Technical Basis for Expansion of ASME BPVC Section XI, KIC Curve Applicability

2019 ◽  
Author(s):  
Hongqing Xu ◽  
Nathan Palm ◽  
Anees Udyawar
Keyword(s):  
Fracture Toughness ◽  
Lower Bound ◽  
Fracture Mechanics ◽  
Yield Strength ◽  
Room Temperature ◽  
Ferritic Steels ◽  
Initiation Toughness ◽  
Room Temperature Yield Strength ◽  
Class 1 ◽  
Technical Basis

Abstract When the Appendix G methodology, fracture toughness criteria for protection against failure, was first adopted by ASME Section III in 1972, it included a lower-bound Kir curve for ferritic steels with specified minimum room-temperature yield strength up to 50 ksi. In 1977, Section III Appendix G added a requirement to obtain fracture-toughness data for at least three heats (base metal, weld metal, and heat-affected zone) if the KIR curve is used for ferritic steels with specified minimum room-temperature yield strength between 50 and 90 ksi. The three-heat data requirement has not changed when the lower bound curve was adopted by Section XI, or when the lower-bound crack initiation toughness curve was changed from the dynamic Kir curve to the static KIc curve during the 2000s. Based on the accumulation of fracture-mechanics data of ferritic steels with specified minimum yield strength between 50 ksi and 90 ksi and their use for Class 1 pressure vessel production, Section XI recently expanded the applicability of the KIc curve to SA-508 Grade 2 Class 2, SA-508 Grade 3 Class 2, SA-533 Type A Class 2, and SA-533 Type B Class 2 whose specified minimum room-temperature yield strength is 65 ksi or 70 ksi. This paper describes the technical basis including the fracture-mechanics data to support the expansion of the applicability of the KIc curve by ASME Section XI.

Technical Basis for Revised Flaw Acceptance Criteria Under IWB-3610 of ASME Section XI

2005 ◽  
Author(s):  
Russell C. Cipolla ◽  
Keith R. Wichman
Keyword(s):  
Fracture Toughness ◽  
Lower Bound ◽  
Input Parameter ◽  
Fracture Initiation ◽  
Reference Curve ◽  
Acceptance Criteria ◽  
Class 1 ◽  
Reference Curves ◽  
Static Fracture ◽  
Technical Basis

This paper describes the change from the KIa to KIc in performing flaw evaluation for Class 1 ferritic steel components according to IWB-3610 and Appendix A of the ASME Boiler and Pressure Vessel Code, Section XI. The primary reason for making this change is to reduce the excess conservatism in the current flaw evaluation acceptance criteria. The Appendix A calculation methods can be used in accepting flaws detected as part of the plant inservice inspection program. The KIa and KIc reference curves represent two lower bound fracture toughness curves available in ASME Section XI. The KIa reference curve is a lower bound on all static, dynamic and arrest fracture toughness, whereas the KIc reference curve is a lower bound on static fracture toughness only. A similar change has already been implemented in the calculation of the heatup and cooldown pressure-temperature (P-T) limit curves, which are also based on fracture mechanics analysis. The P-T limits are developed according to Appendix G of Section XI, which employ similar methods to those of Appendix A. A key input parameter to the P-T calculations is the lower bound fracture toughness curve, KIc (prior to change in Appendix G, the lower bound curve KIR was used, which was equivalent to KIa). Based on the work described in this technical basis paper, Section XI recently approved the change from KIa to KIc in IWB-3610. In addition, changes to the use of KIc for fracture initiation, changes were also made to IWB-3613, which provides acceptance criteria for flanges and other shell regions near structural discontinuities. These changes clarified the scope of the article as to what discontinuities are covered and a redefinition for the minimum temperature from RTNDT + 60°F (RTNDT + 33°C) to just RTNDT. These changes are also discussed in this paper. The changes will appear in the 2005 addenda to the 2004 Code Edition for Section XI.

