MAIN TOPICS，ABSTRACTS & KEY WORDS

Crack sensitivity of circumferential weld structure for superalloy GH2132

Xing Li1, Fu Xurong1, Lü Zhen2, Chen Tongcai1，Liu Chengyi1,

(1. National Defense Key Disciplines Laboratory of Light Alloy Processing Science and Technology, Nanchang Hangkong University, Nanchang 330063, China; 2. AECC South Industry Co., Ltd., Zhuzhou 412002, Hunan, China).p1-6

The TIG welding process tests of the circumferential weld between the bearing disk and the stud made of superalloy GH2132 with different boron content were carried out. The crack rates in the weld on the surface and cross-section of the weld were measured. The mechanism of weld crack was analyzed based on the microstructure and XRD measured residual stresses. The results shown that welding crack sensitivity exists in TIG welded joints of GH2132 alloy. The cracks appear in the coarse grain zone near the fusion line of the weld, and spread to the base metal along the grain boundary, which belong to liquation crack. The crack sensitivity rises with the increase of the heat input. The content of boron in the alloy has a significant influence on the sensitivity of the liquation cracking. The higher the boron content in the alloy, the higher the crack sensitivity. The location of the crack in the circumferential weld is related to the structural characteristics of the component. If the disk has a circular hole in its center and the stud on the plane of the disk is close to the hole, the crack appears in the outer side of the circumferential weld of the stud, due to the fact that the stress of the weld outside of stud is higher than that in the weld inside of the stud during welding.

GH2132,TIG welding,circumferential weld,liquation cracking,residual stress

SAW seam tracking system based on dual structure laser sensor

Zhou Yilin, Zhang Hua, Xiao Yong, Guo Liang

(Key Laboratory of Robot & Welding Automation of Jiangxi, Nanchang University, Nanchang 330031, China).p7-11

In the shipbuilding process, SAW (submerged arc welding) is the main welding process for long plate butt joining, while the use of solo structure laser sensor will bring prepositive errors caused by rail installation. For these reasons, a new SAW seam tracking system was developed based on dual structure laser sensor. The mathematical model of dual structure laser sensor was established on the basis of structured-light imaging principle. According to the mathematical model, the position and offset of welds were obtained. In connection with the characteristics of SAW, the dual structure laser sensor and image processing algorithm of V-groove weld were developed, and experiments were performed to testify the sensor and seam tracking system. The results show that the sensor can be used to detect the position and shape of welds, and the system can meet the need of practical welding perfectly.

dual structure laser sensor,submerged arc welding,seam tracking,image processing

Research status of additional electromagnetic field assisted welding

Liu Haihua，Bai Yunlong，Zhuo Yimin ，Li Tianxu

(Advanced Mechatronics Equipment Technology Tianjin Area Laboratory， Tianjin Polytechnic University， Tianjin 300387， China).p12-18

Additional electromagnetic field assisted welding has become a new technology in recent years. It can operate on the welding process by a non-contact way. The electromagnetic force can improve the performance of the weld, the production efficiency, and the crystallization of the microstructures by influences the flow of molten pool, the arc shape and the transition behavior of molten droplet. In this paper, it was summarized that different scholars at home and abroad used different kinds of electromagnetic field to influence the fluid field of molten pool, the welding arc and the transition behavior of molten droplet, which mainly include the transverse magnetic field, the longitudinal magnetic field, and sharp angle magnetic field, and so on. But the physical process of arc deposition forming under the action of electromagnetic is extremely complex, the physics mechanisms of heat, force and electromagnetic field in the welding process have not been completely analyzed, the theoretical and numerical studies are urgently needed.

electromagnetic field assisted,welding,weld forming

Process design of aluminum alloy welding procedure

Wang Xinhong，Lu Hao，Xing Liwei，Zhang Heli

(CRRC Qingdao Sifang Co.,Ltd., Qingdao 266111,Shandong, China).p19-23

The relations of welding method, welding procedure with weld mechanical properties are lack of deep understanding. Based on experiment results, the characteristics of weld partition, weld metallurgy and mechanical properties of the joint were summarized. For weldig of aluminum alloy, welding passes sequence, preheating temperature, welding torch oscillation, groove angle, etc, are critical factors of welding procedure which have significant influence on mechanical properties of the joint. The design of whole product should be resolved to the welded joint design, being considerate to complex service loads and environment. The scientific original design of welded structure is based on the adequate experiment data of material, environment, fatigue.

