2023 Vol. 38, No. 5

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Advanced welding Technology
Bypass-coupling Tripe-wire Indirect Arc Welding Process for Q345 Marine Steel with Low Energy Consumption and High Efficiency
XU Guomin, LI Boyang, HU Chenghui, LIU Liming
2023, 38(5): 1-7.
[Abstract](117) [PDF 10804KB](41)
Abstract:
Butt welding of 12 mm thick Q345 marine steel is carried out by using the bypass coupling triple-wire indirect arc (BCTW-GIA) welding and metal active gas(MAG) welding. The welding energy consumption, efficiency, mechanical properties and joint structure of the two welding processes are compared and analyzed. The results show that under the conditions of the total welding current of 420 A and welding speed of 600 mm/min, the single-pass weld with good formation is obtained by the BCTW-GIA welding, and the average tensile strength of the welded joint is 505 MPa. However, the MAG welding achieves good welding formation with a total welding current of 700 A and a three-layer and three-pass welding process, and the average tensile strength of the joint is 534 MPa. Under the experimental conditions, the welding energy consumption of the BCTW-GIA welding is only 63% of that of the MAG welding, and the welding wire deposition rate is 2.76 times of that of the MAG welding.
Study on Microstructure and Mechanical Properties of Dual Laser Symmetrical Synchronous Welded Joint of 30 mm Thick TA2
LEI Xiaowei, LIU Jia, CHEN Liyang, GAO Rui, MA Zhaowei, DU Zhibo, WANG Weichao
2023, 38(5): 8-14.
[Abstract](114) [PDF 8933KB](41)
Abstract:
In order to improve the welding efficiency and welding precision of titanium alloy, the double laser synchronous symmetric welding is carry out on the double laser synchronous symmetric welding on the 30 mm thick TA2 titanium alloy test plate, and the joint forming quality, welding deformation, microstructure, mechanical properties and process performance of the welded joint are studied. It is found out that the welded joint of the 30 mm thick TA2 plate is good and silver-white, and that the welding deformation is small. The macrostructure of the joint is of blocks, and has no obvious defects. No columnar crystals lie through the weld. The microstructures of the weld line and heat-affected zone are of the jagged α phase, and the microstructures of the base material is of the fine equiaxial α phase. The grains in the heart of the weld line are coarser than those in the near-surface of the weld line. The overall hardness of the welded joint is lower than those of the near-surface and heart of the weld line. The yield strength of the near-surface and heart of the weld line is higher than that of the base material, and the plasticity lower than that of the base material. The near-surface zone and the heart zone have a big difference in impact properties. The bending specimens are qualified, and the welded joints have good process performance. This shows that the dual laser synchronous symmetric welding technology for the thick titanium alloy plate has high-precision and good engineering application prospects.
Investigation on Corrosion Resistance of Mg-Al-Zn Alloy Joint by Laser Beam Welding
WANG Shaogang, HAN Hongli, CAO Mengyi
2023, 38(5): 15-23.
[Abstract](77) [PDF 9923KB](30)
Abstract:
The 4 mm thick Mg-Al-Zn alloy plate is welded by using laser beam welding (LBW) and laser beam welding with filler wire (LBW-F), respectively. The corrosion mechanism of the Mg-Al-Zn alloy joint is discussed. Some technical means involving polarization curve measurement, electrochemical impedance spectroscopy test, scanning electron microscopy (SEM) observation and energy dispersive spectroscopy (EDS) analysis are employed. The corrosion behavior of the LBW and LBW-F joints in the 3.5%NaCl aqueous solution is investigated, and is compared with that of the base metal (BM). Results show that the corrosion product is mainly composed of Mg(OH)2 and carbonate, and that the corrosion resistance relationship of the joints and BM can be expressed as LBW joint >LBW-F joint >BM.
Welding Simultaneous
Influence of Geometric Characteristics on Fatigue Behavior and Life Evaluation of Deep-water Platform Welding Structures
PENG Chentao, XU Lianyong, ZHAO Lei, HAN Yongdian
2023, 38(5): 24-30,43.
[Abstract](73) [PDF 10647KB](22)
Abstract:
Fatigue damage is the main cause for the structural damage of the deep-water platform. The fatigue life test of the butt and T-welded joints of the EH36 steel commonly used at sea proves that the joint form is the main reason affecting the fatigue life. Besides, the fatigue life of the welded joints has strong fatigue dispersion. With the decrease of the stress range, the fatigue life dispersion degree increases gradually. The fatigue dispersion degree of the T-welded joint is greater than that of the butt welded joint. The coupled digital image correlation(DIC) monitoring of the fatigue behaviors of the welded joints shows that the T-shaped welded joint shows greater stress concentration and stress gradient effect, and that the shape of the weld toe and stress range are the main reasons affecting the fatigue life dispersion degree of the welded joints. In the evaluation of the hot spot fatigue life, the 0.4t-1.0t extrapolation points have more accurate and effective calculation results, but the hot spot stress has to be divided according to the recommended grid size in the fatigue design.
