Microstructure and mechanical properties of laser beam welded Al–Li alloy 2060 with Al–Mg filler wire

Alloy 2060-T8 is a newly developed high-strength Al–Li alloy for applications in aircraft industry. Crack-free welds were obtained in laser beam welding with 5087 filler wire under optimized welding conditions. In this paper, fusion zone microstructure and joint mechanical properties were investigated. Microstructure typical for the weld metal consists of α-Al matrix with a few nanoscale precipitates inside and a coarse icosahedral quasicrystalline T₂ phase at the dendritic and grain boundaries. The quasicrystalline occurred normally in Al–Li–Cu alloys with higher Li contents. Our investigations show that the icosahedral quasicrystalline phase T₂ phase forms in the laser-welded Al–Li alloy 2060 with lower Li content as a result of segregation and replacement of Mg element. The joint tensile strength in as-welded condition is around 317 MPa, about 63% of that of the base metal, and fracture occurs within the fusion zone.     

工艺参数对激光清洗GFRP脱模剂层影响研究

目的 有效去除GFRP表面的脱模剂,保证对玻璃纤维损害降到最低,并提高表面粗糙度。方法 运用正交试验法,采用红外脉冲激光对玻璃纤维增强树脂基复合材料(GFRP)表面喷覆黑漆层的脱模剂层进行去除试验,研究激光的平均功率(15、20、25、30 W)、激光扫描速度(240、250、255、260 mm/s)和激光脉冲频率(70、80、90、100 kHz)对清洗后试件表面形貌和微观组织的影响规律,分别探讨不同激光参数下对GFRP材料表面粗糙度及胶接强度的影响规律。结果 在激光参数为平均功率P=25 W、激光扫描速度v=255 mm/s、激光脉冲频率f=100 kHz下,可将脱模剂有效去除,且保留了玻璃纤维的完整性,同时表面粗糙度值Sa由原来的0.684 μm增加到稳定值(4.5±0.3)μm。随着平均功率的增大,试件表面粗糙度值Sa逐渐增大,其胶接强度高于未表面处理的胶接强度。随着扫描速度的增大,试件表面粗糙度值Sa先减小、后增大。随着脉冲频率的增大,试件表面粗糙度值Sa逐渐减小。结论 最佳试验制备激光清洗工艺参数为平均功率P=25 W、激光扫描速度v=255 mm/s、激光脉冲频率f =100 kHz,在此参数下能有效去除脱模剂,玻璃纤维损害降到最低,并提高表面粗糙度,有效保证GFRP板材表面质量,同时还有利于提高复合材料之间的胶接强度。该研究结果可为航空领域复合材料脱模剂的激光清洗提供工艺参数参考。     

2219铝合金不同气氛下TIG焊焊接接头组织性能

为研究氦弧TIG焊焊缝质量,对比分析了2219铝合金氦弧TIG焊与氩弧TIG焊焊缝成形及组织性能.结果表明,在背部熔宽相同的条件下,氦弧TIG焊焊缝正面熔宽、下塌量及热影响区宽度均小于氩弧TIG焊,氦弧TIG焊与氩弧TIG焊焊缝的微观组织及第二相组织基本相似,焊缝区晶粒为等轴晶,热影响区晶粒为粗大的板条状,组织为粗大的α铝基体与金属间化合物Al₂Cu及少量的共晶组织,焊缝区的第二相组织明显多于热影响区,无法发挥弥散强化的作用.氦弧TIG焊与氩弧TIG焊焊接接头的断裂方式均为韧性断裂,抗拉强度基本保持一致,氦弧TIG焊焊接接头的断裂总延伸率高于氩弧TIG焊,维氏硬度高于氩弧TIG焊焊缝的硬度.     

Visual sensing of weld pool in variable polarity TIG welding of aluminium alloy

1 Introduction Real-time measuring of the size of welding pool is the precondition to weld shape control[1?4]. Among the researched sensing methods, the passive visual image sensing has been proved to be a feasible and promising method due to its abundan…     

Microstructural evolution and its effect on mechanical properties in different regions of 2219-C10S aluminum alloy TIG-welded joint

Microstructural evolution and its effect on mechanical properties in different regions of 2219-C10S aluminum alloy tungsten inert gas (TIG) welded joint were analyzed in detail. In weld zone (WZ), α+θ eutectic structure formed at grain boundaries with no precipitates inside the grains. In partially melted zone (PMZ), symbiotic eutectic or divorced eutectic formed at grain boundaries and needle-like θ′ phases appeared in the secondary heated zone. In over aged zone (OAZ), the coarsening and dissolution of θ′ phases occurred and most θ′ phases transformed into θ phases. In general heat affected zone (HAZ), θ′ phases coarsened. Factors such as the strengthening phases, the grain size, the Cu content in matrix and the dislocation density can affect the mechanical properties in different regions of the joint. Moreover, a model describing the relationship between mechanical properties of the material and the volume fraction of precipitates, the average diameter of precipitates and the concentration of soluble elements was proposed.     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

管道全位置激光-电弧复合焊接成形有限元研究

针对管道焊接问题,对全位置激光-电弧焊接成形规律进行研究。通过创建空间位置焊接熔池成形方程组,采用ANSYS有限元软件模拟管道全位置焊接过程中的温度分布及熔池流动,根据多场耦合法,对管道全位置焊接过程进行模拟计算。结果表明,创建的管道全位置焊接熔池成形方程组,可应用于熔池受力和熔体金属运动过程,建立的全位置焊接 ANSYS有限元模型,实现了对焊接过程的温度场和流场的耦合分析;使用多场耦合,能够得到不同阶段熔池温度场与流场的分布,能够为管道焊接提供技术支撑。     

混凝土涂层超声波测厚的不确定度评定

针对混凝土表面涂层干膜厚度难以进行无损检测的问题,采用超声波涂层测厚仪对不同强度等级的混凝土涂层干膜厚度进行了测量,并对测量结果进行了不确定度评定及合格检验.结果表明:不确定度评定能够有效地反映测量结果的可信程度,也是判别测量结果是否满足要求的主要依据;混凝土强度等级越高,混凝土涂层干膜厚度测量结果的不确定度越小,反之亦然.