aluminum alloy,welding procedure design,mechanical property

Microstructure and properties of EBW joint of hot isostatic pressing TC4 titanium alloy

Ge Yifan1,2,Lang Lihui3,Huang Ning1,2,Liu Xin1,2,Zhang Pengtian1,2

(1.Beijing Spacecrafts, Beijing 100094, China; 2. Spacecraft Welding Technology and Equipment Engineering Technology Research Center of Beijing, Beijing 100094, China; 3. Beihang University, Beijing 100191, China).p24-27

Preparation of complex thin-walled titanium alloy structure can be well solved by hot isostatic pressing technology, however, which is not suitable for the large structure products because of the cost and equipment capacity. An ideal choice of preparation of large structure is electron beam welding (EBW) according to its characteristics. 5 mm thick plates of hot isostatic pressing TC4 titanium alloy were welded by EBW, and the microstructure and properties of the welded joint were studied. The distributions of microstructures in weld zone and heat affected zone were observed, and the mechanical properties of welded joints was tested and analyzed. According to the analysis results of the hot isostatic pressing TC4 titanium alloy,α′ martensite phase formed in weld zone and heat affected zone of EBW joint, which can strengthen the weld zone and heat affected zone, and lead to the hardness and strength of welded joints are higher than that of the parent material.

titanium alloy,EBW,hot isostatic pressing,microstructure and properties

Analysis on fillet loose of stainless steel tube by high-frequency induction brazing

Ma Long1,Ni Jiaqiang1,Liu Yanmei1,Wang Dapeng1，Zhang Li2

(1.Shenyang Aircraft Corporation,Shenyang 110850,China;2.Shanyang Aerospace University,Shenyang 110136,China).p28-32

1Cr18Ni9Ti stainless steel tube and 1Cr18Ni9Ti stainless steel bends were welded by high-frequency induction brazing, and the loose defects occurs in the fillet of brazed joint after brazing. The macro morphology and microstructure of brazed joint were observed and analyzed to study the microstructure and morphology of loose by optical microscope(OM)and field emission scanning electron microscope (SEM)and energy dispersive spectrometer(EDS). The loose defects were analyzed by energy dispersive spectrometer(EDS), then the distribution regular of the defects was studied. The results show that the roots of fillet exist isometric crystal and a few scattered loose, the middle of fillet exist a lot of dendritic crystal and a few loose, the tail of fillet exist a lot of aggregate shape loose and a lot of oxide slag.

stainless steel tube,high-frequency induction brazing,fillet,loose

Fatigue analysis of B780CF steel welded joint

Jia Penggang1,2，Cheng Guangfu1,2，Gao Xiuling1,2，Li Changhong1,2

The fatigue properties of the B780CF high strength steel plate in the original state (quenched and tempered state), annealed state (annealing after tempering), and the annealing state of the welded joint (quenched and tempered plate after annealing) were tested by the lifting method under the action of tension and compression, respectively. The fatigue limit of the B780CF original state, the annealed state and the welded joint annealed under the stress ratio of -1 are 400 MPa, 415 MPa and 360 MPa, respectively. The impact toughness of B780CF welded joints decreased sharply after welding and thermal annealing, and the grains in the thick zone of the heat affected zone were seriously coarsened. The softening zone existed in the transition zone and the smectite was precipitated along the grain boundary. Scanning electron microscopy observations show that high strength steel plate and welded joint fatigue source area are located in the surface of the sample, also in the defects and the tissue microstructure of the sample.

high strength steel plate,fatigue limit,fatigue source topography

Application of TIG welding technology for Cr22 type S31803 duplex stainless steel

Sun Wantian

(SINOPEC Fifth Construction Co.,Ltd., Guangzhou 510145, China).p37-39

In order to meet the welding tasks of duplex stainless steel pipe in a petrochemical device，the TIG welding process was used. On the basis of analysis of weldability and repeated tests, the reasonable welding material, welding method，welding process parameters and operation techniques and operation focus were determined, and the physical and chemical tests of the welded joint were carried out. The results show that it is feasible to use the TIG welding procedure, the welding properties can be guaranteed. The studies can be used as a reference for welding process of the similar material.

