• Journal of the Korean Society of Safety
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• v.19 no.4 s.68
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• pp.8-13
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• 2004

The purpose of this paper is to investigate the welding residual stress distribution according to the constraint or non-constraint welding condition with titanium commonly using power station, aircraft, and ship. The measuring method of the residual stress was applied stress release rating method with strain gages and a potable strain meter. The x direction residual stress generally showed the tensile residual stress in case of res03int welding. On the other hand, the x direction residual stress under non-restraint welding were changed tensile stress into compressive stress on 15mm away from welding bead center. Also, the y direction residual stress generally showed the tensile residual stress in case of non-restraint welding and the y direction residual stress under restraint welding were changed tensile stress into compressive stress about 60mm away from welding bead center.

• Journal of Ocean Engineering and Technology
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• v.17 no.6
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• pp.65-71
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• 2003

Since the preflex beam is fabricated through welding, the pre-compressive stresses that should occur over the concrete pier are diminished by the welding residual stresses. Therefore welding residual stresses must be relieved during the fabrication. Therefore, the analysis and examination of the accurate welding residual stress distribution characteristics are necessary. In this study, accurate distribution of welding residual stress of the preflex beam is analyzed by the finite element method, using 2 dimensional and 3 dimensional elements. Further, the thermo-mechanical behavior of the preflex beam is also studied. After the finite element analysis, real distribution of welding residual stress is measured using the sectioning method, and then is compared with the simulation results. The distribution of welding residual stress by finite analysis agreed well with the experimental results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.163-168
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• 1994

Zinc coated steel sheets have been widely used in automotive industry. High power laser welding has been used as an excellent welding means for thin sheets. The welding residual stress, which was brought in laser welding, causes making weak the mechanical strength. The purpose of this study is to get the residual stress distribution in various laser welding condition by FEM and verify the results by X-Ray diffraction. Welding residual stresses have been calculated by thermal elasto-plastic analysis using finite element method. Form the results, it can be known that the laser welding condition affects to distribution of the residual stress.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.88-93
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• 2008

Weld overlay is one of the residual stress mitigation method which arrest crack. An overlay weld sued in this manner is termed a preemptive weld overlay(PWOL). PWOL was good for distribution of residual stress of dissimilar metal weld(DMW) by previous research. Because range of overlay welding is wide relatively, residual stress distribution on PWR is affected by welding sequence. In order to examine the effect of welding sequence, PWOL was applied to a specific DMW of KORI nuclear power plant by finite element analysis method. As a result, the welding direction that from nozzle to pipe is better good for residual stress distribution on PWR.

• Nuclear Engineering and Technology
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• v.52 no.8
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• pp.1862-1870
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• 2020

The purpose of this study is to investigate the effect of welding residual stress on operating stress in designing a nuclear turbine welded rotor. A two-dimensional axisymmetric finite element model is employed to calculate the residual stress before and after post weld heat treatment (PWHT), and then the superposition of residual stress after PWHT and operating stress at normal speed and overspeed were discussed. The investigated results show that operating stress can be affected significantly by welding residual stress, and the distribution trend of superposition stress at the weld area is mainly determined by welding residual stress. The superposition of residual stress and operating stress is linear superposition, and the hoop stress distribution of superposition stress is similar with the distribution of residual stress. With the increasing overspeed, the distribution pattern of the hoop superimposed stress remains almost unchanged, while the stress level increases.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.70-75
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• 2002

It is generally applied constraint welding condition to structure manufacture in the industry field. But it is thinkable that the residual stress of the construction and specimens for experiment is different because not constraint welding but non-constraint welding are applied for experiment. To apply the constraint welding condition as the industry field and compare and evaluate the welding residual stress distribution, the TlG welding of the pure titanium was carried out under constraint and non-constraint welding conditions

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.323-328
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• 2002

Since the pre flex beam is fabricated by welding, the precompressive stresses that should occur over the concrete pier are diminished by the welding residual stresses. Therefore the welding residual stresses must be relieved during the fabrication. So the analysis and examination of the accurate welding residual stress distribution characteristic are necessary. On this study, accurate distribution of welding residual stress of preflex beam is analyzed by finite element method.

• Journal of Welding and Joining
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• v.19 no.1
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• pp.49-57
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• 2001

In this study, the residual stress fields of multi-pass welded were analyzed by FEA under various geometrical conditions. In order to estimate the effects of pipe geometries on residual stress distribution, welding processes of each model were performed under the same heat cycles. And then, the influence of cutting off the weld bead on the residual stress redistribution was also estimated. From the results, in the range of t/D=0.05, axial residual stresses on the outer surface of the welded pipe were linearly decreased with pipe diameter increase. On the other hand, hoop residual stresses were not influenced by them. And both axial and hoop residual stresses on the outer surface of the welded pipe were increased with pipe diameter increase. But, when t/D was smaller than 0.05, they were converged in the nearly same value. The maximum residual stresses were generated at around HAZ. It in therefore necessary to consider them in welding design, strength evaluation, and analysis of fracture characteristics.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.3
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• pp.68-78
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• 1998

Welding structure contains residual stress due to thermal-plastic strain during welding process, and its magnitude and distribution depend on welding conditions. Cracks initiate from various defects of the weldment, propagate and lead to final fracture, The crack initiation and propagation processes are affected by the magnitude and distribution. Therefore, the magnitude and distribution of weldment residual stress should be considered for safety design and service of welding structures. Also it is very important that more accurate assessment method of fatigue crack growth must take into account the redistributing the residual stress quantitively. because the residual stress in weldment has characteristics of its redistribution with loading magnitude, number of cycles and fatigue crack propagation. In this study fatigue crack behavior of STS-304 weldment was investigated during crack propagation into tensile residual stress region or compressive residual stress region. Crack growth rates were predicted and compared with experimental results.

• Proceedings of the KWS Conference
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• 1999.10a
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• pp.331-334
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• 1999