旋转速度对6061-T6铝合金高速搅拌摩擦焊接头组织与性能的影响

在高焊接速度(3 000 mm·min^-1)下分别对3 mm和4 mm厚6061-T6铝合金板进行搅拌摩擦焊,研究了高旋转速度(4 000～6 000 r·min^-1)对接头组织与拉伸性能的影响。结果表明：旋转速度越小越容易产生孔洞缺陷,旋转速度越大越容易出现过热氧化现象,增大旋转速度有利于接头区域再结晶形成致密组织,4 mm厚铝合金板焊接接头的焊接缺陷较3 mm厚铝合金板焊接接头严重;3 mm厚铝合金板在5 000 r·min^-1旋转速度下的焊接接头质量最好,拉伸性能最佳,抗拉强度和断后伸长率分别为265.82 MPa, 4.58%;4 mm厚铝合金板在6 000 r·min^-1旋转速度下的焊接接头质量最好,拉伸性能最佳,抗拉强度和断后伸长率分别为212.14 MPa, 4.03%。     

焊接次数对TC18钛合金中厚板电子束焊接接头组织及性能的影响

采用电子束焊接工艺对21 mm厚TC18钛合金板进行了1次与2次(在1次焊接焊缝处以相同工艺再次焊接)焊接试验,研究了焊接次数对接头组织、拉伸性能和硬度的影响。结果表明：2种焊接接头均成形良好,无明显缺陷;相对于1次焊接,2次焊接接头热影响区中的α′相增多,晶粒尺寸增大;焊接接头的抗拉强度高于母材,且2次焊接接头强度更高,但断后伸长率下降,断裂方式均为韧性断裂;1次焊接与2次焊接接头焊缝区的平均显微硬度分别为380,395 HV,均高于母材区,热影响区的平均显微硬度分别为360,350 HV,增加焊接次数提高了焊缝区硬度,降低了热影响区硬度。     

锻造ZK60镁合金的搅拌摩擦焊工艺

采用搅拌摩擦焊焊接工艺对4 mm厚的锻造ZK60镁合金板进行了焊接试验,研究了搅拌头轴肩尺寸、旋转速度及焊接速度等对焊缝质量及接头抗拉强度的影响,并得到了较佳焊接工艺参数。结果表明:在其他条件一定时,焊接接头的抗拉强度随搅拌速度的增加而增大,随焊接速度的增加而先增大后减小;当搅拌头轴肩直径为15 mm、旋转速度为1 170 r.min-1,焊接速度为36 mm.min-1时,所得焊缝表面光滑,无裂纹、孔洞、疏松及未焊透等缺陷,接头的抗拉强度最大,为271.2 MPa,约为母材的85%。     

5R60铝合金焊接接头微观组织与力学性能研究

针对中国兵器工业集团第五二研究所开发的高性能5R60铝合金在应用中对熔焊的需求,使用五二所研发的?1.6mm高性能5R59铝合金焊丝,采用MIG焊接方法焊接13mm厚5R60铝合金板材,并对焊接接头显微组织、断口形貌、拉伸力学性能和显微硬度等内容进行研究。研究结果表明：焊缝区和靠近焊缝一侧的热影响区晶粒为均匀细小的等轴晶,平均晶粒尺寸分别为9.6和18.4μm;焊缝组织中分布大量由Al、Sc、Zr、Ti元素组成的初生第二相,该相对提升促进焊缝组织晶粒细化、提升接头强度具有积极作用;显微硬度测试结果分析焊接接头热影响区宽度约为30mm;焊接接头最高抗拉强度和延伸率分别为367MPa和13%,平均抗拉强度和延伸率分别为358.3MPa和12.5%;焊缝区由于铸态组织缺陷成为性能最薄弱区域,平均显微硬度为90.5HV。     

高氮钢电子束焊接接头组织与性能分析

高氮钢焊接技术的研究是高氮钢研制和应用的关键技术之一。采用真空电子束焊接方法,对4 mm厚的高氮钢进行了焊接,研究了焊接接头的组织和力学性能。研究结果表明高氮钢电子束焊接焊缝和热影响区的组织为奥氏体组织,当焊接束流为20 m A、焊接速度为6.5 mm/s时,接头抗拉强度最大为1 010 MPa,达到母材强度的92.7%。高氮钢电子束焊焊缝中氮逸失较少,氮含量下降不多,由0.74%下降到0.64%。     