duplex stainless steel,welding material,welding process,ferrite content

Automatic control system of semi-cycle hardfacing based on PLC for boiler superheater pipe

Kou Shu1，Wang Erming2

(1. Jiaxing Vocational and Technical College, Jiaxing 314036, Zhejiang, China; 2. Dongfang Special Steel Co., Ltd., Jiaxing 314000, Zhejiang, China).p40-43

In order to improve the automation degree of semi-cycle hardfacing of boiler superheater and achieve better results of hardfacing, automatic control system of semi-cycle hardfacing for the boiler evaporator tube was designed to replace the traditional manual repeated operation based on Mitsubishi FX series PLC system. And through the communication with welding machine, as well as coordinated action of 3 axis servo motor, the semi-cycle surfacing effect was finally achieved. The system can be used to set the parameters of the water pipe and welding through the touch screen to satisfy the semi-circle hardfacing for pipes with different diameters. According to the final test in the factory, the system not only realized the automatic control of semi-cycle hardfacing, achieved high precision, greatly improved work efficiency, reduced the labor cost, but also ensured the better welding results compared to the manual hardfacing. The system can greatly improve the degree of automation, reduce the cost, and ensure better welding effect, and eventually meet the requirements.

superheater pipe,semi-cycle hardfacing,touch screen,PLC,servo motor

Feature point extraction of weld profiles based on span segmentation of slope monotone intervals

建筑工程项目的开展是一个极其复杂的过程，它要涉及到很多单位与部门，像是：设计单位、施工单位、检测部门等等，需要建筑企业管理者进行全方面的调查与分析，做出最合理的决策。建筑工程项目开展过程中，企业管理者需要做好对建筑工程造价的成本控制，减少资金的浪费，对造价风险做好分析，确保建筑工程项目可以顺利的进行。

Yu Liang1,Tang Hua1,Wang Fang1,Lu Guiqin1,He Yinshui2

(1. Jiangxi University of Technology, Nanchang 330098,China; 2. School of Resources Environmental & Chemical Engineering, Nanchang University, Nanchang 330031, China).p44-47

Feature points of the weld profile are the guide for bead planning and seam tracking in robotic welding of thick steel plates. In this paper, the extracted weld profile of T-joints was studied, and a method to extract feature points of the weld profile of T-joints was proposed based on span segmentation of slope monotone intervals using Otsu. Firstly, slopes are calculated effectively using the preprocessed weld profile data, and followed by smooth processing. Then these intervals whose slope spans are bigger than the average one are selected. In order to determine the final slope monotone intervals from the selected ones, the slope span values are segmented by Otsu, the centers of the intervals can be deemed as the feature points of the weld profile. The advantages of the method are that it can run well without any empirical parameters and can be applied to the typical welded joints.

feature point extraction,robotic welding,slope span,weld profile

Forming process analysis of hot deformation microstructures during inertia friction welding of FGH96/GH4169 superalloy

Wang Bin1，Huang Jihua1，Zhang Tiancang2，Ji Yajuan2，He Shengchun2

(1.School of Materials Science and Engineering，University of Science and Technology Beijing，Beijing 100083，China; 2.Beijing Aeronautical Manufacturing Technology Research Institute，Beijing 100024，China).p47-50

The model of inertia friction welding of FGH96/GH4169 was established and the forming process of the deformed grains in the joint was analyzed. The results show that the friction heat leads to the formation of the plastic layer near the interface, the plastic layer flow under the stress and results in the formation of the deformed grains. Eventually the boundary of the deformed grains are broken, and the weld zone consists of refined and equiaxed grains. The plastic metals on the interface flow on radial direction and are squeezed to form the flash on the edge. The flash can take the inclusions out friction interface shows self clean effect.

superalloy，inertia friction welding，hot deformation microstructure

Comparison of properties between SA-240 304/304L steel and 304L steel

Wu Ruiping，Wang Tianxian，Wang Wenli，Tang Botao

(Qingdao LS Heavy Machinery Equipment Co.,Ltd., Qingdao 266426,Shandong, China).p51-55

