scholarly journals Effect of Residual Stress on Crack Development in Longitudinal Welded Joints of a Gas Pipeline

2020 ◽  
Vol 30 ◽  
pp. 28-32
Author(s):  
Nikolay I. Golikov
Keyword(s):  
Residual Stress ◽  
Welded Joints ◽  
Gas Pipeline ◽  
Crack Development

Расчетные методы оценки ударной вязкости сварных элементов с трещинами

2020 ◽  
Vol 44 (3) ◽  
pp. 22-36
Author(s):  
Keyword(s):  
Stress Intensity ◽  
Impact Strength ◽  
Welded Joints ◽  
Development Process ◽  
Welded Joint ◽  
Operating Temperature ◽  
Crack Development ◽  
Heterogeneous Structure ◽  
Critical Crack Length ◽  
The Impact

Практика показывает, что для сварных конструкций, эксплуатируемых в условиях Крайнего Севера необходимо уделять внимание работоспособности сварных соединений при низких температурах. Металл сварных соединений в процессе воздействия обработки изменяет свои свойства, снижается ударная вязкость, образуется гетерогенная структура с большой степенью разнозернистости. Чтобы оценивать и иметь возможность правильно контролировать термическое воздействие и последствия сварочного процесса, требуется решить задачу аналитического определения ударной вязкости для всех зон сварного соединения. В настоящей статье представлен инженерный метод оценки ударной вязкости, применимый для любой зоны сварного соединения, в которой имеется острый или особый концентратор напряжений – трещина. Разработанный аналитический метод расчета ударной вязкости отражает качественную и количественную картину взаимосвязи структурно-механических характеристик и работы развития трещины в диапазоне температур 77…300 К. Предложенная схематизация зависимости критического коэффициента интенсивности напряжений от температуры позволила найти коэффициенты, характеризующие свойства материала, и выполнить расчеты изменения предела текучести и предела прочности от температуры эксплуатации. Построены графики зависимости работы развития трещины от температуры эксплуатации для сталей 15ГС и 17ГС, сравнение которых с экспериментальными данными показывает удовлетворительное согласование. Найдено, что при напряжениях предела выносливости отношение работы развития трещины к критической длине трещины постоянно, не зависит от температуры и для сталей 15ГС и 17ГС равно около 10. Ключевые слова: ударная вязкость, работа разрушения, коэффициент интенсивности напряжений, трещина, феррито-перлитная сталь, зона термического влияния. For welded structures under operation in the Far North, attention must be paid to the performance of welded joints at low temperatures. The properties of metal of welded joints are changed in the process of treatment, its toughness decreases, and a heterogeneous structure with a large range of different grain sizes is formed. In order to evaluate and be able to correctly control the thermal effect and the consequences of the welding process, it is necessary to solve the problem of analytical determination of impact strength for all zones of the welded joint. The paper presents an engineering method for evaluation of the impact strength applicable to any area of the welded joint in which there is a sharp or super sharp stress concentrator – a crack. The developed analytical method for calculating the impact strength reflects a qualitative and quantitative codependency of structural and mechanical characteristics and the process of crack development in the temperature range of 77–300 K. The proposed schematization of dependence of the critical coefficient of stress intensity on the temperature made it possible to find coefficients characterizing the properties of the material and to perform calculations of changes in yield strength and tensile strength on operating temperature. Graphs of the crack development process dependency on the operating temperature for 15ГС and 17ГС steels were constructed, and their comparison with experimental data displays satisfactory agreement. It was found that at endurance limit stresses, the ratio of the crack development process to the critical crack length is constant, non-dependent on temperature, and is equal to 10 for 15ГС and 17ГС steels. Keywords: impact strength, fracture work, stress intensity factor, crack, ferrite-pearlite steel, heat affected zone, steel tempering.