RMI 6Al-ELI

Alloy Digest ◽  
1988 ◽  
Vol 37 (12) ◽  
Keyword(s):  
Fracture Toughness ◽  
High Pressure ◽  
Room Temperature ◽  
Base Alloy ◽  
Heat Treating ◽  
Age Hardening ◽  
Bend Strength ◽  
Annealed Condition ◽  
Room Temperature Yield Strength ◽  
Alpha Beta

Abstract RMI 6A1-4V ELI is an alpha-beta type of titanium-base alloy that can be strengthened by age hardening. In the mill-annealed condition it has a guaranteed minimum room-temperature yield strength of 120,000 psi and can be increased to as much as 160,000 psi by solution treating and aging. This alloy may be used for high-pressure cryogenic vessels down to 320 F. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and bend strength as well as fracture toughness. It also includes information on corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Ti-89. Producer or source: RMI Company.

Technical Basis of Proposed New Acceptance Standards for Class 1, 2 and 3 Piping

2007 ◽  
Author(s):  
Katsumasa Miyazaki ◽  
Kunio Hasegawa ◽  
Naoki Miura ◽  
Koichi Kashima ◽  
Douglas A. Scarth
Keyword(s):  
Fracture Mechanics ◽  
Ultrasonic Inspection ◽  
Limit Load ◽  
Flaw Size ◽  
High Fracture Toughness ◽  
Evaluation Procedure ◽  
High Fracture ◽  
Development Methodology ◽  
Class 1 ◽  
Technical Basis

Acceptance Standards in Section XI of the ASME Boiler and Pressure Vessel Code have an important role as the first step in the flaw evaluation procedure. When a flaw size is within the allowable flaw size in the Acceptance Standard, the flaw is acceptable and analytical evaluation is not required. Although ASME Section XI has Acceptance Standards for Class 1 piping in IWB-3500, there are no Acceptance Standards for Class 2 and 3 piping. Furthermore, the development of the current Acceptance Standards for Class 1 piping was based on flaw detectability by ultrasonic inspection and consideration of fracture mechanics. In this paper, the development of proposed new Acceptance Standards for Class 2 and 3 piping, as well as for Class 1 piping, is described. The development methodology is based on a fracture mechanics approach. For Class 1 piping with high fracture toughness, the allowable flaw sizes were determined by limit load solution. For Class 1 piping, the intent was to maintain overall consistency with the current Acceptance Standards. Proposed Acceptance Standards for Class 2 and 3 austenitic piping were also developed by the methodology used to develop the proposed new Acceptance Standards for Class 1 piping. Allowable flaw sizes for both surface flaws and subsurface flaws for preservice and inservice examinations were developed.

Fracture Mechanics of Y2O3 Ceramics at High Temperatures

2014 ◽  
Vol 89 ◽  
pp. 88-93
Author(s):  
Marek Boniecki ◽  
Zdzislaw Librant ◽  
Władysław Wesołowski ◽  
Magdalena Gizowska ◽  
Marcin Osuchowski ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Grain Size ◽  
High Temperature ◽  
Fracture Mechanics ◽  
High Purity ◽  
Room Temperature ◽  
Bending Strength ◽  
Hot Isostatic Pressing ◽  
Temperature Changes ◽  
Four Point Bending

Fracture toughness KIc and four-point bending strength σc at high temperature (up to 1500 °C) of Y2O3 ceramics of various grain size were measured. The ceramics were prepared by pressureless air sintering and next hot isostatic pressing of high purity (99.99%) Y2O3 powder. Relative density of about 99 % was achieved. Photos of microstructures revealed small pores distributed mainly inside grains. For smallest grain size (2 - 9 μm) ceramics KIc and σc are almost constant from 20 ° to 1200 °C and next they decrease. For biggest grain size (about 44 μm) they increase up to 800 °C and next they keep constant up to 1200 °C. The micrographs analyses of fracture surfaces indicated that transgranular mode of fracture at room temperature changes to almost intergranular at higher temperatures.