Study on Fatigue Performance of Local Dense Weld Structures of Ship Hulls
WANG Renfu, HE Liang, SUN Lei
2023, 38(5): 31-36.
[Abstract](56) [PDF 5193KB](16)
Abstract:
To solve the fatigue problem of the dense welds of the local hull structures, by simulating the actual service environment, the engineering fatigue tests and structural stress simulation calculation are carried out on two types of local dense weld structures, and the methods to improve the fatigue performance of the dense weld structures are proposed. It is concluded that under the seawater corrosion environment, as the distance between the adjacent welds decreases, the peak stress of the structure increases, and the fatigue life of the dense weld structures decreases. When the distance between the adjacent welds is small, the surfacing and repair welding methods can effectively improve their fatigue performances.
Path Optimization of Laser Welding for Multi-Hole Tubesheet Group Seams
KANG Xuqiang, WANG Bingqi, CAO Chuchuan, HUANG Anguo
2023, 38(5): 37-43.
[Abstract](81) [PDF 5497KB](8)
Abstract:
In order to study the deformation law and control technology of the large-scale tubesheet group seam laser welding, we establish a 12 mm thick Q235 porous tubesheet group seam simulation piece considering the high temperature and mechanical performance parameters of the material, and design 5 kinds of symmetric and asymmetric welding paths. The welding process simulation software InteWeld is adopted to simulate and study the influences of different welding paths on the welding deformation. The results show that when the path is welding from top to bottom sequentially, the average and axial deformations are the smallest.
Calculation and Prediction of Structure Proportion in Heat Affected Zone of Low Alloy Steel Welding
MUREDIER Xiakeer, HUANG Anguo, KANG Xuqiang, WANG Bingqi, YU Ximing
2023, 38(5): 44-50,69.
[Abstract](85) [PDF 7803KB](15)
Abstract:
In order to obtain a welded joint with good performance, in the development environment of MATLAB App Designer, based on the CCT map of the low carbon steel alloy welding, an App that can reflect the welding process parameter, weld cooling time, and welding heat-affected zone structure and performance is developed. Four main modules of welding process parameter, welding material and CCT map, tissue ratio, metallographic diagram and hardness, and imported temperature field data are established in the App. Based on the welding CCT map, the software uses interpolation method to calculate and predict the structure ratio, metallographic map and hardness of the welding heat-affected zone. The 15MnVR steel is taken as an example for calculation and analysis.
Welding Automation and Intelligence
No-Coding Control System for Welding Robot Based on Optimized ICP Algorithm
WU Yanming, WANG Jinna, YIN Chenhao, GUO Wensong, ZOU Yirong
2023, 38(5): 51-57.
[Abstract](74) [PDF 8491KB](12)
Abstract:
With the rapid improvement of equipment and technology in the shipbuilding industry, welding robots have gradually become the main force of processing. In the face of increasing production demand, the shortcomings of insufficient intelligence and difficult operation of industrial robots are gradually exposed, which makes the transformation of enterprises into a dilemma. The development of the shipbuilding industry urgently needs intelligent and easy-to-use welding robots. In the study, we design a no-coding welding robot control system. By optimizing the iterative closest point algorithm, submillimeter-level positioning accuracy is achieved.
Low-code Visualization AI Technology Accelerating the Intelligentization of Ship Welding Process
SUN Bin, WU Yanming, YE Jun, YI Wu, ZHU Hongyan, FAN Shanshan, CHEN Jialiang
2023, 38(5): 58-69.
[Abstract](80) [PDF 12159KB](17)
Abstract:
The intelligent application research and innovation in welding quality analysis and evaluation requires industrial mechanism models and analytical methods for visualization, low-code development, and intelligent construction. The low-code visualization analysis of the welding process provides a signal analysis method based on mechanism models, which can help the shipbuilding industry solve quality problems during the welding process. This software includes analysis functions such as U-I phase diagrams, feature analysis, and short-circuit-specific analysis. Using ship engine welding as a case study, users can independently build a welding quality rating model according to the U-I phase diagrams and other functions, and achieve real-time output of on-line welding quality rating. This verifies the effectiveness of the software in welding quality analysis and evaluation, which can improve the efficiency and accuracy of the welding quality evaluation.
