Influences of Overall and Local PWHT on Residual Stresses in the Under-Matching Welded Joints

2015 ◽  
Author(s):  
Yuwen Qian ◽  
Jianping Zhao
Keyword(s):  
Residual Stress ◽  
Welded Joint ◽  
Welding Process ◽  
Postweld Heat Treatment ◽  
Engineering Practice ◽  
Transverse Stress ◽  
Longitudinal Stress ◽  
Finite Element Software ◽  
The Common ◽  
Postweld Heat

The under-matching welded joint is commonly used in engineering practice and the postweld heat treatment (PWHT) is the common method to reduce the residual stress in the welded joint, while the research on the under-matching welded joint after PWHT is few. The finite element software-ABAQUS is used to simulate the welding process and PWHT process of the under-matching welded joint which is the combination of CF62 (base metal) and 316L (weld) in this paper. The discussion of the influences of both overall and local PWHT on the residual stress in the under-matching welded joint is based on the experimental verification. And the influences of the two methods are compared to propose the better PWHT method to the under-matching welded joint. The results show that both overall and local PWHT can reduce the residual stress in the under-matching welded joint significantly, especially the lower transverse stress than the longitudinal stress. The distribution of the residual stress in the under-matching welded joint after the local PWHT is a little more uniform than that after the overall PWHT. The local PWHT is recommended to the under-matching welded joint in this paper.

Cause Analysis and Preventive Measures against Cracks in 15Cr1Mo1V Steel Welded Joint in Service

2017 ◽  
Vol 863 ◽  
pp. 328-333
Author(s):  
Wei Shi ◽  
Yi Shi Lv ◽  
Zhong Bing Chen ◽  
Ling Hui Meng ◽  
Li Jun Zhang ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Stress Concentration ◽  
Welded Joint ◽  
Welding Process ◽  
Postweld Heat Treatment ◽  
Additional Stress ◽  
Heat Affect Zone ◽  
Crack Morphology ◽  
Deformation Ability ◽  
Postweld Heat

Characteristics and forming causes of the cracks in welded joint of 15Cr1Mo1V steel serviced 70000h are investigated by mechanical and chemical testing and crack morphology observation. Results show that the cracks initiate from welded metal or coarse grain heat affect zone (CGHAZ) near fusion line, and there are three kinds of defects observed in the crack region, which are macrocracks, microcracks and voids. According to the forming position, process and morphology of the cracks, it is estimated that the cracks are a kind of stress relief crack (SRC). The main reasons of the cracking are because of residual stress caused by improper temperature field during post welding heat treatment, strong stress concentration caused by welding structure, additional stress caused by abnormal hangers & supports and decreased ductility of welded joint in service. The SRC in welded joint can be avoided through optimizing the welding process and postweld heat treatment(PWHT) process to ensure enough critical ductility deformation ability εc and avoiding and reducing stress concentration and additional stress to decrease ductility deformation εP of welded joint which make εc>εp consistently.

Finite Element Analysis of Effects of Preheating and Postweld Heat Treatment on Residual Stress in Pipe Welding

2011 ◽  
Vol 314-316 ◽  
pp. 428-431 ◽  
Author(s):  
Hui Du ◽  
Dong Po Wang ◽  
Chun Xiu Liu ◽  
Hai Zhang
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Finite Element ◽  
Stress Distribution ◽  
Welding Process ◽  
Postweld Heat Treatment ◽  
Element Model ◽  
Element Analysis ◽  
Pipe Welding ◽  
Postweld Heat

To simulate preheating and postweld heat treatment of Q345 steel pipe welding, the finite element model was established. The welding process was simulated by method of the ANSYS element birth and death technique. In this paper, to obtain the distribution of the temperature field and stress field in different situations, preheating processes with two different values of temperature and postweld heat treatment process were simulated respectively. The results show that preheating can homogenize residual stress distribution of the weldment and decrease the residual stress. The heat treatment reduces the residual stress in inner and outer walls by 24% and 70% respectively and the stress distribution is more even and stress concentration is reduced.