The properties of double brand stainless steel SA-240 304/304L and ordinary austenitic stainless steel 304/304L were compared and analyzed, and the double brand stainless steel SA-240 304/304L has the equivalent mechanical properties to that of stainless steel 304 and the equivalent intergranular corrosion resistance to 304L stainless steel. Welding procedure test and practical welding application were compared between the double brand stainless steel SA-240 304/304L and stainless steel 304L by using electrode arc welding and tungsten argon arc welding, and the results indicate that the mechanical properties, low temperature impact toughness at -196 ℃ and the intergranular corrosion resistance of the double brand stainless steel SA-240 304/304L welded joint meet the related criteria and standard requirements.

double brand stainless steel,welding procedure,intergranular corrosion resistance

Seam tracking control system design of mobile welding robot

Li Linhui,Li Lin

(Yunnan Vocational College of Mechanical and Electrical Technology, Kunming 650203, China).p56-58，72

In order to improve the seam tracking precision of the mobile welding robot, a control system was designed based on the RBF neural network and PID control in this paper. Its structure was introduced and the corresponding dynamics model was also established. The RBF neural network structure and the design method of controller were emphatically discussed. In order to improve the control performance, the gradient information was on-line identified by neural network as well as the proportion, integral and differential coefficients can be adjusted according to the gradient information. The simulation results show that the control method can realize complex trajectory tracking. In the seam tracking process, mobile welding robots run smoothly with high tracking precision.

welding robot,seam tracking,RBF neural network,PID control

Test and application of welding robot for composite beam steel girder of HongKong-Zhuhai-Macao Bridge

Che Ping1, Li Junping1, Zou Yong2, Xue long2

(1. Research Institute of Bridge Structure, China Railway Baoji Bridge Group Co., Ltd., Baoji 721006, Shaanxi, China; 2. School of Mechanical Engineering, Opto-Mechatronic Equipment Technology Beijing Area Major Laboratory, Beijing Institute of Petro-chemical Technology, Beijing 102617, China).p59-63

In view of the bridge web welding forms, two kinds of automatic welding tests were carried out using plate of 24 mm and 40 mm. The groove types are V and X, respectively. The test weld seams were inspected that can meet the requirements of bridge steel girder web in both seam appearance and internal quality. The application of the welding robot in the butt joint of the steel girder web for the HongKong-Zhuhai-Macao Bridge shows that the welding quality and welding efficiency are obviously improved, and the welding cost is obviously reduced.

HongKong-Zhuhai-Macao Bridge,composite beam,steel girder web,welding robot,rail-type

Automatic rolling equipment of cylinder and its welding

Chai Chunhua, Chen Huanmei, Huang Zhiying

(Bayin Guoleng Vocational and Technical College, Korla 841000, Sinkiang, China).p64-67

For the welding of the cylinder in the washing tank, the automatic equipment was designed. The equipment consisted of feeding mechanism, rolling mechanism, handling equipment, clamping fixture, welding mechanism and unloading equipment. The batch feeding of plate was used, then the single plate was fed by vacuum adsorption. Through rolling mechanism, the plate was rolled to a cylinder. The fixture was used to clamp the cylinder in the horizontal and vertical direction. The rolled cylinder was welded by the argon arc welding. The testing result showed that the welds were tightness.

cylinder,rolling,welding,automation

Training and qualification of IIW international welder

Shao Hui, Qian Qiang

(Harbin Welding Training Institute, Harbin 150046, China).p68-72

The training and qualification mode and content of the international welder (IW) were introduced. There are two different ways of admission to the IW, which are namely the standard approach (admission method for full-time classes) and alternative approach. The skills and theoretical training plans as well as the assessment requirements and content of skills and theoretical certification were introduced, in which the increase in the degree of difficulty is corresponding to the difference in the welding methods and types of materials. In addition, The training process of MAG-135 international fillet welder (IFW) was introduced in detail by taking MAG-135 international fillet welder (IFW) training and qualification as an example. Finally, according to the training mode of vocational colleges in China, it was analyzed how to introduce or learn from the IW training system to improve the internationalization of the training methods of welding technology in vocational colleges in China.

international welder (IW),training and qualification,practice and promotion,comments and suggestions