scholarly journals A Statistical Model of Cleavage Fracture Toughness of Ferritic Steel DIN 22NiMoCr37 at Different Temperatures

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 982 ◽  
Author(s):  
Guian Qian ◽  
Wei-Sheng Lei ◽  
Zhenfeng Tong ◽  
Zhishui Yu
Keyword(s):  
Fracture Toughness ◽  
Yield Strength ◽  
Statistical Model ◽  
Cleavage Fracture ◽  
Failure Probability ◽  
Ferritic Steel ◽  
Ferritic Steels ◽  
Local Approach ◽  
Weibull Statistics ◽  
Different Temperatures

It is a conventional practice to adopt Weibull statistics with a modulus of 4 for characterizing the statistical distribution of cleavage fracture toughness of ferritic steels, albeit based on a rather weak physical justification. In this study, a statistical model for cleavage fracture toughness of ferritic steels is proposed according to a new local approach model. The model suggests that there exists a unique correlation of the cumulative failure probability, fracture toughness and yield strength. This correlation is validated by the Euro fracture toughness dataset for 1CT specimens at four different temperatures, which deviates from the Weibull statistical model with a modulus of four.

Repair of Class 1 Control Rod Drive and In-Core Housing Bottom Head Penetrations in BWRs

2005 ◽  
Author(s):  
Greg Harttraft ◽  
Roy Corieri ◽  
Sam Ranganath ◽  
Ken Wolfe ◽  
H. William McCurdy ◽  
...  
Keyword(s):  
Fracture Mechanics ◽  
Radiation Exposure ◽  
Field Experience ◽  
Expansion Process ◽  
Control Rod ◽  
Water Reactor ◽  
Mechanics Analysis ◽  
Class 1 ◽  
Process Qualification ◽  
Technical Basis

The ASME Section XI committee is developing a code case to permit repair of leakage on Boiling Water Reactor (BWR) bottom head penetrations with a mechanical roll expansion process. This technology has been successfully utilized for this application over the last two decades to address leakage due to Control Rod Drive (CRD) stub tube cracking. The code case defines the technical and administrative requirements for use of the mechanical roll expansion process for repair of Class 1 Control Rod Drive and Incore housing penetrations in the bottom head of BWRs. The code case specifies the process qualification, essential variables, process application, examination and pressure testing requirements for this process. The technical basis of the proposed code case includes detailed fracture mechanics analysis to evaluate the structural consequences of the cracking, metallurgical assessment and extensive testing to determine the load capability of the roll repair joint. Based on this assessment, the successful BWR field experience and the inspections/ qualifications required under the code case, the mechanical roll expansion repair can be used as a permanent repair option for addressing leakage in BWR CRD and In-core housing penetrations, The application of this code case will provide significant reduction in facility down time and will offer a reduction in personnel radiation exposure as compared to welded repair options.

The Non-Effect of Yield Strength on RTT0 and on the Master Curve

2019 ◽  
Author(s):  
Mark Kirk ◽  
Marjorie Erickson
Keyword(s):  
Fracture Toughness ◽  
Yield Strength ◽  
Cleavage Fracture ◽  
Working Group ◽  
Master Curve ◽  
Room Temperature ◽  
Code Change ◽  
Underlying Mechanisms ◽  
Operating Plant

Abstract During the August 2018 ASME Committee Week, a Code Change Inquiry was presented to the Working Group on Operating Plant Criteria (WGOPC): Question 1: Is it the intent of G-2110 to limit RTT0 use to ferritic materials with specified minimum room temperature yield strengths 50 ksi or less? Question 2: If the reply to Question 1 is “No”, is it the intent of G-2110 that G-2110(b) requirement must be met before RTT0 may be used for ferritic materials above 50 ksi but not exceeding 90 ksi? During that meeting the WGOPC replied “no” to both questions. This paper provides an evaluation of available fracture toughness data augmented by an understanding of the underlying mechanisms of cleavage fracture to demonstrate the veracity of the WGOPC’s answer with regards to RTT0 and, more generally, with respect to the Master Curve.

