Limiting Flaw Size Evaluation for Welded Austenitic Stainless Steels: A Comparison of Section XI Appendix C and Appendix H Approaches

2016 ◽  
Author(s):  
John E. Broussard
Keyword(s):  
Residual Stress ◽  
Internal Pressure ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Flaw Size ◽  
Welding Residual Stress ◽  
The Other ◽  
Analytical Evaluation ◽  
Failure Assessment ◽  
Size Evaluation

Paragraph IWB-3641 of Section XI [1] permits the use of Nonmandatory Appendix C or H to perform the analytical evaluation of flaws in austenitic and ferritic piping. When considering welded austenitic material, Appendix C does not include the welding residual stress as an input to the calculations for maximum allowable flaw length and depth. In contrast, Appendix H does include the welding residual stress when the K′r coordinate on the failure assessment diagram curve is calculated for austenitic materials. This paper calculates the maximum allowable axial and circumferential flaws in a welded austenitic component subject to internal pressure loads using Appendix C procedures and using Appendix H procedures. The results are compared to investigate cases where a flaw may be acceptable using one set of procedures and not acceptable using the other.

The Effect of Boron on the Corrosion Resistance of Austenitic Stainless Steels

CORROSION ◽  
1977 ◽  
Vol 33 (11) ◽  
pp. 408-417 ◽  
Author(s):  
F. P. A. ROBINSON ◽  
W. G. SCURR
Keyword(s):  
Corrosion Resistance ◽  
Stainless Steels ◽  
Intergranular Corrosion ◽  
Detrimental Effect ◽  
Austenitic Stainless Steels ◽  
The Other ◽  
Beneficial Effects ◽  
Identical Series ◽  
Type 304 ◽  
Intergranular Corrosion Resistance

Abstract Two Type 304 stainless steels, one boron free and the other containing 4 ppm boron were investigated. Both steels were subjected to an identical series of corrosion tests and the results compared with one another. It was found (1) Boron had no detrimental effect on the potentiostatic characteristics, intergranular corrosion “resistance and pitting resistance of the steels in the “as-received” condition; (2) boron in solid solution had no detrimental effect on the potentiostatic characteristics and intergranular corrosion resistance of the steel, while boron in solution had a beneficial effect on the pitting resistance of the steel, and (3) boron retarded Cr23C6 precipitation and thus boron had marked beneficial effects on the intergranular corrosion resistance of the steels in a sensitized condition. In addition the potentiostatic characteristics and pitting resistance of such steels were improved slightly by the presence of boron.

Effect of Strain-Induced Martensitic Transformation on Coaxing Effect of Austenitic Stainless Steels

2008 ◽  
Vol 385-387 ◽  
pp. 505-508
Author(s):  
Jae Woong Jung ◽  
Masaki Nakajima ◽  
Yoshihiko Uematsu ◽  
Keiro Tokaji ◽  
Masayuki Akita
Keyword(s):  
Martensitic Transformation ◽  
Stainless Steels ◽  
Work Hardening ◽  
Strain Aging ◽  
Austenitic Stainless Steels ◽  
Fatigue Tests ◽  
The Other ◽  
Conventional Tests ◽  
Materials Used ◽  
Type 304

The effects of martensitic transformation on the coaxing behavior were studied in austenitic stainless steels. The materials used were austenitic stainless steels, type 304 and 316. Conventional fatigue tests and stress-incremental fatigue tests were performed using specimens subjected to several tensile prestrains from 5% to 60%. Under conventional tests, the fatigue strengths of both steels increased with increasing prestrain. Under stress-incremental tests, 304 steel showed a marked coaxing effect, where the failure stress significantly increased irrespective of prestrain level. On the other hand, the coaxing effect in 316 steel decreased with increasing prestrain up to 15%, where the failure stresses were nearly the same. Above this prestrain level, the coaxing effect increased with increasing prestrain. In 304 steel, the coaxing effect is primarily dominated by work hardening at low prestrains, while the effect of strain-induced martensitic transformation increases with increasing prestrain. The coaxing effect in 316 steel is dominated by both work hardening and strain aging at low prestrains, but strain-induced martensitic transformation could play a significant role at high prestrains.

