scholarly journals Evolution of Welding Residual Stresses within Cladding and Substrate during Electroslag Strip Cladding

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4126
Author(s):  
Mu Qin ◽  
Guangxu Cheng ◽  
Qing Li ◽  
Jianxiao Zhang
Keyword(s):  
Residual Stress ◽  
Classical Model ◽  
Stress Gradient ◽  
Welding Process ◽  
Welding Residual Stress ◽  
Oil Refining ◽  
Substrate Thickness ◽  
Preheat Temperature ◽  
Cladding Layer ◽  
Hydrogenation Reactor

Hydrogenation reactors are important oil-refining equipment that operate in high-temperature and high-pressure hydrogen environments and are commonly composed of 2.25Cr–1Mo–0.25V steel. For a hydrogenation reactor with a plate-welding structure, the processes and effects of welding residual stress (WRS) are very complicated due to the complexity of the welding structure. These complex welding residual stress distributions affect the service life of the equipment. This study investigates the evolution of welding residual stress during weld-overlay cladding for hydrogenation reactors using the finite element method (FEM). A blind hole method is applied to verify the proposed model. Unlike the classical model, WRS distribution in a cladding/substrate system in this study was found to be divided into three regions: the cladding layer, the stress-affected layer (SAL), and the substrate in this study. The SAL is defined as region coupling affected by the stresses of the cladding layer and substrate at the same time. The evolution of residual stress in these three regions was thoroughly analyzed in three steps with respect to the plastic-strain state of the SAL. Residual stress was rapidly generated in Stage 1, reaching about −440 MPa compression stress in the SAL region at the end of this stage after 2.5 s. After cooling for 154 s, at the end of Stage 2, the WRS distribution was fundamentally shaped except for in the cladding layer. The interface between the cladding layer and substrate is the most heavily damaged region due to the severe stress gradient and drastic change in WRS during the welding process. The effects of substrate thickness and preheat temperature were evaluated. The final WRS in the cladding layer first increased with the increase in substrate thickness, and then started to decline when substrate thickness reached a large-enough value. WRS magnitudes in the substrate and SAL decreased with the increase in preheat temperature and substrate thickness. Compressive WRS in the cladding layer, on the other hand, increased with the increase in preheat temperature.

scholarly journals Study on Hydrogen Diffusion Behavior during Welding of Heavy Plate

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3887
Author(s):  
Jianguo Yang ◽  
Guohao Liu ◽  
Wenjian Zheng
Keyword(s):  
Residual Stress ◽  
Hydrogen Concentration ◽  
Hydrogen Diffusion ◽  
Stress Gradient ◽  
Welding Process ◽  
Welding Residual Stress ◽  
Diffusion Behavior ◽  
Heavy Plate ◽  
Order Of Magnitude ◽  
Stress Induced Diffusion

For the multi-layer and multi-pass welding process of the heavy plate, the hydrogen diffusion behavior was numerically simulated to study the effect of solid-state phase transition (SSPT) on the hydrogen diffusion in the thickness direction, and the influence of the residual stress-induced diffusion after SSPT. The calculation results were compared with the experimental results. The comparison shows that the distribution of hydrogen concentration in the direction of thickness was in good agreement. The position with the most severe cold cracking sensitivity was located at a 20–30 mm depth from the top surface in this article. After welding, the hydrogen concentration in this position was kept at a high level for a long time under the effect of the size-constraint effect of the heavy plate and the existence of welding residual stress gradient. In addition, the SSPT reduced the residual stress level of weld metal (WM) significantly, increased that of the heat affected zone (HAZ), and the hydrogen was redistributed under the influence of stress. In the process of phase transformation, the parameters of hydrogen diffusion property of the material changed dramatically in a short time, the hydrogen diffusion coefficient increased in order of magnitude, and the solubility decreased in order of magnitude. This directly led to the upward diffusion of hydrogen in WM, and produced a self-gathering effect. For a welded joint of heavy plate, the self-gathering effect between passes was effective in the short-range and ineffective in the long-range.

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.

Instrumented-Indentation-Technique-Based Residual Stress Characterization for Weldment of Structural Components

2006 ◽  
Author(s):  
Dongil Kwon ◽  
Jung-Suk Lee ◽  
Kwang-Ho Kim ◽  
Afshin Motarjemi ◽  
Julian Speck
Keyword(s):  
Residual Stress ◽  
Welding Process ◽  
Indentation Load ◽  
Welding Residual Stress ◽  
Hole Drilling ◽  
Structural Components ◽  
Instrumented Indentation ◽  
Indentation Technique ◽  
Safety And Reliability ◽  
Depth Curve

The weld joints in structural components have long been considered important sites for safety and reliability assessment. In particular, the residual stress in piping weldments induced by the welding process must be evaluated accurately before and during service. This study reports an indentation technique for evaluating welding residual stress nondestructively. Indentation load-depth curves were found to shift with the magnitude and direction of the residual stress. Nevertheless, contact depths in the stress-free and stressed states were constant at a specific indentation load. This means that residual stress induces additional load to keep contact depth constant at the same load. By taking these phenomena into account, welding residual stress was obtained directly from the indentation load-depth curve. In addition, the results were compared with values from the conventional hole-drilling and saw-cutting method.

