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MAIN TOPICS，ABSTRACTS & KEY WORDS

Research progress in welding technology of Al-Li alloy

Zhou Li1,2， Li Gaohui1,Liu Chaolei1,Huang Yongxian2， Feng Jicai2

(1. Shandong Provincial Key Laboratory of Special Welding Technology, Harbin Institute of Technology at Weihai, Weihai 264209, Shandong, China; 2. State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology,Harbin 150001, China).p7-12

As a new type of low density and high properties structural material, Al-Li alloy has been applied in the fields such as aerospace and railway industry. The welding technologies of Al-Li alloy is the key to its use for components in aerospace and other industries. In recent years, the welding technologies of Al-Li alloy had been developed rapidly. The characteristics, key techniques, research situation as well as advantages and applicability of main welding methods of Al-Li alloy were summarized in the present paper. Compared with the conventional fusion welding methods, friction stir welding as a new solid state joining technology could provided more superior joint performance, which shows the potential for wide applications to welding of Al-Li alloy.

Al-Li alloy, welding technology, research progress

Research of inertial friction welded joint properties

Luo Jian,Chen Huan,Liu Shanshan

(The State Key Laboratory of Mechanical Transmission, Chongqing University , Chongqing 400044,China).p13-17

Abstract The friction welding using the energy stored in the flywheel to join parts is called inertial friction welding(IFW). In this method the flywheel was replaced by continual driving device, which makes the welding process more convenient to operate. In this paper, based on the former researches, the mechanical properties of IFW joints were summarized which include the micro-hardness, tensile strength, impact strength and some other aspects. The influence factors on joints properties were discussed emphatically. It is researched for the effects of such factors as the friction pressure, friction time, forge pressure and time during the welding which provides references for the later IFW research. Finally, the present existing problems were investigated for this kind of welding. Meanwhile future direction and the key research points were provided.

Key words： inertial friction welding, joint properties, process parameters, present status and development

Application and development status of welding technology in repairing of metal structures

Wang Hao1，Li Tianci2，Zhang Lele2

(1. CSR Qingdao Sifang Locomotive & Rolling Stock Co., Ltd., Qingdao 266111, Shandong, China; 2.School of Mechanical, Electronic and Control Engineering ,Beijing Jiaotong University, Beijing 100044,China).p18-26

Abstract Welding is one of the most important structural repairing technology in modern manufacturing industry. The development of welding repairing technology is of great significance to improve the reliability and service life of metal structure. The research progresses of brazing, laser welding, friction stir welding and other welding method applied to the metal structure repairing were analyzed, then the advantages and disadvantages of different processes as well as its application field were discussed. Factors such as welding parameters design, performance testing and process control technology that acts on the welding quality were researched, and in order to get in-depth understanding of welding phenomenon of complex physical and chemical changes in the process and give support to develop higher quality welding repairing technology, the existing methods were summarized. The detection, numerical simulation and control methods of residual stress and deformation were systematically discussed, finally the future application of welding repairing method in metal structure was prospected.

Key words： welding procedure, structural repair, welding residual stress, numerical simulation

Development and algorithm implementation of laser detection system for weld profile line

Liu Hang, Li Zhiyong, Ren Jieliang, Song Chengsheng

(Welding Research Center, School of Materials Science and Engineering, North University of China, Taiyuan 030051, China).p27-31

Abstract The weld appearance detection mainly depends on simple visual observation and measurement ,its scientific nature and accuracy are affected by inspectors subjective factors. Line laser scanning method is the application of more advanced industrial in non-contact contour detection methods. Laser scans the weld appearance and weld profile can be obtained by using laser triangulation , then the shape information of the object can be obtained. Based on the above techniques, a line laser detection system was developed to detect the weld profile, which is composed of a semiconductor laser, CMOS industrial cameras, LabVIEW virtual instrument software platform. Based on LabVIEW, the programs including image acquisition, image processing system and the weld contour calculation were developed, which can obtain more accurate weld appearance contour information.

Key words： weld profile, line laser, laser triangulation method

Flat welding process design and analysis of the welding parameters of magnetic drive pump isolation sets

Zhang Ling, Xu Chuangwen, Shi Zhicheng, Jing Hongbin, Zhang Bing

(Gansu Provincial Key Laboratory of Green Cutting Technology and Application, Lanzhou Institute of Technology, Lanzhou 730050, China).p32-35

Abstract In order to reduce the processing costs of existing magnetic drive pump isolation set and improve production efficiency, a set of welding equipment was designed, which is easy processed, and can save cost and time. The equipment has been used to study the influence of welding current, argon gas flow and tungsten electrode angle on weld formation and the related welding data were obtained in tungsten argon arc welding process of stainless steel welding. The results show that by adjusting the process parameters and the interaction between different parameters, weld formation is good at the welding current of 110 A, argon gas flow of 10 L/min, and tungsten electrode of 45°.