Comparison of Spectrometric Measurements of Plasma Temperature in Laser Penetration Welding
XIE Shun, ZHU Baoqi, ZOU Jianglin
2023, 38(5): 70-74,85.
[Abstract](43) [PDF 5367KB](9)
Abstract:
The spectrum of the CO2 laser deep penetration welding plasma and fiber laser welding plume is recorded by using a spectrometer. Both the relative intensity method and the Boltzmann plot method are used to calculate the plasma temperature. The results show that, for the same plasma, very different temperatures are figured out with relative intensity method, when different peaks are chosen. However, the calculated plasma temperatures are very similar with Boltzmann plot method when different spectrum peaks are used. Comparison of the results indicates that the measured temperature is more accurate and reliable with the Boltzmann plot method. Then Boltzmann diagram method is used to calculate the plume temperature, and it is found out that the continuous spectrum intensity of the fiber laser welding plume radiation line cannot be ignored, which is slightly different from the calculation of the plasma temperature.
Welding Quality and Relability
A Review on Integrity Evaluation and Fatigue Life Prediction Technology of Welded Joint in Ship Engineering
LIU Xuesong, GUO Shaofei
2023, 38(5): 75-85.
[Abstract](110) [PDF 10584KB](34)
Abstract:
Integrity assessment and fatigue life prediction of welded joints containing defects in hull structures are introduced, and the K criteria, COD criteria, J integral criterion, SINTAP/FITNET safety assessment method and process, and domestic and international standards for structural integrity assessment are introduced. The factors affecting the fatigue strength of welded joints, such as the average stress, residual stress and stress concentration in the joint geometry, are also analyzed. Common methods for fatigue life prediction of welded joints are introduced, such as nominal stress-based assessment methods, fracture mechanics-based assessment methods, damage mechanics-based assessment methods and other fatigue assessment methods. In addition, the functional relationship between the welded residual stress and fatigue crack extension life established based on the fracture mechanics method is introduced, which can realize the accurate prediction of fatigue life of welded structures containing residual stress.
Analysis of Stress Corrosion Cracking in Welded Joints of Q345R High-Pressure Air Cooler
WANG Yu, ZHENG Wenjian, ZHUO Min, FENG Daochen, YANG Jianguo
2023, 38(5): 86-93.
[Abstract](64) [PDF 17532KB](12)
Abstract:
A leakage failure occurred in the welded joint of the heat exchanger tube and tube plate in a high-pressure air cooler turbine. The leakage and critical positions are investigated by means of macroscopic observation, mechanical fracture and crack surface analysis, metallographic analysis, microhardness test, scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). It is found out that the cracks at the failure location expands from the welded joint of the tube box to the surface of the expansion gap, and that a large amount of S element is present at the crack surface. The failure mode is determined to be hydrogen sulfide stress corrosion cracking (SSCC) by combining stress, fracture morphology, and elemental analyse. Due to the hydrogen sulfide in the tube, and the synergistic effect of the stress concentration and structural stress by the external load, SSCC cracking occurs in the weld toe, and the cracks propagates along the fusion line to the outer wall of the expanded tube, leading to the leakage failure.
Research Progress in Improving Mechanical Properties of Welded Joints by Ultrasonic Impact Treatment
ZHOU Nanyang, HE Liang, CHENG Bin, DU Yi
2023, 38(5): 94-98.
[Abstract](89) [PDF 4121KB](18)
Abstract:
Structural failure of welded joints due to high residual stress is a common technical problem in welded structures. For ultrasonic impact treatment can effectively improve the mechanical properties of welded joints, it has been widely used in various fields. In this study, we focus on the research of ultrasonic impact technology in reducing residual stresses and improving fatigue properties of welded joints, as well as the latest related research and application of the ultrasonic impact technology with welding.
Fatigue Evaluation of Welded Joints of TA31 Titanium Alloy
CONG Rong, ZHANG Aifeng, LIU Jiande, SUN Jiangang
2023, 38(5): 99-106.
[Abstract](59) [PDF 7933KB](19)
Abstract:
Titanium alloy is a common material for deep-sea large manned carrier platform, and its fatigue properties of welded parts cannot be ignored. In this study, the butt welding and load bearing cruciform welding are carried out on the domestic TA31 titanium alloy, and the fatigue strength of the joints are evaluated by the hot spot stress approach. The test data are calculated by the method recommended by the International Institute of Welding (IIW). The S-N curves of the nominal stress and hot spot stress are obtained and compared. The influence of plate thickness on the fatigue properties of the welded joints is analyzed by the notch stress approach, and the formula of plate thickness correction is obtained. These results can provide references for fatigue evaluation and anti-fatigue design of titanium alloy structures.

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