Nondestructive Evaluation of Welding Residual Stress in Power Plant Facilities Using Instrumented Indentation Technique

2005 ◽  
Vol 297-300 ◽  
pp. 2122-2127 ◽  
Author(s):  
Yeol Choi ◽  
Yun Hee Lee ◽  
Jae Il Jang ◽  
Sang Ki Park ◽  
Kwang Ho Kim ◽  
...  
Keyword(s):  
Residual Stress ◽  
Power Plant ◽  
Welding Process ◽  
Indentation Load ◽  
Welding Residual Stress ◽  
Hole Drilling ◽  
Instrumented Indentation ◽  
Indentation Technique ◽  
Safety And Reliability ◽  
Depth Curve

The weld joints in power-plant pipelines have long been considered important sites for safety and reliability assessment. In particular, the residual stress in pipeline weldments induced by the welding process must be evaluated accurately before and during service. This study reports an indentation technique for evaluating welding residual stress nondestructively. Indentation load-depth curves were found to shift with the magnitude and direction of the residual stress. Nevertheless, contact depths in the stress-free and stressed states were constant at a specific indentation load. This means that residual stress induces additional load to keep contact depth constant at the same load. By taking these phenomena into account, welding residual stress was obtained directly from the indentation load-depth curve. In addition, the results were compared with values from the conventional hole-drilling and saw-cutting methods.

Temperature Field and Residual Stress Analysis of the Gear on CO2 Laser Welding Process

2011 ◽  
Vol 86 ◽  
pp. 670-673
Author(s):  
Jian Luo ◽  
Fei Li ◽  
Ke Liang Xue ◽  
De Jia Liu ◽  
Hai Wei Zhang
Keyword(s):  
Residual Stress ◽  
Temperature Field ◽  
Laser Welding ◽  
Welding Process ◽  
Welding Residual Stress ◽  
Temperature Cycle ◽  
Residual Tensile Stress ◽  
Welding Seam ◽  
Welding Temperature ◽  
Laser Welding Process

The welding technique is one of important technologies on the gear manufacturing process. The special welding temperature cycle is the basic conditions of the welding residual stress appearance in the gear. The large welding residual stress will create the large deformation after the gear welding, which will affect the gear service behavior. In this paper, the finite element method has used to simulate the gear laser welding process. The temperature field and residual stress has described. The research results show that the biggest residual compressive stress appears on the transverse direction of welding region. In the longitudinal direction, the biggest residual tensile stress appears on both sides of the welding seam line. When the laser welding power is 2.4 kW and welding speed is 20mm/s, the no apparent welding deformation’s 20CrMnSi gear can be achieved really.

scholarly journals Numerical Investigations on Residual Stress in Laser Penetration Welding Process of Ultrafine-Grained Steel

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Dezheng Liu ◽  
Yan Li ◽  
Haisheng Liu ◽  
Zhongren Wang ◽  
Yu Wang
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Cross Section ◽  
Material Flow ◽  
Welding Process ◽  
Weld Bead ◽  
Welding Residual Stress ◽  
Element Analysis ◽  
Ultrafine Grained ◽  
Solidification Cracks

Weld solidification crack prevention in the laser penetration welding process is essential for the strength of the welded component. The formation of solidification cracks can ultimately be attributed to welding residual stresses, and preventive measures should be taken during welding. In this study, the effects of residual stresses on the laser penetration welding quality of ultrafine-grained steels were investigated. A heat source model was established through the analysis of the metallography of the cross section of the heat-affected zone (HAZ) of ultrafine-grained AN420s-grade steel, and the chemical composition of the weld bead was obtained using an FLS980-stm Edinburgh fluorescence spectrometer. Furthermore, the constitutive coupling relation between the temperature and material flow stress was established based on the Gibbs function, and the welding residual stress was obtained by setting trace points in a finite element analysis (FEA) model based on experimental data of the weld bead cross section under different welding conditions. The results show that weld solidification cracks will form when the residual stresses exceed the material flow stresses in the weld bead, and the residual stresses can be decreased through a reasonable increase of the welding speed. The results indicate that the proposed criterion has high accuracy and can be used to predict the formation of weld solidification cracks in the laser penetration welding process.