Observation of slip propagation across grain boundaries in Ni3Al

1986 ◽  
Vol 44 ◽  
pp. 864-865 ◽  
Author(s):  
I. Baker ◽  
E.M. Schulson ◽  
J.A. Horton
Keyword(s):  
Grain Size ◽  
Yield Strength ◽  
Room Temperature ◽  
Size Dependence ◽  
Direct Evidence ◽  
Specimen Preparation ◽  
Fine Grained ◽  
Room Temperature Yield Strength ◽  
Pile Up ◽  
Preparation Techniques

Recent modelling of the grain size dependence of the room-temperature yield strength of Ni3Al has invoked the concept of dislocation pile-ups. The idea is that the yield strength measured in the Liiders regime (i.e. the Liiders band propagation stress) represents not the stress to independently nucleate slip in each grain but the stress required to propagate slip through the material. This paper presents direct evidence of slip propagation from one grain to the next and thus validation of the use of a pile-up model for Ni3Al.Miniature tensile specimens (3 mm x 7 mm x0.2 mm), made from an extruded rod of fine-grained (∽10 μm) Ni3Al containing 0.35 at.% boron, were strained under tension whilst being observed in a Philips EM 430T operated at 300 KV. Details of the design and operation of the straining stage and of the specimen preparation techniques are given elsewhere.

RMI 5Al-2.5Sn ELI

Alloy Digest ◽  
1980 ◽  
Vol 29 (2) ◽  
Keyword(s):  
Fracture Toughness ◽  
Yield Strength ◽  
Room Temperature ◽  
Heat Treating ◽  
Pressure Vessels ◽  
Cryogenic Temperatures ◽  
Bend Strength ◽  
Temperature Performance ◽  
Alpha Titanium ◽  
Minimum Yield

Abstract RMI 5A1-2.5Sn ELI (ELI = Extra Low Interstitials) is an alpha titanium alloy that was developed for use at cryogenic temperatures. It has a guaranteed minimum yield strength of 100,000 psi at room temperature with good ductility and formability; its yield strength and elongation increase substantially as temperature is lowered. It is used successfully for high-pressure vessels at temperatures below -320 F. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and bend strength as well as fracture toughness. It also includes information on low temperature performance and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Ti-75. Producer or source: RMI Company.

Investigation of NiAl–TiB2in situcomposites

1997 ◽  
Vol 12 (4) ◽  
pp. 1083-1090 ◽  
Author(s):  
J. T. Guo ◽  
Z. P. Xing
Keyword(s):  
Fracture Toughness ◽  
Yield Strength ◽  
Hot Pressing ◽  
Room Temperature ◽  
Tensile Yield Strength ◽  
Matrix Composites ◽  
Orientation Relationships ◽  
The Matrix ◽  
Atomically Flat ◽  
Nial Matrix

A hot-pressing aided exothermic synthesis (HPES) technique to fabricate NiAl matrix composites containing 0 and 20 vol.% TiB2 particles was developed. The conversion of mixtures of elements to the product was complete after processing, and TiB2 particles in the matrix were uniformly dispersed. The microstructure and interfaces were very thermally stable. The interfaces between NiAl and TiB2 were atomically flat, sharp, and generally free from interfacial phases. In some cases, however, thin amorphous layers existed at NiAl/TiB2 interfaces. At least three kinds of orientation relationships between TiB2 and NiAl were observed. The compressive yield strengths at room temperature and at 1000 °C of the composite were approximately three times as strong as those of the unreinforced NiAl. The tensile yield strength at 980 °C of the composite was about three times stronger than that of NiAl. The ambient fracture toughness of the composite was slightly greater than that of the monolithic NiAl.

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