使用机器人焊接中厚板对接焊缝工艺参数的选择

<正>目前,使用焊接机器人进行焊接作业,可实现全自动及半自动生产,大幅度提高焊接效率,降低焊接人员劳动强度。机器人焊接工艺参数的匹配是否合理,直接影响焊缝质量。本文以使用机器人焊接中厚板的对接焊缝为例,通过焊接实验和焊缝断面形状分析,总结出了一套比较适宜的工艺参数。1.对接焊缝接头结构适用于机器人焊接的中厚板对接焊缝接头结构如下:板厚为12~18mm;两侧坡口角度相同,角     

60mm厚Q345钢板电子束焊接接头的显微组织及硬度分布

利用电子束焊接方法焊接了60mm厚Q345钢板,研究了接头焊缝区的显微组织及显微硬度分布。结果表明:电子束焊接能够一次性焊透60mm厚Q345钢板,得到成形良好且没有明显气孔、裂纹等缺陷的焊接接头,焊缝深宽比很大,约15∶1;焊缝中心顶层由先共析铁素体、侧板条铁素体和针状铁素体组成,沿着焊缝深度方向铁素体数量减少、板条状马氏体和针状铁素体数量增加且针状铁素体间距变小,晶粒尺寸减小;从焊缝顶层到底层,焊缝中心的硬度呈波动性增大趋势,焊缝区的显微硬度高于母材和热影响区的,且沿着深度方向焊缝区硬度的增长速率明显增大。     

薄板奥氏体不锈钢对接焊缝超声波探伤方法研究

通过对超声波应用于薄板奥氏体不锈钢对接焊接接头的研究和试验,开发了薄板奥氏体不锈钢对接焊接接头超声检测和质量分级方法。试块探伤试验和现场实物检测试验表明,对板厚为3～10 mm的在用压力容器奥氏体不锈钢对接焊缝及母材,辅以超声波探伤,可以及时发现奥氏体不锈钢容器在对接焊缝、封头扳边处、支座角焊缝母材等处存在的各种形式的裂纹或缺陷,有效避免出现容器的失效事故。     

高强韧中锰钢CO2气体保护焊接头的疲劳性能

采用CO₂气体保护焊对30 mm厚高强韧中锰钢板进行对焊试验,通过圆棒拉压疲劳试验获得中锰钢焊接接头的应力幅-寿命曲线,测定了其高周疲劳极限并观察其断口形貌。结果表明：在应力比为-1、循环次数为10⁷周次条件下,中锰钢焊接接头的高周疲劳极限为353 MPa;当中锰钢焊接接头焊缝中存在明显的焊接缺陷时,疲劳裂纹萌生于微观缺陷处,而当焊缝中无焊接缺陷时,疲劳裂纹萌生于试样表面熔合线位置,疲劳裂纹扩展区表面粗糙,存在着明显的二次裂纹,瞬断区表面存在大量均匀细小的韧窝。     

激光-电弧复合焊接的坡口间隙桥接能力

为推动激光-电弧复合焊接的工程应用,对其接头间隙桥接能力进行了系统研究.结果表明:激光-电弧复合焊接具有很强的间隙桥接能力,板厚4mm时最大可焊间隙量为1.8mm,板厚6mm时最大可焊间隙量为2.8mm;存在获得良好焊缝成形的接头间隙范围,板厚4mm时接头间隙范围为0.5～1mm,板厚6mm时接头间隙范围为0.6～1.2mm;电弧电流能够同时改变电弧压力、熔池重力、母材和填充材料熔化数量及坡口间隙两边熔化母材的熔合状况,是提高复合焊接可焊间隙量的关键因素;在相同焊速下,较高的电弧电流有利于厚板可焊间隙量的提高,薄板则需要相对较低的电弧电流来提高可焊间隙量.     