The Effect of Welding Residual Stress Distribution in Thickness Direction With Thick Steel Plate to Identification of Fracture Toughness

2016 ◽  
Author(s):  
Gyubaek An ◽  
Wanchuck Woo ◽  
Jeongung Park
Keyword(s):  
Residual Stress ◽  
Crack Propagation ◽  
Steel Plate ◽  
Welding Process ◽  
Welding Residual Stress ◽  
Steel Plates ◽  
Propagation Path ◽  
Crack Propagation Path ◽  
Flux Cored Arc Welding ◽  
Thick Steel

Along with the rapid increase in the size of welding structures, the steel plate used for structure has been increased in thickness. Especially, the growing capacity of large scale ships such as container ships has led to an increase in the thickness and the strength of steel plates for shipbuilding. The toughness and the resistance to brittle fractures of the steel plate tend to decrease for thick plates, which is a result of the so-called thickness effect. Steel plates with 80mm thickness were used and two welding processes, which are flux cored arc welding (FCAW) process and electron gas welding process (EGW), were used to produce full thickness weld joints. To evaluate of brittle crack propagation path, measurement of welding residual stress in both welded joint. In this study, it was aimed to investigate the effect of welding variables on the crack arrest toughness and crack propagation path of thick steel plate welds. Quantitative analysis by temperature gradient ESSO test was conducted to clarify the effect of welding variables for flux cored arc welding (FCAW) and electro gas welding (EGW) joint of thick steel plates with the thickness of 50 and 80mm. Also, welding residual stress was measured for evaluate of welding residual stress effect in both welding process in brittle crack propagation path using neutron science analysis.

Analysis on the Welding Thermal Field and Residual Stress of Thick Plate

2015 ◽  
Vol 1095 ◽  
pp. 693-697
Author(s):  
Jiu Hong Jiang ◽  
Qiang Wang ◽  
Wen Lv
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Thick Plate ◽  
Thermal Field ◽  
Welding Process ◽  
Source Model ◽  
Simulation Software ◽  
Welding Residual Stress ◽  
Element Simulation ◽  
Thick Steel

A 60mm Q345 rigid thick plate with V groove welding connection was modeled in order to simulate the welding residual stress by finite element method. Both element birth and death technique and double ellipse heat source model were introduced to simulate the welding process. The welding thermal field and residual stress of thick steel plate were analyzed by finite element simulation software ANSYS.Then the thermal field and residual stress distribution were visually demonstrated. The result shows that the thermal field shaped like a spindle during welding period and the residual stress at the mid-section in lateral, longitudinal and thickness direction of the welding joint is lower than the stress at the surface of the welding connection.

scholarly journals Estimation formula for residual stress from the blind-hole drilling method

2018 ◽  
Vol 10 (8) ◽  
pp. 168781401878740 ◽  
Author(s):  
Chi-Liang Kung ◽  
Ah-Der Lin ◽  
Po-Wei Huang ◽  
Chao-Ming Hsu
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Welding Process ◽  
Welding Residual Stress ◽  
Hole Drilling ◽  
Parameter Group ◽  
Blind Hole ◽  
Finite Element Software ◽  
Inconel 690 ◽  
Stress Components

In this study, the accuracy of blind-hole method on weld residual stress estimation is investigated. A modified parameter group has also proposed to improve the accuracy. The thermal-elastic-plastic finite element model is employed to build up the residual stress distribution and the blind-hole process. The MSC Marc finite element software package is used to simulate the welding process and the welding residual stress and strain distributions around the weld of two inconel 690 alloy plates filled with I-52 GTAW filler. Then the process of the traditional blind hole is simulated by employing the inactive elements. The data of the residual strain variations of strain gages located around the blind hole is introduced into the blind-hole method to estimate the original residual stress components at the hole center. The effects of drilling depth, drilling size, gage radius, gage position, and the distance on the accuracy of estimated residual stress have also been studied and discussed. Based on the residual stress components simulated from the welding process, a modified stress parameter group has also been proposed to improve the accuracy of blind-hole method. Numerical results indicate that the accuracy of estimated residual stress can be improved significantly by employing the proposed blind-hole parameters.

scholarly journals Finite Element Prediction of Residual Stress Distributions in a Multipass Welded Piping Branch Junction

2006 ◽  
Author(s):  
Wei Jiang ◽  
Kadda Yahiaoui
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Welding Process ◽  
Pressure Vessels ◽  
Welding Residual Stress ◽  
Stress Distributions ◽  
Multipass Welding ◽  
Hexahedral Elements ◽  
Element Removal

Piping branch junctions and nozzle attachments to main pressure vessels are common engineering components used in the power, oil and gas, and shipbuilding industries amongst others. These components are usually fabricated by multipass welding. The latter process is known to induce residual stresses at the fabrication stage which can have severe adverse effects on the in-service behavior of such critical components. It is thus desirable if the distributions of residual stresses can be predicted well in advance of welding execution. This paper presents a comprehensive study of three dimensional residual stress distributions in a stainless steel tee branch junction during a multipass welding process. A full 3D thermo-mechanical finite element model has been developed for this purpose. A newly developed meshing technique has been used to model the complex intersection areas of the welded junction with all hexahedral elements. Element removal/reactivate technique has been employed to simulate the deposition of filler material. Material, geometry and boundary nonlinearities associated with welding were all taken into account. The analysis results are presented in the form of stress distributions circumferentially along the weldline on both run and branch pipes as well as at the run and branch cross sections. In general, this computational model is capable of predicting 3D through thickness welding residual stress, which can be valuable for structural integrity assessments of complex welded geometries.

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