Effectiveness of Welding Residual Stress Reduction Method using Ultrasonic Vibration in Stainless Steel

2021 ◽  
Vol 2021.27 (0) ◽  
pp. 10B08
Author(s):  
Akira NAKAZATO ◽  
Katsumi KURITA ◽  
Shigeru AOKI ◽  
Shigeomi KOSHIMIZU ◽  
Tsuyoshi MATSUYAMA
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Ultrasonic Vibration ◽  
Stress Reduction ◽  
Reduction Method ◽  
Welding Residual Stress

Development of Stress Reduction Method in the Pipe Welded Zone by Heating

2010 ◽  
Author(s):  
Yuka Fukuda ◽  
Shinobu Okido
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Thermal Stress ◽  
Tensile Stress ◽  
Stress Reduction ◽  
Reduction Method ◽  
Residual Tensile Stress ◽  
Low Carbon ◽  
Inner Surface ◽  
Reduction Methods

Some cases of Stress Corrosion Cracking (SCC) failures in the proximity of welded zone of core internals and pipes in Primary Loop Recirculation, which are made of austenitic stainless steel, were reported in existing boiling water reactors, from the late 1970s to 1980s. As a countermeasure against SCC, low-carbon stainless steel was developed in order to reduce susceptibility to SCC, and used as standard material at that time. However, SCC failures were still observed in the core internals and pipes made of low-carbon stainless steel in recent years. It is well understood that residual tensile stress due to welding largely affects occurrence and growth of SCC in low-carbon stainless steel. Based on these observations, stress reduction methods for the pipe welded zone have already been developed such as Induction Heating Stress Improvement (IHSI) and Heat Sink Welding (HSW). However, these stress reduction methods are applied to only large-bore, thick-wall pipes, because it is difficult to apply these established countermeasures to the small-bore, thin-wall pipes which diameter is 50A and below. Thus stress reduction method for small-bore pipe has not been established. In this study, residual tensile stress reduction method that is applicable to the welded zone of small-bore pipe has been developed. The stress reduction method uses rapid quenching of inner surface of the pipe by cooling water after heating outer surface of the pipe by a heating device. Just after starting to cool the inside of the pipe, the temperature of the inner surface is low and tensile stress is generated. On the other hand, since temperature of outer surface is high, large temperature difference between inside and outside surface of the pipe develop and the high through-wall thermal stress is generated. When the temperature difference between the inner and outer surfaces of the pipe is large, thermal stress exceeds the yield stress on the pipe inner surface, and plastic deformation occurs on the inner surface of the pipe. The residual stress of the inner surface becomes compressive after the heat treatment due to the residual layer of plastic strain. In this study, the effectiveness of this method is shown by comparing the residual stress on the inner surface of the pipe before and after the application of this method by mock-up tests.

scholarly journals Evaluation of Welding Residual Stress Reduction by Ultrasonic Vibration Load

2021 ◽  
Author(s):  
Akira Nakazato ◽  
Katsumi Kurita ◽  
Shigeru Aoki ◽  
Shigeomi Koshimizu ◽  
Tsuyoshi Matuyama
Keyword(s):  
Residual Stress ◽  
Ultrasonic Vibration ◽  
Stress Reduction ◽  
Welding Residual Stress ◽  
Vibration Load

A Method of Welding Residual Stress Reduction using Ultrasonic Vibration

2021 ◽  
Vol 2021.27 (0) ◽  
pp. 10B09
Author(s):  
Takero HIROSE ◽  
Katsumi KURITA ◽  
Shigeru AOKI ◽  
Shigeomi KOSHIMIZU
Keyword(s):  
Residual Stress ◽  
Ultrasonic Vibration ◽  
Stress Reduction ◽  
Welding Residual Stress

Numerical Simulation of Residual Stress in Multi-Pass Butt-Welded Stainless Steel Pipe

2009 ◽  
Author(s):  
S. Kasa ◽  
M. Mouri ◽  
M. Tsunori ◽  
D. Takakura
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Three Dimensional ◽  
Structural Response ◽  
Welding Residual Stress ◽  
Steel Pipe ◽  
Inelastic Behavior ◽  
Axisymmetric Model ◽  
Stiffness Method ◽  
Stainless Steel Pipe