A Study of Temper Bead Technique on A508 Steel Welds

2011 ◽  
Vol 295-297 ◽  
pp. 1938-1942
Author(s):  
Wei Chih Chung ◽  
Leu Wen Tsay ◽  
Chun Chen
Keyword(s):  
Heat Treatment ◽  
Heat Affected Zone ◽  
Filler Metal ◽  
Welding Process ◽  
Postweld Heat Treatment ◽  
Weld Interface ◽  
Structural Components ◽  
Time Saving ◽  
Steel Welds ◽  
Postweld Heat

The use of temper bead technique in an attempt to eliminate the conventional postweld heat treatment (PWHT) in welding of A508 steel with Alloy 52 filler metal was evaluated. A PWHT at 621°C for 24 h reduced hardness in the heat-affected zone (HAZ) of the conventional welds but led to forming a carbon-denuded zone near the weld interface. The temper bead welding process not only softened the hardness in the HAZ but also diminished the carbon-denuded zone of A508-Alloy 52 welds. Apparently, the temper bead technique provides a convenient and time- saving process for welding/repairing large structural components.

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.

Numerical Simulation of Influences of Preheating and Postweld Heat Treatment in Welding

2012 ◽  
Vol 538-541 ◽  
pp. 1518-1521
Author(s):  
Qing Yang ◽  
Shu Jun Xie ◽  
Tian Bao Yu
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Stress Distribution ◽  
Treatment Process ◽  
Postweld Heat Treatment ◽  
Element Model ◽  
Residual Stress Field ◽  
Pipe Welding ◽  
Postweld Heat ◽  
The Finite Element Model

In this paper, to investigative effects of preheating and postweld heat treatment on residual stress field in Q345 steel pipe welding, the finite element model was established. Preheating processes and postweld heat treatment process were simulated respectively. The results show that preheating can homogenize residual stress distribution of the weldment and decrease the residual stress. The heat treatment reduces the residual stress in inner and outer walls by 40% and 60% respectively and the stress distribution is more even and the stress concentration is reduced.

Effects of Ultrasonic Impact Treatment on the Residual Stress and Microstructure of TA15 Welded Joint

2017 ◽  
Vol 898 ◽  
pp. 1056-1062 ◽  
Author(s):  
Guang Lu Qian ◽  
Xiao Yun Song ◽  
Wen Jun Ye ◽  
Rong Chen ◽  
Teng Ma ◽  
...  
Keyword(s):  
Residual Stress ◽  
Tensile Stress ◽  
Fusion Zone ◽  
Maximum Stress ◽  
Electron Beam Welding ◽  
Welded Joint ◽  
Maximum Tensile Stress ◽  
Residual Stress Distribution ◽  
Longitudinal Stress ◽  
Ultrasonic Impact Treatment

The effects of ultrasonic impact treatment (UIT) on the distribution of residual stress and on the microstructure of TA15 (Ti-6.5Al-2Zr-1Mo-1V) alloy joints by electron beam welding (EBW) were investigated. The results demonstrated that a marked microstructure change occurred after welding and the microstructure of welded joint presented a transitional change, i.e. martensite appeared in the fusion zone while equiaxed α in base mental. The residual stress in fusion zone was mainly tensile stress, and the maximum longitudinal stress value was 817MPa, which located in the centerline of welded joint. The results indicated that different impact methods have different influence on residual stress distribution. After employing UIT on welding toe, the residual stress near the welded joint exhibited a uniform distribution and the maximum tensile stress dropped to-153MPa. While after applying UIT on full coverage, the curve of the residual stress was steep and the maximum stress was still tensile stress. After UIT, no significant change occurred in microstructure and the tensile strength has a little change.