Key words： isolation set, argon arc welding, welding parameters, weld forming

Effect of welding heat input on structure and properties of fiber laser welded joints of 7A52 aluminum alloy

Chen Chao, Chen Furong, Zhang Huijing

(School of Materials Science and Engineering，Inner Mongolia University of Technology, Hohhot 010051,China).p35-38

Abstract 6 mm thick hot rolled 7a52 aluminum alloy was welded by using fiber laser. The microstructures and properties of welded joints were studied at the same welding heat input with different welding parameters and different welding heat input. The result shows that the microstructure of welded joint consists of larger grain with equiaxed grain in the form of “snow” shape, the grain size was increased with the increase of welding heat input. With the increase of welding heat input, the loss of Mg element and Zn element were increased gradually. At the same welding heat input, high welding speed and high welding power can relatively reduce the burning loss of Mg and Zn elements. The results of hardness test showed that the microhardness of base metal is about 110 HV and microhardness in fusion center zone is the lowest, and microhardness curve in the form of “U” shape from weld center to the parent metal. With the increase of welding heat input, the joint can obviously improve the impact toughness and tensile strength. At the same welding input, the joint at high welding speed and high welding power input has lower impact toughness and higher tensile strength , the maximum tensile strength is 341.05 MPa , accounts for about 69.8% of the base metal. The tensile fractured surface of laser welded 7A52 aluminum alloy is plastic and brittle mixed fracture.

Key words： fiber laser welding, microstructural, mechanical properties

Characteristic comparison of dual and single fiber laser beam-TIG arc hybrid welding of aluminum alloy

Huang Ruisheng, Yang Haifeng, Wang Junyu, Jing Wen

(Harbin Welding Institute, China Academy of Machinery Science and Technology, Harbin 150028, China).p39-42

Abstract The characteristics of weld seam appearance, porosity, key hole behavior and mechanical properties of welded joint were analyzed with 4 mm thick aluminum alloy welded by dual and single fiber laser beam-TIG arc hybrid welding process, respectively. The results show that, when the backside melting width is similar in laser-TIG arc hybrid welding process by using dual laser beam and single laser beam, and comparing with single beam laser-TIG arc hybrid welding method, the continuity and uniformity of backside weld seam appearance are better when the dual beam laser-TIG arc hybrid welding method was used. The porosity is reduced by more than 50%. The average surface area of key hole is larger; the coefficient of surface variation of key hole is smaller. But the tensile strength, percentage elongation of fracture, microhardness and microstructure of hybrid welded joint are similar by using dual laser beam and single laser beam.

Key words： aluminum alloy, dual laser beam, TIG arc, hybrid welding

Effective extraction of laser stripes for V-shaped groove from weld pool background based on orientation saliency

Yu Zhuohua1, Hu Yanmei1,He Yinshui2

(1. Institute of Technology, East China Jiaotong University, Nanchang 330100, China; 2.School of Resources and Environment and Chemical Engineering, Nanchang University, Nanchang 330031,China).p43-45

Abstract Seam tracking is one of key technologies in robotic automatic welding. To implement autonomous seam tracking, the key is to implement accurate extraction of laser stripes used to detect weld seam profiles in thick plate welding. According to the case where weld pools and laser stripes are simultaneously in the same frame, a method to effectively extract laser stripes was proposed based on the comprehensive orientation feature maps resulting from multi-region and multi-orientation Gabor filtering. Local-region average gray maximum method was used to remove interference, which is followed by connected domain methods to remove much small interference data. Experimental results show the effectiveness and it lays a good foundation for real-time seam tracking.

Key words： orientation saliency, V-shaped groove, laser stripe extraction, gabor filtering

Active low power laser welding of H13 hot-work die steel

Zhang Chengyu, Dai Hongbin

(School of Materials Science and Engineering, Harbin University of Science and Technology, Harbin 150040, China).p46-49

Abstract It takes too long time to repair failed mold with the traditional welding processes because the heat input is dispersed and the property of the heat affected zone is easily deteriorated. The laser welding was used to repair failed mold, which has the advantages of high degree of automation, short work time and concentrated heat input. But the cost of the equipment increases dramatically as the power increases. It can effectively reduce costs that active laser welding technology is applied to mold repairing because weld seam can get a higher depth of weld in low power. The effects of active laser welding on the microstructure and weld appearance at low power were studied by using H13 hot die steel as the experimental subject. The results show that the weld appearance of with the addition of active flux is better, the color of weld is bright and the scaly figure is clear. The active laser welding makes weld width increased by 8%, and weld penetration increased by 66%. No matter coated active flux or not, there are no cracks, porosity, inclusions or other defects in the welds. However, active laser welding can increase the size of the grain in the welds.

