的强化机制。0℃和20℃时Q355B板的低温冲击性能、屈服强度和冷弯性能分析结果表明，冶炼过程中形成的较大尺寸的TiN和链状的Ti₄C₂S₂对钢板的塑性和韧性均有负面影响；Ti微合金化后的钢板晶粒度均在9级以上；精开轧温度低于890℃,终冷温度在660±20℃波动时，钢板的综合力学性能最好。     

2219铝合金及变极性等离子接头的低温力学性能

通过拉伸试验．测定了2219-T87铝合金母材及其变极性等离子焊焊接接头不同温度下的力学性能。利用光学昆微镜与扫描电镜等手段,对母材和焊接接头的微观组织及断口形貌进行了观察和分析,研究了低温对母材和焊接接头性能的影响。试验结果表明,该铝合金具有低温增强增韧现象,适用于低温条件下工作;VPPAW接头强度塑性提高的同时低温延伸率变化不大。探讨了低温对母材及焊接接头性能的影响机理。     

Q345B-Fr建筑耐火钢焊接性及焊接接头组织性能研究

介绍了鞍钢开发的建筑耐火结构钢Q345B—Fr的焊接性及焊接接头的组织性能。使用相匹配的E5015NiMo手工焊条,焊接接头具有良好的综合力学性能和抗高温强度,在600℃保温2h条件下,高温强度大于常温强度的2／3。     

Analysis of Metallurgical and Mechanical Properties of Continuous and Pulsed Current Gas Tungsten Arc Welded Alloy C-276 with Duplex Stainless Steel

The present work investigates the microstructure and mechanical properties of alloy C-276 fabricated by continuous and pulsed current gas tungsten arc welding process and by employing ER2553 filler wire. Optical and scanning electron microscopic analyses were carried out to study the microstructures of weldments produced. Energy dispersive X-ray spectroscopy (EDS) was performed to investigate the formation of secondary phases in the weldments. The results disclosed that pulsed current gas tungsten arc welding showed refined microstructure compared to continuous current gas tungsten arc welding. SEM/EDS analysis revealed the segregation of Mo in the weld interface regions in both the welding techniques. The extent of microsegregation reduced the strength and toughness of the weld joint compared to the base metal. Bend test revealed cracks in the weld interface region in both the weldments.     

屈服强度460MPa级耐候钢及其焊接性能

通过连续冷却相转变行为的研究,利用试验轧机成功试制了24mm厚,屈服强度460MPa级耐候钢板,并分析了钢板微观组织、力学性能、腐蚀性能以及焊接性能。连续相转变行为和钢板试制结果表明:精轧温度不大于850℃,厚度压下率不小于0.6,冷速为4~15℃/s和终冷温度不大于465℃可得到以针状铁素体(3~10μm)和多边形铁素体(5~15μm)为主的钢板,其屈服强度不小于480MPa,抗拉强度不小于635MPa,伸长率不小于23%,-40℃冲击功不小于209J。对试制钢板进行了热输入量为72kJ/cm的双丝埋弧焊接试验,无焊前预热和焊后热处理,得到了无缺陷焊接接头,焊接热影响区-40℃冲击功不小于100J;粗晶区的高韧性与其晶内铁素体为主以及少量晶界铁素体和上贝氏体的微观组织有关。72h周浸试验结果表明:试制钢种的耐大气腐蚀能力比普碳钢Q345B提高了46%。     

Research on the Welding Process of 590MPa Grade High Strength Automobile Beam Steel

590 MPa automobile beam steel strips are used mainly to manufacture the longitudinal beam of trucks.It’s welding properties are critical to the safety of truck.The microstructure and mechanical properties of welding joints processed by CO 2 arc welding with different welding parameters were studied.The results showed that the welding joints were weak when welding heat input were small and the non metal inclusions were found in the weld joints when welding heat input are big.The quality of the welding joints is good enough at 170A of the arc current and 24V of the arc voltage.Keeping the other welding parameters fixed,the incomplete fusion defect occurred in the welding joint with backward welding,but the quality of the welding joint is good with forward welding.     

Laser Welding of Ultra-Fine Grained Steel SS400

Steeliswidelyusedbecauseofitsgoodcompre hensive properties ,plentyofresourceandlowerprice .Thestrengthandtoughnessaretwoimpor tantpropertiesofsteels ,andpeoplemakeeffortstoincreasetheirvalues .Addingalloyingelementandcontrollingmicrostructurearetwobasicwaystoac complishtheaim .Therefinedmicrostructureob tainedbyprocessingtechniqueenablesthestrengthandtoughnessofsteeltobeincreasedwithoutaddingalloyingelementandtheratioofperformance costtobeincreased .Theultra finegrainedsteelshavefer ritegrains…     

Characteristics of a pulsed-current, vertical-up gas metal arc weld in steel

The performance of the pulsed-current gas metal arc welding (GMAW) process for vertical-up weld deposition of steel has been found to be superior over the use of the short-circuiting arc GMAW process with respect to the tensile, impact, and fatigue properties of the weld joint. The microstructure, weld geometry, and mechanical properties of a pulsed-current weld joint are largely governed by the pulse parameters, and correlate well to the factor φ, defined as a summarized influence of pulse parameters such as peak current, base current, pulse-off time, and pulse frequency. The increase of φ has been found favorable to refine the microstructure and enhance the tensile strength, C _v toughness, and fatigue life of a weld joint. The fatigue life of a short-circuiting arc weld joint has been found to be markedly reduced due to the presence of an undercut at the weld toe and incomplete side-wall fusion of the base material.     

