TA15大厚度电子束焊接头组织及性能分析

通过对TA15大厚度钛合金材料的高压电子束焊工艺进行焊接试验,观察和分析了焊接接头的宏观组织形貌和微观组织特征,测试了接头的力学性能和接头硬度分布。结果表明:TA15大厚度钛合金高压电子束焊缝区、热影响区和母材区的微观组织差别明显;焊缝抗拉强度略高于母材,但塑性低于母材;接头焊缝区显微硬度值高于母材区。     

BT22高强钛合金电子束焊接工艺研究

为研究BT22高强合金电子束焊接工艺,分别调整电子束流、聚焦电流等工艺参数对焊缝成形进行研究,并对焊后未经热处理状态和热处理过后的金相试样进行组织观察与分析。对经过热处理的焊接试样进行了显微硬度测试和拉伸性能测试。研究表明,最佳的焊接工艺参数为高压U=-60 kV,灯丝设定I_灯=650 mA,运动速度v=3 mm/s,工作距离D=295 mm,电子束流I_b=22 mA,聚焦电流I_f=680 mA。在焊缝区和热影响区的晶粒中析出细小的α片,同一集束的α片的趋向为各向同性。α片具有强化和降低β过饱和的作用,母材的晶内α片粗大。母材的硬度值高于焊缝区域,接头平均拉伸性能为938.4 MPa。     

2024铝合金电子束焊接接头的显微组织与力学性能

采用电子束焊(EBW)对2024铝合金进行焊接,研究了接头的显微组织和力学性能。结果表明:接头焊缝显微组织呈细小的等轴晶,主要由α-Al基体相及其上分布着的θ(CuAl_2)和S(Al_2CuMg)强化相组成,热影响区为粗大的枝晶;接头的抗拉强度达到母材的80%左右,热影响区是强度最薄弱的部位;焊缝的硬度低于母材和热影响区的,且热影响区存在一定的软化现象;其拉伸断口呈典型的韧窝状断口,韧窝尺寸较小且均匀。     

电子束局部热处理对TC4钛合金焊接接头组织及力学性能的影响

电子束焊后局部热处理技术是伴随电子束焊接技术发展起来的1种新颖的加工技术，可以改善和提高电子束焊缝的组织及力学性能，避免缺陷，提高焊接质量。与整体真空退火热处理相比，电子束局部热处理后TC4钛合金接头区组织形态相同，但SEM照片显示焊缝区针状组织更加细密，焊缝区显微硬度均分布较平稳；抗拉强度得到了较大的提高，拉伸塑性降低了，但达到了母材的水平。电子束焊后局部热处理技术作为中间热处理或用于无法进行整体真空热处理的情况下，是对整体真空热处理的有益补充。     

D6A超高强钢厚壁管件的电子束焊接

对D6A超高强钢细长厚壁管件作电子束焊工艺试验 ,通过优化参数 ,采取有效的措施 ,改善焊缝成型 ,解决D6A钢焊接易产生裂纹、气孔等缺陷的问题 ;制定了合适的焊后热处理工艺 ,焊接接头综合性能优良 ,强度略高于母材 ,塑、韧性指标略低于母材     

2195-T8铝锂合金激光焊接接头的组织与性能

采用高功率CO_2激光焊机焊接3.7mm厚的2195-T8铝锂合金,研究了不同焊接工艺参数对焊缝成形质量的影响,并对优化焊接工艺条件下焊态和固溶时效态焊接接头的显微组织及力学性能进行了比较。结果表明:焊态接头焊缝区的硬度为81.81HV,比母材的下降了32.3%,接头的抗拉强度为296 MPa,比母材的下降了49%;经固溶时效处理后,焊缝的组织更加均匀,晶界及晶内析出了许多弥散且均匀分布的T_1(Al_2CuLi)强化相,焊缝硬度和接头的抗拉强度比热处理前的分别提高了25.6%和13.7%。     