Study on microstructure and mechanical properties of dissimilar steel joint developed using friction stir welding

In the present study, microstructure and mechanical properties of dissimilar weld of structural steel and ferritic stainless steel (FSS) plates of thickness 3 mm were investigated. The plates were butt welded by friction stir welding and defect-free welds were produced at a traverse speed of 20 mm/min and rotational speed of 508 rpm using a tungsten carbide tool. The weld joint consisted of alternate bands of both steels resembling an onion ring pattern. In the weld joint, six distinct regions were found including both the base metals. The stir zone of structural steel revealed refined grain structure of ferrite, pearlite, and martensite whereas in ferritic stainless side, highly refined ferritic grains with grain boundary martensite was observed and also confirmed by x-ray diffraction (XRD). The hardness of the weld joint varies from 186 to 572 HV. This scatter of hardness in stir zone is due to the presence of metal from both sides. The ultimate tensile and yield strengths of the transverse weld specimens was higher than the structural steel base metal whereas lower than the ferritic stainless steel, having fracture from structural steel side.     

特厚板多层多道焊的Marc有限元模拟

厚板焊接残余应力场的影响因素众多,变化复杂,其应力分布模型的研究是此领域的难点之一,有关的试验样本尚不多见。以两块100 mm的厚板焊接为研究对象,试验模型材质为A105钢,采用埋弧焊,进行多道焊接。采用试验测量和MSC.Marc有限元模拟相结合的方法,对100 mm特厚板多层多道焊的残余应力进行对比分析研究,给出上表面横向残余应力和纵向残余应力以及厚度方向残余应力的分布曲线。有限元计算结果与试验测量结果吻合较好,证明该有限元模型的合理性。特别地,厚度方向残余应力可以通过有限元模型计算得出,解决了实际工程中厚板内部应力难得出的问题,为进一步研究特厚板焊接残余应力提供参考依据。     

激光焊接速度对热轧钢板焊缝质量的影响

测量了激光对接焊后热轧钢板正背表面焊缝宽度，分析了激光焊的焊接速度对热轧钢板焊缝成形和质量的影响。结果表明：只有采用合适的离焦量，才有可能获得较好的焊缝成形质量。在激光焊接功率6kW、离焦量－1．5mm等参数下焊接3mm厚的钢板时，激光焊接速度最佳值为3900mm／min。     

Residual stress and fracture analysis of thick plate for partial penetration multi-pass weldment

Partial penetration welding joint refers to the groove weld that applies to the one side welding which does not use steel backing and to both side welding without back gouging, that is, the partial penetration welding joint leaves an unwelded portion at the root of the welding area. In this study, we analyzed the residual stress and fracture on the thick metal plates that introduced the partial penetration welding method. According to the above-mentioned welding method, we could draw a conclusion that longitudinal stress and traverse stress occurred around the welding area are so minimal and do not affect any influence. We also performed the fracture behavior evaluation on the partial penetration multi pass welding with 25.4 mm thick plate by using the J-integral, which finally led us the conclusion that the partial penetration multi-pass welding method is more applicable and effective in handling the root face with less than 6.35 mm.     

Some investigations on microstructure and mechanical properties of submerged arc welded HSLA steel joints

This paper investigates the influence of the submerged arc welding (SAW) process parameters (welding current and welding speed) on the microstructure, hardness, and toughness of HSLA steel weld joints. Attempts have also been made to analyze the results on the basis of the heat input. The SAW process was used for the welding of 16 mm thick HSLA steel plates. The weld joints were prepared using comparatively high heat input (3.0 to 6.3 KJ/mm) by varying welding current (500–700 A) and welding speed (200–300 mm/min). Results showed that the increase in heat input coarsens the grain structure both in the weld metal and heat affected zone (HAZ). The hardness has been found to vary from the weld centre line to base metal and peak hardness was found in the HAZ. The hardness of the weld metal was largely uniform. The hardness reduced with the increase in welding current and reduction in welding speed (increasing heat input) while the toughness showed mixed trend. The increase in welding current from 500 A to 600 A at a given welding speed (200 mm/min or 300 mm/min) increased toughness and further increase in welding current up to 700 A lowered the toughness. Scanning electron microscopy of the fractured surfaces of impact test specimen was carried out to study the fracture modes. Electron probe micro analysis (EPMA) was carried out to investigate the variation in wt.% of different elements in the weld metal and HAZ.     