It is necessary to obtain an accurate welding residual stress distribution for the evaluation of stress corrosion cracking (SCC) behavior. However, a welding residual stress simulation for pipes is often performed by a two dimensional axisymmetric model because this type of simulation requires significant time to analyze the complicated inelastic behavior. This approximation deteriorates the modeling accuracy since the welding heat input and the structural response are approximated by axisymmetric responses although they are originally three dimensional. The authors propose “a virtual additional stiffness method” in order to improve the accuracy of the axisymmetric model. With this method, the difference between the axisymmetric model and a three dimensional behavior was greatly reduced. The virtual additional stiffness method was used to reproduce three dimensional constraints that were not taken into account in the axisymmetric model. In the case of the axisymmetric model, an unrealistic large thermal expansion was observed because of simultaneous heating along a hoop direction of the whole pipe. In order to compensate this unrealistic deformation, a virtual additional stiffness was added in axial and radial directions on the axisymmetric model. This stiffness was added by using spring elements whose positions and spring constants were determined by comparing the two and three dimensional models. Results obtained by this new method in the multi-pass butt-welded stainless steel pipe were in very good agreement with measurements of the mock-up specimens.

Development of Reduction Method for Residual Stress on Welding of Wheel Using Ultrasonic Vibration : Improvement of Transmission Device of Vibration

2004 ◽  
Vol 2004.10 (0) ◽  
pp. 461-462
Author(s):  
Shigeru Aoki ◽  
Tadshi Nishimura ◽  
Tetsumaro Hiroi ◽  
Seiji Hirai ◽  
Kunihiko Mineki
Keyword(s):  
Residual Stress ◽  
Ultrasonic Vibration ◽  
Reduction Method

The Simulation of Residual Stress for Stud Welding and Establishment of Strength Estimating Model

2008 ◽  
Vol 575-578 ◽  
pp. 816-820 ◽  
Author(s):  
Guang Tao Zhou ◽  
Xue Song Liu ◽  
Guo Li Liang ◽  
Pei Zhi Liu ◽  
De Jun Yan ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Tensile Stress ◽  
Welded Joints ◽  
Welding Residual Stress ◽  
Yield Limit ◽  
Stud Welding ◽  
Welding Joints ◽  
Simulation Results ◽  
Steel Stud

The distribution and value of welding residual stress for 1Cr18Ni9 stainless steel stud welding joints was systemically simulated by ANSYS FE software. The mathematical estimating models of strength of the welded joints were established. Simulation results showed that the welding residual stress was tensile at the edge of the stud, while it was compressive stress at the position near axis center. The largest tensile stress did not exceed yield limit of material. The residual stress had more influence on the strength of welded joints.

Validation of Welding Residual Stress Model Using Results From a Pressurizer Surge Nozzle Mockup

2011 ◽  
Author(s):  
Doug Killian
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Residual Stresses ◽  
Crack Growth ◽  
Material Properties ◽  
Welding Residual Stress ◽  
Stress Model ◽  
Dissimilar Metal ◽  
Dissimilar Metal Weld ◽  
Metal Weld

Although numerical welding simulation is now commonly used in the nuclear industry to predict residual stresses in reactor vessels and associated piping components, there are currently no universally accepted guidelines for performing such analysis. Moreover, due to the complexity of the calculations and varying analytical procedures among analysts, there remains a need to validate predictions of residual stress against benchmark studies. As part of an industry initiative to manage the degradation of dissimilar metal welds in pressurized water reactor piping that are susceptible to primary water stress corrosion cracking, the U.S Nuclear Regulatory Commission embarked on a multi-phased program to validate welding residual stress models. The aim of Phase II of this program is to obtain measured residual stresses from a pressurizer surge nozzle dissimilar metal weld mockup for use in comparisons with numerically predicted stresses. This paper presents results of finite element analysis for various stages during the fabrication of a 14–inch pressurizer surge nozzle mockup, including an Alloy 82 dissimilar metal weld between a stainless steel safe end and carbon steel nozzle, an inside surface weld repair (back weld) and fill-in weld (weld build-up), and a stainless steel “field” weld attaching a section of straight pipe to the safe end. The NRC validation program was structured to allow participants to first calculate results using their own material properties, and then tune their welding simulations to thermocouple data. This was followed by reanalysis using NRC-supplied material properties. The program was conducted as a round robin analysis among an international group of participants and formatted as a blind validation project wherein results were submitted to the NRC prior to receipt of thermocouple and material property data. Results were obtained for both kinematic and isotropic hardening rules to study the effect of these two extreme measures of material characterization on the development of residual stress. Predicted stresses are then compared to measured stress data obtained by the deep-hole drilling technique at multiple locations through the thickness of the weld. The NRC residual stress model validation project serves as a valuable contribution to the understanding of how residual stresses are developed in dissimilar metal welds. The correlation of calculated residual stresses with measured data from a relevant mockup also serves to increase confidence in predicting crack growth in these primary pressure boundary welds by removing much of the uncertainty previously associated with residual stress input to crack growth analysis.

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