Residual Stress Release and Its Effects on the Fatigue Strength of Typical Welded Joints in Cone-Cylinder Pressure Structures

2021 ◽  
Vol 111 ◽  
pp. 102673
Author(s):  
Liangbi Li ◽  
Jingxi Zhang ◽  
Yiwen Zhang ◽  
Deqin Zhu ◽  
Zhengquan Wan ◽  
...  
Keyword(s):  
Residual Stress ◽  
Fatigue Strength ◽  
Welded Joints ◽  
Cylinder Pressure ◽  
Stress Release

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.

scholarly journals Simplified Analysis of Welding Residual Stress in a Box Structure Fabricated with Plural Welded Joints.

1999 ◽  
Vol 65 (633) ◽  
pp. 989-995 ◽  
Author(s):  
Masahito MOCHIZUKI ◽  
Toshio HATTORI ◽  
Munetoshi ZEN ◽  
Junji YAMAMOTO ◽  
Kimiaki NAKAKADO
Keyword(s):  
Residual Stress ◽  
Welded Joints ◽  
Welding Residual Stress ◽  
Box Structure ◽  
Simplified Analysis

Welding Residual Stress Evaluation of Complex Welded Joints by Brinell Hardness Method

2014 ◽  
Vol 496-500 ◽  
pp. 2444-2451
Author(s):  
Qiang Zeng ◽  
Dai Qin Tao ◽  
Zheng Zhou ◽  
Xiao Qian Li
Keyword(s):  
Residual Stress ◽  
Statistical Analysis ◽  
Base Metal ◽  
Welded Joints ◽  
Brinell Hardness ◽  
Welding Residual Stress ◽  
Stress Evaluation ◽  
Material Hardness

Basing on a giant truss, this passage did a macro assessment of welding resjdual stress by the changes of material hardness which was measured by brinell hardness method after welding. This experiment measured about 1728 measurement points on 72 nodes. Statistical analysis of the hardness data shows that hardness of base metal decreases in the area of HAZ ,and plastic of welded joints increases.

Effect of residual stress on the cold-resistance and endurance of welded joints

1989 ◽  
Vol 21 (7) ◽  
pp. 891-896
Author(s):  
V. P. Larionov ◽  
V. G. Petushkov ◽  
G. P. Yakovlev
Keyword(s):  
Residual Stress ◽  
Welded Joints ◽  
Cold Resistance

Fatigue Assessment of Welded Joints Taking Into Account Effects of Residual Stress

2010 ◽  
Author(s):  
Nur Syahroni ◽  
Stig Berge
Keyword(s):  
Residual Stress ◽  
Fatigue Strength ◽  
Welded Joints ◽  
Fatigue Testing ◽  
International Association ◽  
Hot Spot ◽  
Mean Stress ◽  
Element Analysis ◽  
Structural Rules ◽  
Fatigue Design

Residual stress may have a significant effect on the fatigue strength of welded joints. As a non-fluctuating stress, it has an effect similar to that of the mean stress. Recently the International Association of Ship Classification Societies (IACS) has issued Common Structural Rules (CSR) for respectively tankers (IACS 2006a) and bulk carriers (IACS 2006b). The effect of mean stress in fatigue design is taken into account in both sets of rules. However, the treatment is quite different, in particular with regard to residual stress and shakedown effects. In the present paper a comparative study of fatigue design procedures of the IACS rules is reported, with emphasis on residual stress effects. Testing was carried out with longitudinal attachment welds in the as-welded condition. The initial residual stress was measured by a sectioning method using strain gages. Hot spot stress was determined experimentally by strain gauges and numerically by finite element analysis using different types of elements. Fatigue testing was carried out and SN-curves were plotted according to the relevant stress as specified by the rules. In order to investigate the shake-down effect of residual stress, testing was performed for several pre-load conditions which could be taken to represent maximum load levels in a load history. The aim of the study is to contribute towards better understanding of the effect of residual stress and shakedown on fatigue strength of welded joints.

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