6061铝合金激光填丝焊接接头的组织与力学性能

通过显微硬度计、拉伸试验机、扫描电镜和X射线衍射仪等研究了激光填丝焊接6mm厚6061铝合金接头的显微组织和力学性能。结果表明:焊缝中心区域的显微组织为等轴晶,由α-Al固溶体组成,无β(Mg_2Si)强化相析出,近熔合区的焊缝组织为柱状晶;焊接接头焊缝的硬度最低,约为73HV,母材的硬度最高,约为110HV,随着距焊缝中心距离的增大,热影响区的硬度先呈波浪式增大,在距焊缝中心2.2~3.8 mm处有所下降,此外为热影响区软化区,在距焊缝中心3.8~4.4mm处又快速增大;焊接接头的抗拉强度为234 MPa,约为母材的71%,高于熔化极惰性气体保护焊接接头的;焊接接头均在焊缝处断裂,接头与母材均为韧性断裂。     

5A06铝合金不同焊接位置焊接工艺参数研究

针对5A06铝合金缺乏全位置焊接工艺这一问题,采用三个不同的焊接位置分别设置三组不同参数对其进行焊接,研究焊接位置对工艺参数和接头性能的影响。试验结果表面,采用钨极氩弧焊（GTAW）方法焊接5A06铝合金,钨极直径2.5 mm,焊接速度50 mm/min,电弧电压16 V,平焊焊接电流100 A,气体流量10 L/min,立焊焊接电流90 A,气体流量9 L/min,横焊焊接电流90 A,气体流量9 L/min,三组参数能确保焊缝表面成型良好,无焊接缺陷产生;平焊、立焊和横焊焊接后焊缝金相组织由α(Al)固溶体、β相+不溶杂质相组成,由于热输入的影响,焊缝冷却速度慢,延长了焊缝中Al-Mg共晶形成的时间,焊缝组织呈现带状或条状,母材组织呈现等轴晶状,焊缝晶粒较母材粗大;焊接过程中5A06铝合金强化力学性能元素Mn和Mg受到高温电弧作用被烧损,因此三种焊接位置焊缝硬度均比母材低,因平焊时焊接电流比横焊和立焊大,平焊焊接区域Mn和Mg元素烧损比立焊和横焊大,平焊焊缝硬度比立焊和横焊低,由于电流差距较小,硬度差值小,为5A06铝合金焊接工艺选取提供参考。     

焊后热处理对30CrMnSiNi2A钢电子束焊接件疲劳行为的影响

电子束局部热处理是一种新型的热处理方式，探讨其对电子束焊接接头组织和疲劳性能的影响规律具有十分重要的实际意义。文中采用CT(紧凑拉伸)试样，对30CrMnSiNi2A钢电子束焊接后焊态、焊后炉内整体热处理和电子束局部热处理三种焊接接头焊缝与母材的疲劳裂纹扩展速率进行试验研究；并测定上述两个部位的门槛值。结合金相组织分析，讨论焊后热处理对接头疲劳行为的影响。试验结果表明，电子束局部热处理和整体热处理都能够在一定程度上改善焊接接头的组织和近门槛值处抗疲劳裂纹扩展的能力。由于电子束局部热处理具有方便、省时、节省能源和提高生产率的优点，因而具有较大的应用潜力和研究价值。     

不同焊接速度下2024铝合金搅拌摩擦焊接头的显微硬度与拉伸性能

对5mm厚2024铝合金板进行了不同焊接速度(20～100mm·min-1)下的搅拌摩擦焊,研究了焊接接头的显微硬度与拉伸性能。结果表明:接头在垂直于焊缝方向上的显微硬度整体呈W形分布,焊核区显微硬度高于热影响区与热机影响区的,但仍低于母材的,热影响区和热机影响区过渡位置的显微硬度最低;随焊接速度的增大,焊核区的平均显微硬度升高,焊接接头的抗拉强度和伸长率均呈先增大后略微降低的趋势;当焊接速度为80mm·min-1时,抗拉强度和伸长率均达到最大值,分别为347.2MPa和7.8%;接头在热机影响区与热影响区边界发生剪切断裂,断裂位置与显微硬度最低位置相吻合,接头的断裂方式为韧性断裂。     

Effect of post weld aging treatment on tensile properties of electron beam welded AA2219 aluminum alloy

Aluminum alloy 2219 (Al-6.5%Cu) is a favourite age hardenable alloy for aerospace applications because of its excellent welding characteristics. Though AA2219 has got an edge over its 6000 and 7000 series counterparts in terms of weldability, it also suffers from poor joint strength when welded. In this investigation an attempt has been made to improve the welded joint strength through post weld aging treatment. This paper presents the effect of post-weld aging treatment on tensile properties of electron beam welded AA2219 aluminum alloy. Square butt joints were fabricated using an electron beam welding (EBW) machine of 100 kV capacity. The joints were given post-weld artificial aging treatment. Tensile tests were carried out using 100 kN, electro-mechanical controlled universal testing machine. It is found that the post-weld aging treatment is beneficial for improving weld metal hardness and tensile properties. This is mainly due to the uniform distribution of CuAl₂ precipitates in the weld metal region in post-weld aged joints compared to as welded joints as evident from weld metal microstructure.     

