2020年, 第29卷, 第2期 
刊出日期:2020-06-28
  

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  • 贾金龙, 赵玥, 董明晔, 吴爱萍, 李权
    中国焊接. 2020, 29(2): 1-8. https://doi.org/10.12073/j.cw.20191101002
    摘要 ( ) PDF全文 ( )   可视化   收藏
    Wire arc additive manufacture (WAAM) is a new technique to fabricate large-scale complex aluminum alloy components. However, the performance of the parts is critically influenced by residual stresses and deformation. A sequentially thermal-mechanical coupled model of residual stress and deformation for aluminum alloy WAAM parts was established based on commercial FE software ABAQUS. The temperature field was calculated by the moving heat source (MHS) method. The temperature function was obtained according to the distribution of the peak temperature. Furthermore, the MHS method and segmented temperature function (STF) method were used to calculate the residual stress and deformation. The results show that the STF method satisfies both the efficiency and accuracy requirements. 1-segment, 3-segment, and 5-segment STF methods can shorten the time for mechanical analysis by 91%, 79%, 63%, respectively. The error of the residual stress and deformation are all less than 20%. STF method provides an effective way to predict the residual stress and deformation of large-scale WAAM parts.
  • 曾氢菲, 刘雪梅, 邱呈溶
    中国焊接. 2020, 29(2): 9-16. https://doi.org/10.12073/j.cw.20191018002
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    Precise welding of the T-joints between aircraft hyperbolic panels and stringers is required. Therefore, a method of solving inverse kinematics equations for a cooperative welding robot with multiple manipulators based on neural networks was investigated. To build an effective Denavit-Hartenberg(DH)model for this robot, sample data was obtained considering the movement ranges of the robot joints. Based on back propagation (BP) and radial basis function (RBF) neural networks, 18 joint sub-spaces were mapped to the workspaces of three manipulators. The high-dimensional and nonlinear inverse kinematics problem was transformed into a multi-input and multi-output prediction model. The results revealed that the prediction model of solving the cooperative welding robot kinematics equations was quite accurate. Moreover, compared with the BP-based model, the calculation process of the RBF-based prediction model was slower, but yielded more accurate predictions.
  • 卜凡辉, 徐连勇, 荆洪阳, 庞红宁, 韩永典, 赵雷
    中国焊接. 2020, 29(2): 17-22. https://doi.org/10.12073/j.cw.20200215002
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    Based on the SYSWELD software, a 3D finite element simulation is performed to investigate the temperature field and residual stress in the repair weld process of P92 steel plates. The results show that large tensile residual stresses are generated in the repair weld and the heat-affected zone (HAZ), which gradually decrease with distance in the surrounding base metal. With an increase of the repair length, the transverse residual stress decreases in the middle of plate surface, the HAZ and the weld metal. The longitudinal stress shows a declining trend in the weld metal with an increase of the repair length, while in the middle of plate surface and the HAZ, the longitudinal stress is only minimally affected by the repair length.
  • 叶建雄, 刘承林, 张志伟, 彭星玲
    中国焊接. 2020, 29(2): 23-29. https://doi.org/10.12073/j.cw.20200202001
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    It is hard to treat the underwater weld seam images for the reason of bad brightness, low contrast and less welding seam information, so a new enhancement algorithm is proposed here. Firstly, the high frequency component was separated by Gaussian filter from origin image, and then it is processed by improved local contrast enhancement (LCE) algorithm to enhance the edge information. Secondly, the gamma transform with adaptive parameters was used to strengthen the image brightness, furthermore, contrast limited adaptive histogram equalization (CLAHE) algorithm was applied to enhance the image contrast. Finally, the two manipulated images were integrated together to obtain the desired image. Experiments on typical images were carried out, and evaluation results showed that this designed algorithm can effectively improve image contrast, highlight welding seam information. Moreover, the image average grey value was moderate, and the information entropy and average gradient were much higher than other algorithms.
  • 段爱琴, 王振书, 彭欢, 马旭颐
    中国焊接. 2020, 29(2): 30-37. https://doi.org/10.12073/j.cw.20190909002
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    By measuring and analyzing infrared thermal image of the specimen in static load tensile test process, it was studied that the influence of the undercut defects and double-sided dressing method on the deformation behavior of the laser welded joint specimens of TC4 titanium alloy. The results showed that for the unmodified specimens, the yield phenomenon occurs first in the region of the joint, but the undercut value has an effect on the stress and strain of starting to yield phenomenon, and a great effect on the plastic deformation behavior. When the undercut is less than a certain value, the large plastic deformation occurs in the base metal region and the plasticity of the specimen is comparable to that of the base metal, but the larger undercut defect results in a concentrated plastic deformation in the joint region and rapidly failed in this region. But the double-sided dressing specimen is significantly different. The physical yield is no longer concentrated in the joint region, but at the same time occurs in the several regions including joint and the base metal. And the plastic deformation mainly occurs in the base material area, similar to that of the base material.
