Calculation of the cross-sectional area of the welded joint in automatic welding and surfacing

The results are presented of the investigation of the effect of the surfacing parameters on the penetration area and the thermal efficiency in the conditions of constant heat input in automatic deposition of a bead on a thick component. Correction coefficients used to determine by calculations the penetration area using the well-known and corrected Rykalin equation for a spot constantly acting rapidly moving heat source on the surface of a thick component are derived.     

基于改进热源模型的铝合金MIG焊数值分析

采用CMOS高速摄像机检测和分析铝合金熔化极气体保护焊(MIG焊)熔滴过渡行为,确定MIG焊熔滴的过渡频率和速度.在理论分析MIG焊热源特性、热作用模式以及焊缝形貌前提下,从宏观焊接热过程出发,提出并开发了适用于MIG焊的组合体积热源分布模式,MIG焊电弧被处理描述为经典的双椭球体热源模型,熔滴能量作用模式被表示成均匀球体热源模型.同时,在均匀球体热源模型中加入了熔滴热能和动能,实现了熔滴对MIG焊熔池冲击作用的影响.基于上述热源模型,建立了铝合金MIG焊温度场有限元模型,对厚板铝合金MIG焊温度场进行了模拟.结果表明,模拟获取的焊缝熔合线走势及形貌和实际焊接结果相吻合,证明开发的热源模型能够准确描述MIG焊指状熔深特性和热传导过程.     

单一成分活性剂对铝合金作用效果的研究

活性化TIG(A-TIG)焊已成为近年来的研究热点,但主要集中在不锈钢和钛合金两种材料,在铝合金中的应用较少.针对铝合金A-TIG焊进行了初步的研究和探索,选择四种单一成分的活性剂,采用表面两侧涂敷方式,通过2A14铝合金的平板堆焊实验,研究了在相同规范下不同活性剂对焊缝熔深、焊缝成形、气孔和微观组织的影响.实验结果表...     

钛合金激光-TIG复合焊接保护状态对焊缝成形及性能影响

用激光-TIG复合热源对2.5 mm厚TA15钛合金进行对接焊试验.利用万能力学拉伸机、红外热成像仪、电子探针（EPMA）、扫描电镜（SEM）等分析手段对焊接接头进行测试分析,并与单TIG焊进行对比.分析焊接工艺参数和接头保护时间对焊接接头形貌和性能的影响.结果表明,实现2.5 mm厚钛合金全熔透焊接时,激光-TIG复合焊比单TIG焊速度更快、热输入更低,焊缝和热影响区更窄,晶粒更细;相同保护条件下,激光-TIG复合焊接头比单TIG焊接头具有更高的强度、塑性和更好的疲劳性能;激光-TIG复合焊缝冷却速率高于单TIG焊,获得良好的保护状态时所需保护时间更短.     

The influence of gradient mismatches on mechanical properties and microstructure of 2219-T6 aluminum alloy VP-TIG joints

In this paper,6 mm thick 2219-T6 aluminum alloy was joined by means of variable polarity tungsten-arc welding( VP-TIG) and the influence of gradient mismatches on VP-TIG joints is investigated. The average tensile strength of the joints reduces 32%,53% and 59%,when the mismatch of the joint was 0. 635 mm,1. 44 mm,1. 83 mm,respectively.Incomplete penetration,additional bending moment( Ma) and decrease of effective load region area are considered to explain this phenomenon. The fracture location of tensile specimens occurred at the weld zone( WZ) close to partial melt zone( PMZ),corresponding to a sharp decline of microhardness from PMZ to WZ. The original position of fracture is found at weld toe,where incomplete penetration forms due to the introduction of gradient mismatches.     