Effects of temper condition and post weld heat treatment on the microstructure and mechanical properties of friction stir butt-welded AA7075 Al alloy plates

In this study, AA7075-O and AA7075-T6 Al alloy plates were friction stir butt welded using two sets of weld parameters in order to investigate the effects of temper condition prior to joining and post weld heat treatment on microstructure and mechanical properties of the joints. Another goal of the work is to determine the possibility of restoring the loss of strength in the joint area experienced in welding of this alloy in the age-hardened condition by subsequent heat treatment. The study revealed that the friction stir welding resulted in a strength undermatching when the alloy joined in T6 condition while a significant strength overmatching was obtained in the joints produced in O temper condition. The post weld heat treatment led to a significant recovery in the strength of the joints produced in T6 condition, thus a significant increase in the joint performance. On the other hand, it led to a decrease in the joint performance value of the joints produced in O temper condition although the strength was increased. Furthermore, the post weld heat treatment resulted in abnormal grain growth in the joint area the degree of which depends on weld parameters used and the prior temper condition.     

Statistical analysis to predict grain size and hardness of the weld nugget of friction-stir-welded AA6061-T6 aluminium alloy joints

AA6061 aluminum alloy has gathered wide acceptance in the fabrication of light weight structures requiring high strength-to-weight ratio and good corrosion resistance. Friction-stir welding (FSW) process is an emerging solid state joining process in which the material that is being welded does not melt and recast. This process uses a non-consumable tool to generate frictional heat in the abutting surfaces. The FSW process and tool parameters play a major role in deciding the joint strength. Joint strength is influenced by grain size and hardness of the weld nugget region. Hence, in this investigation an attempt was made to develop empirical relationships to predict grain size and hardness of weld nugget of friction-stir-welded AA6061 aluminium alloy joints. The empirical relationships are developed by response surface methodology incorporating FSW tool and process parameters. A linear regression relationship was also established between grain size and hardness of the weld nugget of FSW joints.     

METAL INERT GAS WELDING OF 2519-T87 HIGH STRENGTH ALUMINUM ALLOY

20 mm thick plates of 2519-T87 high strength aluminum alloy have been welded.The effects of the compositions of filler wires,the heat input and the compositions of shielding gas on the mechanical properties and microstructure of the welded joint have been investigated.The results indicate that finer microstructure,better mechanical properties and higher value of hardness of HAZ can be obtained by using lower heat input.The use of Ar/He mixed shielding gas has several advan- tages over pure Ar shielding gas.With the increase of the proportion of He in the mixed shielding gas, the grain size of the weld metal as well as porosity susceptibility decreases.When the volume ratio of He to Ar reaches 7:3,the porosity and the grain size of weld metal reach the minimum,and the po- rosity can be further reduced by filling some CO_2.     

材料性能对搅拌摩擦焊焊缝成形的影响

采用左螺纹圆柱搅拌头对O态和T4态2024铝合金进行搅拌摩擦焊接试验,研究了材料性能对搅拌摩擦焊焊缝成形的影响,并用软性约束分析了材料性能对焊核尺寸的影响。试验结果表明：焊缝形貌受焊核周边金属约束的影响,约束程度与材料力学性能和温度有关。O态2024铝合金对接焊时,软性约束体对塑性金属横向迁移的约束小,焊核面积和焊核宽度较T4态2024铝合金的焊核面积和焊核宽度大。两种热处理状态2024铝合金对接焊时,强度和硬度较高的T4态2024铝合金置于返回边时,在焊缝两侧、前进边的软性约束体对塑性金属的约束较返回边的软性约束体对塑性金属的约束强,焊核向返回边偏移;由于在返回边有更多的塑性金属,使其沿焊缝厚度方向向上的运动趋势增强,因此返回边的焊核高度较前进边的焊核高度高。对T4态2024铝合金进行适当的预热,会增强焊缝金属的塑化程度,使其向焊缝两侧的迁移运动趋势增强,焊核宽度及面积增大。     