铝合金双面双弧同步立焊工艺特征与接头组织性能分析

采用双面双弧同步立焊工艺方法,对8 mm厚5083铝合金进行自熔试验,I形坡口一次熔透,焊缝成形美观。通过调节两侧电弧热量配比研究熔池成形规律,并从焊接接头的微观组织、力学性能分析其连接机理。研究结果表明,随着热输入的增加,双面双弧同步立焊热量加速集聚,熔深以三次幂函数的速度增大。双面双弧同步立焊接头轮廓呈“双曲线形”,而相同热输入下的单面焊接头则呈“倒马鞍形”。总热输入一定的情况下,双面双弧接头正面熔宽随能量配比系数的增大而增大,反面熔宽随能量配比系数的增大而减小,中间熔宽基本不变,熔化面积随能量配比系数的增大先增大后减小;能量配比系数一定时,随着焊速的增大,接头熔宽和熔化面积均减小。母材组织为条带状纤维织构,热影响区发生静态回复与再结晶,变形组织消失,产生新晶粒,焊缝区主要由α-Al固溶体、β相(Al8Mg5)质点和骨骼状的Mg2Si析出相组成。焊缝的抗拉强度随着能量配比系数的增大而减小,拉伸断裂形式为韧性断裂。热影响区出现软化现象,双弧交汇区硬度低于正面焊缝区。     

焊接坡口对焊接接头安定性的影响研究

结合非线性叠加法和通用有限元软件ABAQUS研究了循环热-机械载荷下对焊接接头的安定性,并比较了UV形、双U形、X形、U形、单面焊及V形等6种焊接坡口形式对焊接接头安定性的影响。结果表明,选用U形坡口(焊接厚度20 mm≤t≤60 mm)及选用双U形坡口(焊接厚度t>60 mm)连接时焊接接头的安定域较大,在循环热-机械载荷下具有更好的承载能力。此研究对厚壁压力容器及管道对焊焊接接头的设计有一定指导意义。     

Forming limit investigation of friction stir welded sheets: influence of shoulder diameter and plunge depth

The main aim of the present work is to analyze the influence of shoulder diameter and plunge depth on the formability of friction stir welded sheets. The base material used for welding and forming was AA6061-T6. Formability evaluation was performed through limiting dome height tests. The forming limit curve, FLC (only in the stretching region), thickness distribution, and strain hardening exponent of the weld region were monitored during formability studies. It is found from the work that the forming limit of friction stir welded sheets is better than unwelded sheets. In general, with an increase in shoulder diameter and plunge depth, the forming limit is found to improve considerably. With a decrease in thickness gradient severity and an increase in strain hardening exponent (n) of the weld region, the forming limit is found to increase. The increase in n value of the weld region is believed to occur because of the reduction in dislocation density. The maximum thickness difference is higher in the retreating side, rather than in the advancing side, of the weld. This is due to the differential straining and hardness levels attained by both sides during friction stir welding.     

湘钢低焊接裂纹敏感性X610CF钢性能及工程应用

研究了低焊接裂纹敏感性07MnCrMoVR钢（简称X610CF钢）的力学性能、组织结构及其工程应用。通过对40mm厚钢板进行低温（-50℃）裂纹尖端张开位移试验（CTOD）,得出其a为0.12mm;在应变量为5％的情况下KK（-50℃）最低为260J,且时效敏感系数为14．6％。通过调质处理得出,X610CF系列钢在650～680℃时回火,保温时间（min）为钢板厚度的2．5～3倍时,可以得到最佳的强韧性匹配。结果表明,该钢具有较低的应变时效敏感性、优异的焊接性能和低温韧性,并且铜板的厚度≤50mm时焊前可不预热或稍加预热而不产生焊接冷裂纹,是制造大型压力容器（特别是低温和常温球罐）、水电站压力钢管的理想用材。     

新型柔性变极性等离子弧铝合金横焊技术研究

针对中厚板铝合金横向焊接的技术需求和瓶颈问题,开展变极性等离子弧穿孔横焊技术的研究。以8 mm厚铝合金板为研究对象,进行常规变极性等离子弧穿孔横焊试验,发现横焊穿孔熔池很难建立。通过横焊穿孔熔池受力计算、熔化金属流动分析,探究问题产生的原因。推导出熔池背面小孔临界半径与表面张力、电弧力和重力之间的关系式。当受力状态满足关系式时,小孔熔池才能闭合、形成焊缝。依据上述理论,提出柔性变极性等离子弧。该电弧在保证穿孔前提下,通过降低电弧压力,增大小孔临界半径,促进了穿孔熔池的稳定建立。利用该技术实现了8 mm板厚2219铝合金的穿孔横向焊接,接头成形优良。焊前预热和表面氧化膜刮削可大幅度降低横焊接头气孔缺陷。