铝合金激光-小功率脉冲MIG电弧复合热源焊接特性分析

针对5A06铝合金,通过一系列对比数据综合分析了MIG焊和激光MIG复合热源焊接技术在焊缝熔深、焊缝成形、焊接速度、焊接热输入等方面的优缺点.结果表明,在MIG平均电流小于200 A的小功率脉冲MIG电弧区域内,等热输入且等焊接速度条件下,激光-MIG复合热源焊接技术与MIG相比可以提高焊缝深宽比1～2倍,增加焊缝熔深0.43～2.5倍;等热输入且等平均焊接电流条件下,与MIG相比,激光MIG复合热源焊接技术可以提高焊接速度0.6～1.5倍,增加焊缝熔深0.5～5.9倍;激光MIG复合热源焊接技术可以用高于MIG焊0.6～6.5倍的焊接速度和更小的焊接热输入获得与MIG同样的焊缝熔深;与MIG焊相比,激光MIG复合热源焊缝的铺展性更好,更适合于高速焊接;MIG复合2 kW的激光能量后会增加平均电弧电压、减小平均电流.     

SiO2增加铝合金交流A-TIG焊熔深的机理

采用单组元活性剂进行铝合金交流A-TIG(Activating flux TIG)焊时,SiO2增加熔深最明显,对其增加熔深的机理进行了研究.进行正散焦真空电子束焊试验,SiO2对焊缝成形几乎没有影响;进行系列直流正接A-TIG焊试验,研究了活性剂对电弧的影响,发现SiO2使得氧化膜厚度增加,电弧极性区收缩,弧柱区扩展,电弧电压升高;进行氦气保护交流A-TIG焊试验,发现SiO2使活性剂或金属蒸发的区域变窄且蒸发量变小,熔池表面凹陷,并且在焊接过程中SiO2涂层始终存在于熔池表面,只在熔池凹陷中央区域出现很窄的裂缝,蒸气主要集中在电弧中下部.认为电弧极性区收缩和热输入增加是SiO2增加铝合金交流A-TIG焊熔深的主要机理.     

Friction welding of Cr-Zr copper alloy

Copper and copper alloys have a higher thermal conductivity than even aluminium, itself regarded as having good heat conduction. When materials with high thermal conductivity are joined, the heat rapidly diffuses in the base metal in a way that generally results in poor weldability due to the difficulty of concentrating heat in welds. To obtain sound welds with satisfactory penetration during fusion welding of copper alloys, it is necessary to ensure high-temperature preheating and high interpass temperatures. Copper alloys are also reported to face problems such as solidification cracking and blowhole formation.¹ To solve these problems, it is necessary to perform welding at low heat input for a short time, which are conflicting requirements because of the high heat conduction.     

焊接速度对AA6082搅拌摩擦焊接头根部 缺陷及性能的影响

研究了不同焊接速度对5.1 mm厚6082-T6铝合金搅拌摩擦焊接头根部缺陷及性能的影响.采用光学显微镜观察了不同参数下接头根部缺陷形貌并对不同焊接速度下的接头进行了拉伸和弯曲试验.结果表明,随着焊接速度的不断增加,接头根部未焊透缺陷倾向变大,接头软化区部位最低硬度值逐渐增高.焊接速度由50 mm/min增大到400 mm/min时,接头抗拉强度逐渐增加.进一步增大焊接速度到600 mm/min时,由于根部未焊透缺陷的严重性变大,造成接头强度下降.在软化区是接头薄弱区的条件下,其尺寸较小的根部缺陷不影响接头抗拉强度.但是对接头的抗弯强度有显著的不利影响.     

钛合金活性剂氩弧焊研究进展(1)

钛合金氩弧焊时加卤化物等活性剂焊接(A-TIG焊)不仅气孔明显减少,而且熔深可成倍增加,焊接接头力学性能也有所改善.由于焊接热输入可大大降低,因此会改善焊接接头组织和减少应力变形.厚板焊接时可大幅度提高生产率.文中介绍了A-TIG焊活性剂及形态、活性剂对焊缝熔深/熔宽比及焊接质量的影响、深熔机理及焊缝成形问题,并对一些问题进行了评论.