Key words： active flux, hot work die steel, laser welding, low power

Effect of gap on robot MAG vertical-welding process

Wang Ziran，Yang Yongbo，Bai Debin，Qin Weitao

(Harbin Welding Institute, China Academy of Machinery Science and Technology, Harbin 150028, China).p50-53

Abstract MAG vertical-welding experiments were carried out by using robot, and the effect of different gaps on robot MAG vertical-weld process was studied. It is concluded that gaps can decrease the stability of the process, the weld appearance state, and made the process harder. The weld reinforcement and the penetration also have corresponding changes through metallographic experiment.

Key words： robot, vertical welding, gap

Laser solder welding system of PCB

Yin Xia, Wang Biao

(Department of Automotive Engineering, HenanPolytechnic, Zhengzhou 450046, China).p53-55

Abstract The laser was used as heat source to weld the terminal of PCB. The automatic tin wire feeding system was mounted between the focus head of laser and PCB. Before the laser welding, the laser was used to preheat the PCB, then the tin wire was fed to the underneath of the focus head of laser. The tin wire was melted into droplet by high power laser, transferred to the PCB, and formed the tin welding spot.

Key words： PCB, laser soldering, tin wire feeding structure

Effect of polarity on welding operation performance of self-shielded flux cored wire for all-position hardfacing

Xu Libao，Zhu Houguo，Zhao Kun

(Harbin Welding Institute, China Academy of Machinery Science and Technology, Harbin 150028, China).p56-59

Abstract The effect of polarity on welding operation performance of self-shielded flux cored wire for all-position hardfacing (AP-55) was studied. The stability of welding process with different polarity was evaluated by electric parameter information, which was collected with ANALYSTOR HANNOVER, and the result showed that the arc stability of AP-55 DCEN welding is better than that of DCEP. The welding spatter of different polarity was compared according to test, and the result showed that welding spatter of AP-55 DCEN welding is less than that of DCEP, and the particles are small and easy to clean when the hardfacing wire is chosen for DCEN welding.

Key words： polarity, all-position, self-shielded flux cored, hardfacing, stability of welding process, spatter

Laser-arc hybrid welding quality monitoring system for pipeline based on infrared thermal imaging analyzed technology

Jiao Zhi1,Tan Zhaobin1,Geng Shufang1,Luo Linyi1,Liang Xing1,Zhang Yani1,Sun Pengfei2,Wang Gang2,An Jian3

(1. North China Institute of Aerospace Engineering, Langfang 065000,Hebei, China; 2.Hebei Tian Hao Rui Gong intelligent Technology Co., Ltd., Langfang 065000,Hebei, China;3. University of Electronic Science and Technology of China, Chengdu 610054, China).p60-63

Abstract In order to acquire the infrared thermal image of the weld pool, Fluke RAYPi20HTRC infrared thermal imager was used in laser-arc hybrid welding process of pipeline. The infrared thermal image was analyzed based on the temperature gradient distribution of the weld puddle. The welding quality was evaluated and the weld defects were recognized by the program. And the time-space information of welding quality was recorded in real time. Laser-arc hybrid welding process quality monitoring experiment of pipeline shows that it works in a stable operation and accurate quality evaluation and defect reorganization. It can provide the important reference for on-site welding quality monitoring and weld quality testing.

Key words： welding quality， infrared Imaging， on-site monitoring， image processing

Microstructures and properties of 310 stainless steel layer deposited on Q235 steel by CMT surfacing

Liu Yang, Liu Aiguo

(School of Materials Science and Engineering，Shenyang Ligong University，Shenyang 110159，China).p64-67

Abstract H12Cr26Ni21Si stainless steel surfacing layer was prepared on Q235 steel plate with automatic cold metal transfer (CMT) welding. The parameters were welding current of 108 A, arc voltage of 15.8 V, swing wide of 12 mm，swing speed of 23 mm/s，welding speed of 2 mm/s and overlap quantity of 7 mm. A sound and defect-free surfacing layer was obtained. The microstructures and chemical composition of the surfacing layer were analyzed. The hardness and bonding strength of the interface were tested. The results show that the microstructures of the surfacing layer consist of dendritic and equiaxed austenite and the essential elements in the surfacing layer are Ni, Cr and Fe. The hardness of the surfacing layer is higher than that of the matrix and the bonding strength of the interface is greater than 405 MPa.

Key words： surfacing, stainless steel, microstructure， properties

編輯 劉 永