国内外规范中铝合金焊缝形式对强度及疲劳的影响分析

随着铝合金材料逐步用于重大结构件,对其安全性能分析日趋重视,特别是对于焊缝部位的关键设计尤为重要.文中基于国内外主要的铝合金设计规范,对铝合金结构的对接焊缝和角焊缝两种焊缝形式的构造进行比较,并对考虑热影响区软化作用下的焊接材料及铝合金构件强度及疲劳强度进行分析对比,说明不同规范对于铝合金结构焊缝形式设计计算的要点和区...     

Research on corrosion behavior of A6N01S-T5 aluminum alloy welded joint for high-speed trains

For high speed trains, safety is of utmost importance. Salt fog corrosion, intergranular corrosion tests were employed to observe the corrosion behavior of welded joint of A6N01S-T5 aluminum alloy of high-speed trains. Tensile strength and hardness changed after corrosion was tested. The micro morphologies were observed by metalloscope and laser confocal scanning microscope (LCSM). The corrosion loss and corrosion loss ratio were also investigated. The results showed that the heat affected zone (HAZ) was the most sensitive to corrosion in welded joint in the salt fog corrosion test. The potential of the corrosion of the intermetallic compound on the surface was different from the Al matrix potential, which easily generated corrosion micro-batteries that generated the corrosion pit. The weld zone was the most sensitive to corrosion in the welded joint in the intergranular corrosion test, because much corrosion produced an intermetallic phase such as CuAl₂, MgZn₂, Mg₅Al₈, which formed the deficient Cu or Mg zone potential. The potential is low, which acted as an anode and corroded. The residual stress test on the weld of the A6N01S-T5 of the W1 of the exterior surface of roof of high speed train showed there was distributed high tensile stress and compressed stress in the weld zone, HAZ zone and matrix zone. The defects will spread under the high stress and make the corrosion become severe.     

Domex700MC低合金高强钢药芯焊丝CO2气体保护焊焊接接头的组织与性能

用药芯焊丝CO2气体保护焊焊接Domex700MC低合金高强钢,用光学显微镜、硬度计和冲击试验机等对焊接接头的显微组织和力学性能进行了分析。结果表明：焊缝金属晶粒细小且分布均匀,有较多针状铁素体,但熔合区组织比较粗大,使熔合区附近塑性降低,为焊接接头的薄弱部位;焊缝金属显微硬度较高,为315HV,而在热影响区为225HV,出现软化现象;焊接接头力学性能优良,具有较高的抗拉强度（630．94MPa）和冲击功（135．34J）。     

一种铝合金扩散焊接工艺方法研究

为了满足雷达产品构件高可靠性、高精度的工艺制造需求,文中对可热处理强化铝合金6063 铝合金的试板以及雷达产品结构相关样件开展了扩散焊接试验。焊接前对试样进行了表面清理以去除表面杂质和氧化膜等,焊接后对样件开展了尺寸检验、密封性测试、强度测试和金相检测测试,评判焊缝质量。样件加强筋处在焊接后出现了明显的变形,变形和下压量成一定比例。样件密封性满足产品要求,试板平均抗拉强度为169.3 MPa。金相检测中有局部孔洞缺陷,这和扩散时间不够充分或界面夹杂物太多导致焊接面的晶界迁移不够充分有关,因此扩散焊接中零件的表面状态和焊接工艺参数的合理选择对焊缝接头的质量至关重要。     

5052铝合金-HC420LA高强钢磁脉冲焊接接头盐雾腐蚀性能

对5052铝合金-HC420LA高强钢的磁脉冲焊接接头进行了盐雾腐蚀试验，揭示了磁脉冲焊接接头的腐蚀机理。研究结果表明，铝-钢磁脉冲焊接接头的力学性能在盐雾腐蚀环境中的退化较为明显，腐蚀首先从焊缝两侧尖端开始，当腐蚀时间达到48h时，焊接接头强度已下降为原来的20%。断口微观分析表明，钢较低的电化学电位加快了腐蚀，接头的腐蚀行为具有自催化作用。