Neutron Diffraction Measurement and Numerical Simulation to Study the Effect of Repair Depth on Residual Stress in 316L Stainless Steel Repair Weld

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Wenchun Jiang ◽  
Yun Luo ◽  
BingYing Wang ◽  
Wanchuck Woo ◽  
S. T. Tu
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
316L Stainless Steel ◽  
Diffraction Measurement ◽  
Transverse Stress ◽  
Longitudinal Stress ◽  
Hardening Model ◽  
Mixed Hardening

Welding is often used to repair the defects in pressure vessels and piping, but residual stresses are generated inevitably and have a great effect on structure integrity. According to the defect size, different repair depth will be carried out, which leads to different stress state. In this paper, the effect of repair depth on residual stress in 316L stainless steel repair weld has been studied by neutron diffraction measurement and finite element modeling (FEM). The results show that the residual stresses in the deep repair are larger than those in shallow repair weld, because the deep repair involves multipass welding and brings a serious work hardening. In the weld metal, the longitudinal stress has exceeded the yield stress, and increases slightly with the increase of repair depth. In contrast to the longitudinal stress, the transverse stress is more sensitive to the repair depth. With the increase of repair depth, the transverse stress increases and even exceeds the yield strength as the repair depth is 45% of the plate thickness. At the bottom surface of the plate and heat affected zone (HAZ), both the longitudinal and transverse stresses increase as the repair depth increases. It also shows that the mixed hardening model gives the best agreement with the measurement, while isotropic and kinematic hardening models cause an overestimation and underestimation, respectively. Therefore, the mixed hardening model is recommended for the prediction of residual stresses.

Residual Stress and Bead Profile Analysis of Pulsed Nd:YAG Laser Lap Welding

2013 ◽  
Vol 284-287 ◽  
pp. 915-918
Author(s):  
Tsung Pin Hung ◽  
Chao Ming Hsu ◽  
Ah Der Lin ◽  
Jao Hwa Kuang
Keyword(s):  
Heat Transfer ◽  
Residual Stress ◽  
Nd:Yag Laser ◽  
Pulsed Laser ◽  
Welding Process ◽  
Surface Flux ◽  
Pulsed Nd:Yag Laser ◽  
Finite Element Software ◽  
Laser Lap Welding ◽  
Lap Welding

The weld bead temperature distribution and shape during pulsed Nd:YAG laser lap welding are studied. A volumetric heat source model is derived to include the surface flux and the keyhole heat transfer effects in the pulsed laser lap welding process. The proposed pulsed laser heat transfer mode is employed in a simulation with the commercial finite element software Marc. The numerically computed results of the weld pool dimensions are compared with the experimental results. The comparison shows a good agreement between the simulated and measurement results, indicating that the proposed model is feasible. The results reveal that the pulse duration and spot pitch have considerable influence on the temperature field distribution and the residual stress distribution.

Analysis of Welded Joint Under Residual Stresses

2014 ◽  
Author(s):  
H. P. Jawale ◽  
Rahul Singh
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Welded Joint ◽  
Weld Zone ◽  
Welding Process ◽  
Fatigue Behaviour ◽  
Hole Drilling ◽  
Building Structures ◽  
Residual Stress Field ◽  
Stress Relieving

Welded joint is most commonly used for building structures and machine components. Welding process involves heating followed by uneven cooling causing residual stress field. In conjunction with stresses due to external loads, in-service behaviour is affected due to residual stress in welded components. It induces defects, also alters crack initiation life, fatigue behaviour, breaking strength, corrosion resistance and increases the susceptibility of structure to failure by fracture. The residual stress is function of cooling rate and the size of weld. The role of residual stress associated with welding is therefore very important while designing mechanical parts. Conventional methods like heat treatment and shot-peening techniques becomes difficult to be applied for reduction of residual stress in general purpose applications. The work presented in this paper describes the measurement of residual stress using stress relieving method, based on hole-drilling technique. Subsequently, residual stresses are relived and measured using strain rosette near the weld zone. These strains value is converted in to stress value. Residual stress is quantified with respect to yield strength, making it possible to be considered for safe designing of weld components.

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