scholarly journals Research Progress on Numerical Simulation of Welded Joints Microstructure

2020 ◽  
Vol 571 ◽  
pp. 012145
Author(s):  
Lan Zhan ◽  
Zhen Ma ◽  
Xin He ◽  
Bing Li
Keyword(s):  
Numerical Simulation ◽  
Welded Joints ◽  
Research Progress

Finite Element Analyses of Residual Stresses in Typical Welded Joints Used in Nuclear Power Plants and Comparisons With Experiments

2010 ◽  
Author(s):  
Dean Deng ◽  
Kazuo Ogawa ◽  
Nobuyoshi Yanagida ◽  
Koichi Saito
Keyword(s):  
Numerical Simulation ◽  
Residual Stress ◽  
Residual Stresses ◽  
Welded Joints ◽  
Nuclear Power ◽  
Power Plants ◽  
Butt Joint ◽  
Welding Residual Stress ◽  
Dissimilar Metal ◽  
Water Reactors

Recent discoveries of stress corrosion cracking (SCC) at nickel-based metals in pressurized water reactors (PWRs) and boiling water reactors (BWRs) have raised concerns about safety and integrity of plant components. It has been recognized that welding residual stress is an important factor causing the issue of SCC in a weldment. In this study, both numerical simulation technology and experimental method were employed to investigate the characteristics of welding residual stress distribution in several typical welded joints, which are used in nuclear power plants. These joints include a thick plate butt-welded Alloy 600 joint, a dissimilar metal J-groove set-in joint and a dissimilar metal girth-butt joint. First of all, numerical simulation technology was used to predict welding residual stresses in these three joints, and the influence of heat source model on welding residual stress was examined. Meanwhile, the influence of other thermal processes such as cladding, buttering and heat treatment on the final residual stresses in the dissimilar metal girth-butt joint was also clarified. Secondly, we also measured the residual stresses in three corresponding mock-ups. Finally, the comparisons of the simulation results and the measured data have shed light on how to effectively simulate welding residual stress in these typical joints.

Numerical simulation of the effect of ultrasonic impact treatment on welding residual stress

2021 ◽  
pp. 2150175
Author(s):  
Tao Mo ◽  
Jingqing Chen ◽  
Pengju Zhang ◽  
Wenqian Bai ◽  
Xiao Mu ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Residual Stress ◽  
Compressive Stress ◽  
Welded Joints ◽  
Welding Process ◽  
Residual Compressive Stress ◽  
Welding Residual Stress ◽  
304 Stainless Steel ◽  
Residual Tensile Stress ◽  
Ultrasonic Impact Treatment

Ultrasonic impact treatment (UIT) is an effective method that has been widely applied in welding structure to improve the fatigue properties of materials. It combines mechanical impact and ultrasonic vibration to produce plastic deformation on the weld joints surface, which introduces beneficial compressive residual stress distribution. To evaluate the effect of UIT technology on alleviating the residual stress of welded joints, a novel numerical analysis method based on the inherent strain theory is proposed to simulate the stress superposition of welding and subsequent UIT process of 304 stainless steel. Meanwhile, the experiment according to the process was carried out to verify the simulation of residual stress values before and after UIT. By the results, optimization of UIT application could effectively reduce the residual stress concentration after welding process. Residual tensile stress of welded joints after UIT is transformed into residual compressive stress. UIT formed a residual compressive stress layer with a thickness of about 0.13 mm on the plate. The numerical simulation results are consistent with the experimental results. The work in this paper could provide theoretical basis and technical support for the reasonable evaluation of the ultrasonic impact on residual stress elimination and mechanical properties improvement of welded joints.

scholarly journals Experimental Research and Numerical Simulation of Weld Repair with High Energy Spark Deposition Method

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 980 ◽  
Author(s):  
Yingjie Zhang ◽  
Kai Yang ◽  
Jianping Zhao
Keyword(s):  
Mechanical Properties ◽  
Numerical Simulation ◽  
Residual Stress ◽  
Heat Affected Zone ◽  
Welded Joints ◽  
High Energy ◽  
Repair Welding ◽  
Repair Processes ◽  
Repair Technology ◽  
Surface Repair

