30 August 2023, Volume 0 Issue 8
    

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    Research Paper
  • Analysis and measurement of interface temperature of TC17 linear friction welding
    Du Suigeng, Chen Hu, Hu Hongyi, Li Ju
    Welding & Joining. 2023, 0(8): 1-5. https://doi.org/10.12073/j.hj.20220414004
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The welding temperature during the linear friction welding is the key parameter to study the formation and change mechanism of joint microstructure. According to the characteristics that the temperature field of weldment (excluding flash) remains basically unchanged in the quasi stable friction stage of linear friction welding process, and the heat generated is mainly taken away by flash. The average temperature of welding interface of titanium alloy TC17 in quasi stable friction stage during friction welding is solved through theoretical analysis. The temperature changes at different positions of the welding interface during linear friction welding of TC17 titanium alloy were measured by semi natural thermocouple. The results show that the measured temperature of the welding interface at the quasi stable friction stage of TC17 under typical parameters is about 1 228 ℃, and the cooling speed to 500 ℃ after welding is about 52 ℃/s. In the quasi stable friction stage, the temperature difference between the center point and the edge point of the welding interface is no more than 10 ℃, and the heating rate and cooling rate of the center point of the interface are higher than those of the edge point. The difference between the measured value and the theoretical calculated value is not more than 10%.
  • Inertial friction welding process of 42CrMo/GH4169 dissimilar metals
    Zhang Chunbo, Yuan Mingqiang, Zhou Jun, Quan Wei, Sun Jiajia, Wu Yanquan, Wang Zhiyong
    Welding & Joining. 2023, 0(8): 6-13. https://doi.org/10.12073/j.hj.20230701001
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Inertia friction welding technology was mainly used to connect medium carbon quenched and tempered steel 42CrMo with nickel base superalloy GH4169. Microstructure and mechanical properties of welded joints under different inertia were analyzed by means of optical electron microscope, scanning electron microscope, energy spectrum analyzer, microhardness tester and electronic tensile tester. The research results showed that when inertia was 168 kg·m2, flash of 42CrMo and GH4169 inertial friction welded joints was well formed, and there was no obvious defect after flash was removed. Dynamic recrystallization occurred on both sides of weld interface, and uneven intermetallic compounds (Ni-Fe-Cr, Ni3Al) and carbide layers (NbC, TiC) with thickness of 5 μm were observed, which also resulted in microhardness peak of 691 HV1.0 at the weld interface. According to tensile property test of welded joints, fracture location of samples under 168 kg·m2 at room temperature and high temperature tensile (540 ℃) occurred on the 42CrMo base metal side. Fracture morphology observation showed typical ductile fracture, tensile strength at room temperature reached 1062.5 MPa, and tensile strength at high temperature reached 687.5 MPa, which were similar to 42CrMo base metal. This indicated that intermetallic compounds and carbide layers formed at the interface promoted metallurgical bonding of interface materials, and effectively improved mechanical properties of welded joints.
  • Robot weld type recognition based on improved grey wolf algorithm optimizing SVM
    Lü Xueqin, Long Liyuan, He Xianghuan, Xie Chengzhi, Lian Jie, Zhang Min, Fang Jian
    Welding & Joining. 2023, 0(8): 14-21,36. https://doi.org/10.12073/j.hj.20220507001
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    An image acquisition system based on binocular visual sensors for robot mobile platforms was established, and an improved grey wolf algorithm combined with a minimization parameter strategy was studied to optimize support vector machines and achieve recognition of different weld types. Firstly, introducing the theory of the best point set into the Grey Wolf algorithm to generate an initial population, reducing the number of species in the Grey Wolf population and laying the foundation for the fast and stable global search of the algorithm. Then, a nonlinear convergence factor was introduced into the classifier SVM and combined with a strategy of minimizing parameters to enhance the generalization ability of the optimal parameters. Finally, an SVM model based on the optimal parameters was used for weld seam type recognition experiments. It is proved that the improved algorithm optimized SVM model has significantly improved recognition accuracy and optimization speed compared to particle swarm optimization, genetic algorithm, cuckoo bird algorithm, and basic grey wolf algorithm.
  • Online defect monitoring of CMT additive manufacturing based on sax algorithm
    Wang Hongmin, Ye Haohuai, Song Yingying, Wang Jiansheng, Deng Fuqin, Pan Zengxi
    Welding & Joining. 2023, 0(8): 22-28,36. https://doi.org/10.12073/j.hj.20221215003
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Aiming at the defects formed in the manufacturing process of additive, it will cause irreversible influence on the workpiece. The current signal and voltage signal of CMT additive manufacturing process were analyzed, and an online monitoring method of CMT additive manufacturing defects based on time series algorithm was proposed. Different welding conditions were set, the original current and voltage signals of good group and defective group were collected, and SAX (Symbolic aggregate approximation) algorithm was used to preprocess the data. Random forest model was used to reclassify numerical data to achieve real-time monitoring effect. At the same time, in order to highlight the superiority of SAX algorithm, a comparative test group was set up, and the original current data was directly put into the random forest model for classification. The experimental results showed that the accuracy of the test set of the original current group was 80%, and that of the SAX algorithm data preprocessing group was 96%.