  • 肖珺, 温涛, 陈树君, 李锐
    中国焊接. 2020, 29(2): 38-47. https://doi.org/10.12073/j.cw.20191210002
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    Teleoperation control strategies for collaborative welding system which is targeting at giving full play to human's superiority is designed and the fitness for teleoperation welding task of which are studied. During the teleoperation welding process, 6-DOF controller's signal can be converted into welding torch's position, velocity or acceleration changing which is being controlled. For welding purposes, control strategies of four modes are designed, which are static position and posture mode, dynamic position and posture mode, velocity mode and acceleration mode. A test and analysis system for testing the tracking accuracy and reliability of control strategy based on virtual reality is developed. The tracking accuracies of the four control strategies are studied in the following tests with straight line trajectory, curve trajectory or space curve trajectory. The results show that the control strategy in dynamic position and posture mode has best stability and strong adaptability which is the most suitable for the teleoperation system.
  • 明珠, 王克鸿, 刘増, 王伟, 王有祁
    中国焊接. 2020, 29(2): 48-52. https://doi.org/10.12073/j.cw.20200221002
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    The microstructure and mechanical properties of high nitrogen steel (HNS) weld metals prepared under air- and water-cooling conditions are investigated, and the effect of the cooling rate on these properties is discussed. The results indicate that an increase in the cooling rate could significantly increase the nitrogen content in HNS weld metals, especially for weld metals with a nitrogen content of 0.85%. Moreover, increasing the cooling rate could result in an increase in the tensile strength of HNS weld metals, which is found to be strongly dependent on the nitrogen content of the HNS sample. For high nitrogen austenitic stainless steel welding wire with lower nitrogen content, increasing the cooling rate could significantly improve its tensile strength, but a higher cooling rate has no influence on weld metals with nitrogen content less than 0.58%. The tensile strength of the joint reached 850 MPa.
  • 胡志强, 赵奉超, 武兴华, 王晓宇, 廖洪彬, 秦超
    中国焊接. 2020, 29(2): 53-59. https://doi.org/10.12073/j.cw.20191218007
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    Reduced-activation ferritic/martensitic steels (RAFMs) such as CLF-1 steel, have been developed as candidate structural materials for breeding blanket in fusion reactors. Hot isostatic pressing (HIP) diffusion method is expected to provide the most promising method to solve the problem to join cooling rectangular channels with thin panels during fabrication of the first wall in breeding blankets. Mechanical and microstructural characterization of HIPed joints of CLF-1 steel with four typical surface roughness has been investigated. The results indicate that with the increase of surface roughness, the tensile properties are similar to as-received CLF-1 steel, the elongation and the area reduction decreased, the impact energy decreased sharply. The HIPed joints are very sensitive to the bonding surface states, the roughness could influence degassing, oxide and cavities formation, diffusion efficiency of bonding surface, and reduce the roughness, efficient degassing and elimination of oxide formation of the HIP joint surfaces is important to obtain a satisfactory joint.
  • 黄晓猛, 宋文杰, 齐岳峰, 柳旭, 王炜
    中国焊接. 2020, 29(2): 60-64. https://doi.org/10.12073/j.cw.20200210002
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    Two kinds of silver based medium temperature brazing filler metals (45AgCuZnSn and 60AgCuSn) were selected to braze and seal brass flange pipe and copper pipe by high frequency heating brazing. In this paper, the quality of the braze was evaluated by immersion ultrasound, and the microstructure of the brazed joint was observed by SEM and EDS. The experimental results show that the high frequency heating brazing can quickly achieve the device sealing; through the ultrasonic flaw detection image calculation, the brazed bonding rate obtained by 60AgCuSn brazing is 87%, and by 45AgCuZnSn brazing is 71%; the cross-sectional area of the brazed joint obtained by two kinds of silver based medium temperature brazing filler metals is observed, the brazed joint obtained by 45AgCuZnSn brazing has defects visual, and a large amount of Zn element gathered in the defects, there is no obvious porosity in the brazed joint by 60AgCuSn brazing, and the bonding layer is dense and coherent. Through the contrast test, the choice of 60AgCuSn alloy brazing can meet the needs of high frequency brazing of brass flange pipe and copper pipe.