For long-serviced pressure equipment that is under severe working conditions such as a high temperature, high pressure, and corrosion, the material properties and structure will be unavoidably damaged or degraded, especially cracks and other damages at key positions such as welded joints, which seriously threaten the safe operation of the equipment. In order to promote the sustainable development of industries such as the chemical and petrochemical industries, remanufacturing technology has emerged worldwide, and various surface repair processes have also rapidly developed. As an important branch of surface repair technology, the high energy spark deposition (HESD) process is a new pulse cold welding repair technology developed from electro-spark deposition, which combines the advantages of multiple surface repair processes. The HESD process has the characteristics of a smaller heat affected zone and lower welding residual stress. It is a new type of repair method that is worthy of popularization and application. The process has been initially applied in the fields of surface modification and die steel repair. In this paper, the application of the HESD process to the repair of welded joints was introduced, the mechanical properties of the joints and the residual stress distribution after welding were analyzed, and the feasibility of HESD as a repair welding method for pressure structures was discussed. First, a numerical simulation of the temperature and stress field of HESD was proposed by using ABAQUS and the related subprograms, and the validity of the simulation results was verified by the residual stress test with the indentation strain method. Due to the precise control of the heat and pulse discharge working mode, the heat-affected zone and deformation caused by the HESD were extremely small, and the residual stress that was generated was low and only concentrated on the repair welding seam. Second, according to the numerical simulation and the test results of the mechanical properties of the welded joint, the optimal repair welding process parameters were obtained through the orthogonal experiment: peak current 45 A, pulse width 90 ms, and output voltage 10 V.

Research Progress of Simulation on the Flow Field in Anaerobic Reactor

2014 ◽  
Vol 955-959 ◽  
pp. 2098-2101
Author(s):  
Qin Zhang ◽  
Qiang Li ◽  
Jia Tang
Keyword(s):  
Fluid Dynamics ◽  
Numerical Simulation ◽  
Computational Fluid Dynamics ◽  
Wastewater Treatment ◽  
Flow Field ◽  
Treatment Effect ◽  
Dynamics Simulation ◽  
Research Progress ◽  
Computational Fluid Dynamics Simulation ◽  
Anaerobic Reactor

The flow field in anaerobic reactor is very complex, but it has been given wide attention because of its important impact to wastewater treatment effect. It is often studied by numerical simulation. The paper explored the research progress of simulation on the flow field in anaerobic reactor by the summary of development of anaerobic reactor and principle and characteristics of computational fluid dynamics simulation and introduction of study and application status on numerical simulation. And then it gave its opinion on the development of simulation on the flow field in anaerobic reactor in future.

scholarly journals Numerical simulation and experimental investigation of the damage behavior on electron beam welded joints

2011 ◽  
Vol 10 ◽  
pp. 875-880 ◽  
Author(s):  
H.Y. Tu ◽  
S. Schmauder ◽  
U. Weber ◽  
Y. Rudnik ◽  
V. Ploshikhin
Keyword(s):  
Numerical Simulation ◽  
Experimental Investigation ◽  
Electron Beam ◽  
Welded Joints ◽  
Damage Behavior

Using of Welding Virtual Numerical Simulation as the Technical Support for Industry

2016 ◽  
Vol 1138 ◽  
pp. 49-55
Author(s):  
Marek Slováček ◽  
Josef Tejc ◽  
Mojmír Vaněk
Keyword(s):  
Numerical Simulation ◽  
Numerical Simulations ◽  
Welded Joints ◽  
Welding Process ◽  
Austenitic Steels ◽  
Welding Parameters ◽  
Efficient Production ◽  
Weld Joints ◽  
Mechanical Properties Prediction

Welding as a modern, highly efficient production technology found its position in almost all industries. At the same time the demands on the quality of the welded joints have been constantly growing in all production areas. Great demand on the quality of the welded joints consequently causes more experimental or prototype – so called – validation joints that take place before the welding of final construction. These experiments, prototypes aim at – for instance – defining the appropriate welding technology, material, pre-heating, welding parameters, clamping condition and optimizing the welding process. Naturally, these experiments and prototypes make production more expensive. Numerical simulations of welding – in the area of production preparation as well as of production proper – have been frequently used recently. Numerical simulations supported by experimental measurements can simulate the actual welding process very close to reality. The new material models for hardness and mechanical properties prediction based on numerical simulation solution will be introduced.The paper covers some typical welding cases from energy industrial sector. The homogenous and heterogeneous weld joints from modern energy Cr-Mo-Ni-V steels (including modern austenitic steels) were done as prototype welding. The numerical simulation of these weld joints including post weld heat treatment process were done and welding technologies were optimised based on the numerical simulation results. The calculated hardness was compared with real measurements. During project the complete material properties which are needed for numerical simulation were measured. Simplify numerical lifetime prediction of weld joints including results from numerical welding analyse (as residual stresses and plastic deformation) were done.

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