Retardation Effect of Cyclic Overload on Stress Corrosion Crack Growth in Stainless Steel

2017 ◽  
Author(s):  
Toshiyuki Saito ◽  
Takahiro Hayashi ◽  
Chihiro Narazaki ◽  
Mikiro Itow
Keyword(s):  
Stress Corrosion ◽  
Stainless Steels ◽  
Power Plants ◽  
Structural Integrity ◽  
Plastic Region ◽  
Austenitic Stainless Steels ◽  
Growth Behavior ◽  
Welding Residual Stress ◽  
Earthquake Force ◽  
Cyclic Overload

Stress Corrosion Cracking (SCC) has been observed in some components of austenitic stainless steels in the Boiling Water Reactors (BWRs). The structural integrity evaluation for flawed component is performed for continued service for a specified time period based on the Rules on Fitness-for-Service (FFS) for Nuclear Power Plants, such as JSME FFS Code or ASME Section XI. SCC growth evaluation is generally performed only by taking into account steady loads, such as welding residual stress. It is important to examine various factors affecting SCC growth behavior for further understanding and improvement in predicting growth behavior in the BWR environment. Cyclic overloading due to such as earthquake force is one of the important factors to be evaluated. In this study, the effect of cyclic overload on SCC growth in simulated BWR environment has been examined by using CT specimens of cold-rolled stainless steels (Type 316L). The retardation phenomenon was observed in SCC growth behavior immediately after the cyclic overloading was applied. It was considered that SCC propagation was retarded due to the compressive plastic region at the crack tip, introduced by overloads. The method of predicting the SCC growth behavior after cyclic overloading was also discussed.

Assessing Brittle Fracture in Pressurized Equipment Using a FAD

2008 ◽  
Author(s):  
David R. Thornton
Keyword(s):  
Fracture Mechanics ◽  
Brittle Fracture ◽  
Flaw Size ◽  
The Other ◽  
Failure Assessment Diagram ◽  
Failure Assessment

While the probability of brittle fracture in pressurized equipment has typically been rare, the consequences are usually unacceptable from a risk standpoint. This article first briefly reviews the method used to prevent brittle fracture in new equipment used by most codes. The article then presents the approaches of increasing complexity to preventing brittle fracture in existing equipment with an emphasis on the fracture mechanics approach and the use of a Failure Assessment Diagram (FAD). Two examples are discussed, one of determining the maximum acceptable flaw size for a given operating scenario and the other of determining an acceptable operating envelope for a given flaw size.

Effects of Post Weld Heat Treatment Residual Stress on the Creep of Elbow Welded Joint

2009 ◽  
Author(s):  
Changyu Zhou ◽  
Guodong Zhang
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
High Temperature ◽  
Internal Pressure ◽  
Creep Strain ◽  
Welded Joint ◽  
Post Weld Heat Treatment ◽  
Welding Residual Stress ◽  
Creep Analysis ◽  
Boiler Tubes

It is well known that type IV crack emerges in the high temperature welded components. Although the welding residual stress will drop after post weld heat treatment (PWHT), the PWHT residual stress still remains in the welded joint. When the joint is in service at high temperature and under high pressure, the PWHT stress and pressure will induce the creep strain in the welded joint of the elbow of T91 boiler tubes. Usually, it is considered that the PWHT stress will relax at high temperature environment and is ignored by many researchers. In this paper, by the finite element analysis codes ABAQUS and the function of RESTART, a sequential coupling calculating program for creep based on welding residual stress has been developed by establishing the model of temperature field, residual stress and creep analysis. The welding residual stress and creep of elbow welded joint for T91 boiler tubes was simulated by the program. According to the finite element calculation results, the PWHT stress has a great influence on the T91tube creep. This method established the basis of calculating the effects of welding residual stress on the creep of welded joint. Firstly, the welding residual stress and the PWHT stress was simulated by ABAQUS. Based on the work, the stress distribution of the T91 tube elbow can be obtained under internal pressure and the PWHT stress. Secondly, for the elbow welded joint the creep under the internal pressure only and the creep under internal pressure and PHWT stress can be simulated by the ABAQUS codes. Then comparison of creep strain in the elbow welded joint with PWHT stress and with internal pressure is made in the paper. Although the stress induced by the PWHT and internal pressure would relax in a short time, the creep strain of the elbow welded joint is still influenced by initial stress state. The results shown that the PWHT stress can not be ignored for the creep analysis of the elbow welded joint. So it can be considered that the PWHT residual stress is one of possible failure factors for the elbow welded joint. The design of high temperature elbow welded joint need to consider the influence of the PWHT residual stress. This paper will provide a more comprehensive means for life assessment of the welded joint in service.

