The influence of residual stresses on fracture behavior of Pipe Ring Notched Bend specimen (PRNB)

2019 ◽  
Vol 205 ◽  
pp. 347-358 ◽  
Author(s):  
D. Damjanović ◽  
D. Kozak ◽  
N. Gubeljak
Keyword(s):  
Residual Stresses ◽  
Fracture Behavior ◽  
Bend Specimen

Weld Residual Stress and Fracture Behavior of NASA Layered Pressure Vessels

2019 ◽  
Author(s):  
F. W. Brust ◽  
R. H. Dodds ◽  
J. Hobbs ◽  
B. Stoltz ◽  
D. Wells
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Fracture Behavior ◽  
Service Evaluation ◽  
Pressure Vessels ◽  
Weld Residual Stress ◽  
Proof Testing ◽  
Fracture Assessment ◽  
High Level ◽  
Initial Results

Abstract NASA has hundreds of non-code layered pressure vessel (LPV) tanks that hold various gases at pressure. Many of the NASA tanks were fabricated in the 1950s and 1960s and are still in use. An agency wide effort is in progress to assess the fitness for continued service of these vessels. Layered tanks typically consist of an inner liner/shell (often about 12.5 mm thick) with different layers of thinner shells surrounding the inner liner each with thickness of about 6.25-mm. The layers serve as crack arrestors for crack growth through the thickness. The number of thinner layers required depends on the thickness required for the complete vessel with most tanks having between 4 and 20 layers. Cylindrical layers are welded longitudinally with staggering so that the weld heat affected zones do not overlap. The built-up shells are then circumferentially welded together or welded to a header to complete the tank construction. This paper presents some initial results which consider weld residual stress and fracture assessment of some layered pressure vessels and is a small part of the much larger fitness for service evaluation of these tanks. This effort considers the effect of weld residual stresses on fracture for an inner layer longitudinal weld. All fabrication steps are modeled, and the high-level proof testing of the vessels has an important effect on the final WRS state. Finally, cracks are introduced, and service loading applied to determine the effects of WRS on fracture.

Analysis of HAZ Fracture Toughness of Duplex Stainless Steel Weldment

2009 ◽  
Author(s):  
C. S. Pathak ◽  
L. G. Navale ◽  
A. D. Sahasrabudhe ◽  
M. J. Rathod
Keyword(s):  
Fracture Toughness ◽  
Stainless Steel ◽  
Fracture Mechanics ◽  
Residual Stresses ◽  
Duplex Stainless Steel ◽  
Fracture Behavior ◽  
Health And Safety ◽  
Steel Weldment ◽  
Welded Structure ◽  
Stainless Steel Weldment

Most of the serious weldment failures lead to catastrophic consequences in terms of damage to other equipment, loss of production, and risks to workers’ health and safety. Hence there is motivation to find margin between safety and disaster. This necessitates guaranteeing the integrity of a welded structure even if a crack is present. Therefore influence of the material inhomogenity and residual stresses on deformation and fracture behavior needs to be described precisely. A comparison of the applied load with a convenient material parameter is necessary for this purpose. Fracture mechanics parameters J integral & CTOD have attracted great interest in recent years. In case of base materials, fracture mechanics works quite well, but some specific problems occur if fracture mechanics principles are applied when examining the toughness properties of welded joints. These problems are mainly caused by the large difference in material properties and residual stresses. Existing fracture toughness testing can predict fracture behavior, but does not sufficiently address the problem associated with weldment testing. Three SENB duplex stainless steel weldment specimens were tested as per ASTM E1820. This standard is not recommended for weldment, but since no standard is available for testing duplex stainless steel weldment, authors preferred to use it as reference. The aim of this work is to explore the possibility of using the test results in the reliable prediction of weldment fracture and its correlation with microstructure and hardness.

Effect of Residual Forming Stresses on Fracture in ERW Pipe

2016 ◽  
Author(s):  
Ted L. Anderson ◽  
Gregory W. Brown
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Fracture Behavior ◽  
Finite Element Simulations ◽  
Finite Element Analyses ◽  
Forming Process ◽  
Cold Expansion ◽  
The Past

Many older pipelines contain significant residual stress due to the forming process. Cold expansion or a normalizing heat treatment can virtually eliminate residual forming stresses, but these practices were less common in the past. In the absence of cold expansion or normalization, residual forming stresses can be reduced by hydrostatic testing or operating pressures, but not eliminated entirely. Residual stresses can contribute to fracture in pipelines, particularly when the material toughness is low. This article presents a series of analyses that seek to quantify the magnitude of residual forming stresses as well as their impact on pipeline integrity. The pipe forming process was simulated with elastic-plastic finite element analyses, which considered the effect of subsequent loading on relaxation of residual stresses. A second set of finite element simulations were used to quantify the effect of residual stresses on fracture behavior.

Analysis and fracture behavior of welded box beam-to-column connections considering residual stresses

2017 ◽  
Vol 154 ◽  
pp. 557-566 ◽  
Author(s):  
Jianrong Pan ◽  
Shizhe Chen ◽  
Zhichao Lai ◽  
Zhan Wang ◽  
Junqi Wang ◽  
...  
Keyword(s):  
Residual Stresses ◽  
Fracture Behavior ◽  
Box Beam
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