Effect of Activated Flux on the Microstructure, Mechanical Properties, and Residual Stresses of Modified 9Cr-1Mo Steel Weld Joints

A novel variant of tungsten inert gas (TIG) welding called activated-TIG (A-TIG) welding, which uses a thin layer of activated flux coating applied on the joint area prior to welding, is known to enhance the depth of penetration during autogenous TIG welding and overcomes the limitation associated with TIG welding of modified 9Cr-1Mo steels. Therefore, it is necessary to develop a specific activated flux for enhancing the depth of penetration during autogeneous TIG welding of modified 9Cr-1Mo steel. In the current work, activated flux composition is optimized to achieve 6 mm depth of penetration in single-pass TIG welding at minimum heat input possible. Then square butt weld joints are made for 6-mm-thick and 10-mm-thick plates using the optimized flux. The effect of flux on the microstructure, mechanical properties, and residual stresses of the A-TIG weld joint is studied by comparing it with that of the weld joints made by conventional multipass TIG welding process using matching filler wire. Welded microstructure in the A-TIG weld joint is coarser because of the higher peak temperature in A-TIG welding process compared with that of multipass TIG weld joint made by a conventional TIG welding process. Transverse strength properties of the modified 9Cr-1Mo steel weld produced by A-TIG welding exceeded the minimum specified strength values of the base materials. The average toughness values of A-TIG weld joints are lower compared with that of the base metal and multipass weld joints due to the presence of δ-ferrite and inclusions in the weld metal caused by the flux. Compressive residual stresses are observed in the fusion zone of A-TIG weld joint, whereas tensile residual stresses are observed in the multipass TIG weld joint.     

Effect of Arc Welding Processes on the Weld Attributes of Type 316LN Stainless Steel Weld joint

The present study aims at understanding the effect of various arc welding processes on the evolution of microstructure, mechanical properties, residual stresses and distortion in 9 mm thick type 316LN austenitic stainless steel weld joints. Weld joints of type 316LN stainless steel were fabricated by three different arc welding processes which were commonly employed in the nuclear industry. All the weld joints passed radiographic examination. Microstructural characterization was done using optical and scanning electron microscope. Volume fraction of δ-ferrite was lowest in the A-TIG weld joint. The A-TIG welded joint exhibited adequate strength and maximum impact toughness values in comparison to that of weld joints made by SMAW and FCAW processes. The A-TIG weld joint was found to exhibit lowest residual stresses and distortion compared to that of other welding processes. This was attributed to lower weld metal volume and hence reduced shrinkage in the A-TIG weld joint compared to that of weld joints made by FCAW and SMAW processes which involved v-groove with filler metal addition. Therefore, type 316LN stainless steel A-TIG weld joint consisting of lower δ-ferrite, adequate strength, high impact toughness, lower residual stresses and distortion was suited better for elevated temperature service compared to that of SMAW and FCAW weld joints.     

不同强度级别低合金钢焊缝金属的组织特征及其对韧性的影响

焊接区的微观组织是决定其力学性能的关键因素。为了改善低合金钢焊缝的冲击韧性,对500~1 000MPa级焊条的焊缝金属的化学组成、金相组织和力学性能进行了对比研究。采用金相显微镜和透射电子显微镜对不同强度级别的低合金钢焊缝组织进行了观察和电子衍射分析,并进行了焊缝金属拉伸强度和冲击韧性测试。结果表明,随着焊条强度级别的增加,焊缝组织由先共析铁素体、针状铁素体加珠光体变成粒状贝氏体,最后变成贝氏体加马氏体组织;当焊缝组织为粒状贝氏体时其韧性最低。     

Effect of current pulses on the temperature distribution and microstructure in TIG tantalum welds

The welding process employed for bonding metals by melting and solidification produces a joint which is generally inhomogeneous. The micro structure of the fused zone and its adjacent heat affected zone, HAZ, is usually different from the microstructure of the parent metal, obtained by mechanical working or heat treatment. The fused zone is usually composed of coarse columnar grains characteristic of as-cast structures. If the parent metal was originally cold-worked, recrystallization will occur in the HAZ, producing a coarse grained structure. As a result of the effect of the microstructure on the mechanical properties of the weld, the obtained joint may be weaker than the rest of the structure which was not affected by the heat of the welding. Although in some cases it is possible to improve the properties of the weld by post-welding heat treatment, different methods are tried in order to improve the microstructure directly during the welding process.     

Q345B热轧带钢冷弯开裂成因分析

针对热连轧厂生产的Q345B冷弯型钢用钢带在生产矩形管过程中出现的焊缝开裂、热影响区压扁开裂和弯曲弧开裂问题,通过对Q345B带钢成分、组织、夹杂物、气体、硫偏析等检验、分析以及对焊接工艺研究,得出焊接工艺不合理是造成焊缝开裂和热影响区压扁开裂的主要原因;原料中夹杂物多、带钢中存在的孔洞(或微裂纹)是造成弯曲弧开裂的主要原因。通过改进焊接工艺、减少钢中硫含量和提高钙处理效果等提高了矩形管合格率。