Strategy of Considering Microstructural Effect on Weld Residual Stress Analysis

2004 ◽  
Author(s):  
Masahito Mochizuki ◽  
Masao Toyoda
Keyword(s):  
Residual Stress ◽  
Thermal Stress ◽  
Stress Analysis ◽  
Stainless Steels ◽  
High Strength Steels ◽  
Austenitic Stainless Steels ◽  
High Strength ◽  
Weld Residual Stress ◽  
Residual Stress Analysis ◽  
Microstructural Effect

Thermal distortion and residual stress are essentially generated by welding and it is well known that they affect the performance of welded structures such as brittle fracture, fatigue, buckling deformation, and stress-corrosion cracking. Welding distortions and residual stresses can be possible controlled and reduced by using some countermeasures. Not only thermal stress behavior but also prediction of microstructural phase during weld heat cycles are very important. High strength steels or martensitic stainless steels are used in a lot of power plant components, and the effect of phase transformation on mechanical behavior during welding in these steels becomes much larger than that of mild steels and austenitic stainless steels. Simultaneous simulation between thermal stress and microstructure during welding should be necessary in a precise evaluation. Analytical method and several applications to actual components are introduced in order to emphasize the effect considering microstructure on weld residual stress analysis.

scholarly journals Flaw Stability Considering Residual Stress for Aging Management of Spent Nuclear Fuel Multiple-Purpose Canisters

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Poh-Sang Lam ◽  
Robert L. Sindelar
Keyword(s):  
Residual Stress ◽  
Nuclear Fuel ◽  
Spent Nuclear Fuel ◽  
Stress Relief ◽  
Storage Conditions ◽  
Welding Residual Stress ◽  
Long Term Storage ◽  
Failure Assessment ◽  
Term Storage

A typical multipurpose canister (MPC) is made of austenitic stainless steel and is loaded with spent nuclear fuel (SNF) assemblies. Because heat treatment for stress relief is not required for the construction of the MPC, the canister is susceptible to stress corrosion cracking in the weld or heat affected zone (HAZ) regions under long-term storage conditions. Logic for flaw acceptance is developed should crack-like flaws be detected by Inservice Inspection. The procedure recommended by API 579-1/ASME FFS-1, Fitness-for-Service, is used to calculate the instability crack length or depth by failure assessment diagram (FAD). It is demonstrated that the welding residual stress (RS) has a strong influence on the results.

Applicability of Friction Stir Welding to steels

2017 ◽  
Vol 2 (80) ◽  
pp. 65-85 ◽  
Author(s):  
G. Çam ◽  
G. İpekoğlu ◽  
T. Küçükömeroğlu ◽  
S.M. Aktarer
Keyword(s):  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
High Strength ◽  
Cost Effective ◽  
Industrial Applications ◽  
Fusion Welding ◽  
The Other ◽  
Friction Stir ◽  
Fusion Weld ◽  
Welding Processes

significant developments in joining technology to emerge in the last 30 years. The technique has originally been developed for joining difficult-to-fusion-weld Al-alloys, particularly for high strength grades and now widely used in various industrial applications, such as transport industries. On the other hand, the application of FSW to high temperature materials such as steels is hindered due to the problems associated with the stirring tools although there is a wide interest for the application of this technique to these materials. Design/methodology/approach: The aim of this review is to address the current state-of-the-art of FSW of steels, focusing particularly on microstructural aspects and the resulting properties of these joints and discuss the future prospects of this technique for steels. For instance, the use of FSW can be advantageous for joining steels in some special applications where conventional fusion welding processes fail to produce sound cost effective joints, and the high tooling costs of FSW can be justified (i.e. underwater joining of steel pipes or hot plate welding in steel mills). In this study, only structural steels (mainly plain C steels), ferritic stainless steels, austenitic stainless steels and duplex stainless steels will be considered and the other types of steels are out of the scope of this work although some examples are included in the discussion. Research limitations/implications: The tools experience high temperatures in FSW of steels, i.e., above 1000°C. The number of tool materials which can withstand such temperatures is very limited. In addition, the welding of many common steels can be readily conducted by various conventional fusion welding methods. These joining methods are very flexible, easy-to-perform and well established in industrial applications, which further prevents the application of FSW to these materials. These limitations are to be overcome for commercial exploitation of this technique for joining steels.

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