  • Design of precision micro-resistance seam welding power for parallel packaging of electronic devices
    Xiong Mingquan, Zhang Rui, Huang Haisong, Yang Kai
    Welding & Joining. 2023, 0(8): 29-36. https://doi.org/10.12073/j.hj.20220424001
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to meet the requirements of the miniaturization of electronic devices for the fine control of welding energy, a high-frequency inverter type micro-resistance seam welding power source was designed. The insulated gate bipolar transistor IGBT module was used to build the high-frequency inverter circuit, and the inverter frequency reached 10 kHz, shortened the energy output regulation time, improved the pulse output frequency. To improve the computing capability of the system, a fully digital control system based on dual MCU architecture was designed to achieve digital control of PWM (Pulse width modulation) and the output energy waveform. In this paper, the load characteristics of the power supply were analyzed, and a five-stage output waveform scheme was designed for the phenomena of shunt and over-melting in the welding, and the output control modes of constant current, constant voltage and constant power were proposed, and the fuzzy adaptive PID intelligent control algorithm was used to realize the stable output of multi-stage pulse energy. The results showed that the intelligent control algorithm could effectively control the welding output energy, with good stability. Through the precise control of current, time, pulse number and other parameters, accurate control of output energy and waveform could be achieved, while beautiful, dense fish scale pattern weld was obtained with no obvious defects.
  • Micro-nano-structure preparation on surface of titanium alloy based on femtosecond laser and its corrosion behavior
    Zeng Junyan, Zhuang Yuan, Yang Tao, Zhong Yuting, Yang Xiangming
    Welding & Joining. 2023, 0(8): 37-43. https://doi.org/10.12073/j.hj.20230519003
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To address corrosion failure of titanium alloys in deep submerged marine service environment, femtosecond laser etching was used to prepare corrosion-resistant super-hydrophobic micro- and nano-structure on surface of titanium alloy. Mechanism of laser etching parameters on the surface etched structure and interaction effect law of surface microstructure, hydrophobic property and salt spray corrosion behavior were investigated. The results showed that surface microstructure etched by femtosecond laser could trap air between microstructures and form an air protective film between liquid and substrate material. The support of air film structure to liquid improved hydrophobic ability of titanium alloy surface, reduced contact time and contact area between corrosive liquid and substrate metal, and further improved corrosion resistance of titanium alloy.
    • Feature Article
  • Research progress of fusion welding of 7xxx high strength aluminum alloys
    Wang Longquan, Yin Tiantian, Zhang Yan, Song Min, Zhang Jilong, Qu Chang
    Welding & Joining. 2023, 0(8): 44-54. https://doi.org/10.12073/j.hj.20230417002
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    According to research status of 7xxx high strength aluminum alloy welding, it was mainly introduced from four kinds of fusion welding process including TIG, MIG, laser welding and laser-arc hybrid welding. The problems existed in fusion welding process of 7xxx high strength aluminum alloy were described in detail from aspects of welding defects, formation of weld, softening of welded joints, fatigue property and corrosion resistance. For TIG, MIG, laser welding and laser-arc hybrid welding of 7xxx high strength aluminum alloy, welding defects and low formation quality of weld and strengthened phase dissolved in welded joints could lead to softening, poor corrosion resistance and low fatigue life of welded joints. Optimizing welding parameters, reducing welding defects and improving formation quality of weld were beneficial to improve softening, corrosion resistance and fatigue life of welded joints. Selecting appropriate welding wire (containing Ti, Zr elements and Er, Sc rare earth elements) could make weld produce precipitation strengthening, fine grain strengthening and solid solution strengthening, which could improve softening problem of welded joints. Selecting appropriate post-welding heat treatment could improve size, shape and distribution of strengthening phase, and also improve softening problem of welded joints, while it could also improve corrosion resistance of welded joints.
    • Production Theme
  • Failure mechanism for Cu-Al transition lug of electrical machinery
    Li Yan, Lai Yunting, Zhang Zhongwei, Zuo Dungui
    Welding & Joining. 2023, 0(8): 55-59. https://doi.org/10.12073/j.hj.20220513001
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Cu-Al transition lug can reduce the weight and cost of the components and give full play to the performance advantages of their materials. It is an important connecting component in the active power system and is widely used in the power system. The reasons leading to fracture for Cu-Al transition lug of electric pump after 6 years operation was analyzed by means of morphology analysis, hardness test, metallographic test, SEM and other detection means. The results show that the welding process control of the Cu-Al transition lug is poor, which is resulting in incomplete plastic deformation, copper slag inclusion, holes and other defects. The cracks were formed and further expansion during the service, which the cause of the electrochemical corrosion at the above defects.
  • Analysis and optimization of abnormal horizontal welding defects in IVOSTUD stud welding
    Sun Deneng, Mao Zhongzheng, Zhang Ming, Meng Song
    Welding & Joining. 2023, 0(8): 60-64. https://doi.org/10.12073/j.hj.20220621001
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Stud welding technology, as a special welding process method for welding studs or columnar metals to the metal surface, has a wide range of applications in the manufacturing process of automobiles. In some luxury cars, the number of studs welded by stud welding is as high as three. Four hundred. This paper studies the stud welding gun produced by IVOSTUD Company, and conducts a series of research analysis and analysis on a series of problems arising from the use of this equipment for stud welding in the body production process of Beijing Benz Automotive. The simulation test has put forward effective solutions to many problems encountered in the actual production process, and implemented it on site. After a period of verification, it has been proved to be effective. This paper is a summary and refinement of the above simulation test process and research and analysis conclusions. On the one hand, it is to share experience and technical exchanges with other peers who use this stud welding gun. On the other hand, the problem solving analysis strategy and The test method of test verification is also worthy of reference and exchange and discussion with other technical engineers related to production and manufacturing.
Quarterly Established in 1978
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ShangHai Ship and Shipping Research Institute Co,.Ltd.
ISSN 1674-5949
CN 31-2023/U
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