Influence of Testing Environment and Radius of Die Shoulder on SP Creep Rupture Life

2011 ◽  
Author(s):  
Ken-ichi Kobayashi ◽  
Masahiro Kaneko ◽  
Hideo Koyama ◽  
Gavin C. Stratford ◽  
Masaaki Tabuchi
Keyword(s):  
Oxide Scale ◽  
Rupture Life ◽  
High Vacuum ◽  
Creep Rupture ◽  
Test Duration ◽  
Creep Life ◽  
Destructive Testing ◽  
Creep Tests ◽  
Testing Environment ◽  
High Temperature Components

Small Punch, hereinafter designated as SP, creep test has been proposed as a semi destructive testing methodology to examine the residual creep life of high temperature components. Employing low alloy steel, a series of SP creep tests were conducted on disc specimens at 600°C in air and in high vacuum to investigate the influence of oxide scale on the creep rupture life. Thickness of the oxide scale on disc specimens in air increased with the test duration, e.g., about 30μm in thickness after 400 hours. The creep rupture life in air reduced to a half of the life in vacuum due to an increase in the actual stress in the disc thickness. In addition, the magnitude of radius of a lower die shoulder affected the SP creep rupture life. The influence of this radius on the SP creep life was also studied experimentally and numerically. The creep rupture life with the die radius of 0.5mm had twice longer than that with 0.6mm. This fact was also demonstrated by the FE analysis.

Influence of Testing Environment on SP Creep Rupture Lives

2013 ◽  
Author(s):  
Ken-ichi Kobayashi ◽  
Sho Takei
Keyword(s):  
Oxide Scale ◽  
Residual Life ◽  
Rupture Life ◽  
High Vacuum ◽  
Creep Rupture ◽  
Test Duration ◽  
Destructive Testing ◽  
Creep Tests ◽  
Testing Environment ◽  
High Temperature Components

Small Punch (SP) Creep test has been recognized as a semi destructive testing method to examine residual life of creep in high temperature components. Employing 2.25Cr-1Mo steel (SCMV4), SP creep tests were conducted at 600°C both in air and in high vacuum to examine the influence of oxidation on the long-term rupture life of the SP creep tests. As a test result, the creep rupture life in air was shorter than that in vacuum when the rupture life was less than 1000 hours. Reduction of rupture lives in air was approximately a half of them tested in vacuum. However when the creep rupture life was longer than 1000 hours, little difference emerged even if the testing atmosphere was different. A thickness of the oxide scale formed on SP creep specimens in air increased with the test duration. The experimental test results showed that the oxide scale affected on a coefficient of friction between the loading ball and the SP creep specimen. Furthermore the oxide scale formed in air did not always peel off from the test specimen, and the thick oxide scale endured a part of applied load in the longer life test.

Effects of microstructure and lattice misfit on creep life of Ni-based single crystal superalloy during long-term thermal exposure

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Wenyan Gan ◽  
Hangshan Gao ◽  
Haiqing Pei ◽  
Zhixun Wen
Keyword(s):  
Single Crystal ◽  
Rupture Life ◽  
Precipitation Amount ◽  
Lattice Misfit ◽  
Thermal Exposure ◽  
Phase Evolution ◽  
Creep Rupture ◽  
Simultaneous Increase ◽  
Creep Life ◽  
The Matrix

Abstract According to the microstructural evolution during longterm thermal exposure at 1100 °C, the creep rupture life of Ni-based single crystal superalloys at 980 °C/270 MPa was evaluated. The microstructure was characterized by means of scanning electron microscopy, X-ray diffraction and related image processing methods. The size of γ’ precipitates and the precipitation amount of topologically close-packed increased with the increase in thermal exposure time, and coarsening of the γ’ precipitates led to the simultaneous increase of the matrix channel width. The relationship between the creep rupture life and the lattice misfit of γ/γ’, the coarsening of γ’ precipitate and the precipitation of TCP phase are systematically discussed. In addition, according to the correlation between γ’ phase evolution and creep characteristics during thermal exposure, a physical model is established to predict the remaining creep life.

Application and Standard Error Analysis of the Parametric Methods for Predicting the Creep Life of Type 316LN SS

2005 ◽  
Vol 297-300 ◽  
pp. 2272-2277 ◽  
Author(s):  
Woo Gon Kim ◽  
Song Nam Yoon ◽  
Woo Seog Ryu
Keyword(s):  
Experimental Data ◽  
Standard Error ◽  
Rupture Life ◽  
Large Error ◽  
Creep Rupture ◽  
Parametric Methods ◽  
Creep Life ◽  
Statistical Process ◽  
316Ln Ss ◽  
Type 316Ln Stainless Steel

To predict the creep-rupture life of type 316LN stainless steels which are major structural components of liquid metal reactors, a number of creep-rupture data were collected through literature survey and experimental data of KAERI. Using the data, the creep-rupture life was analyzed by means of the Larson-Miller, the Orr-Sherby-Dorn and the Manson-Haferd parametric methods. Polynomial equations for predicting the creep life were obtained. In order to analyze the acceptance and use of the parametric methods, standard error values were accurately investigated by statistical process of the creep data. As for the results, the three parametric methods are found to be favorable in predicting the creep life of type 316LN stainless steel. Each method did not generate a large error in the standard error of the estimate with variations of the temperatures, but the Orr-Sherby-Dorn and the Manson-Haferd methods showed a better agreement than the Larson-Miller one. Especially, at higher the 700oC, the Manson-Haferd method conformed well to the experimental data. The reason is because the Manson-Haferd method includes two constants of ta and Ta.

Evaluation of Creep Properties of Alloy 690 Steam Generator Tubes at High Temperature Using Tube Specimen

2019 ◽  
Author(s):  
Jongmin Kim ◽  
Woogon Kim ◽  
Minchul Kim
Keyword(s):  
High Temperature ◽  
Steam Generator ◽  
Creep Test ◽  
Rupture Life ◽  
Creep Rupture ◽  
Severe Accident ◽  
High Temperature Creep ◽  
Creep Life ◽  
Temperature Creep ◽  
Alloy 690

Abstract Thermally induced steam generator (SG) tube failures caused by hot gases from a damaged reactor core can result in a containment bypass event and may lead to release of fission products to the environment. A typical severe accident scenario is a station blackout (SBO) with loss of auxiliary feedwater. Alloy 690 which has increased the Cr content has been replaced for the SG tube due to its high corrosion resistance against stress corrosion cracking (SCC). However, there is lack of research on the high temperature creep rupture and life prediction model of Alloy 690. In this study, creep test was performed to estimate the high temperature creep rupture life of Alloy 690. Based on reported creep data and creep test results of Alloy 690 in this study, creep life extrapolation was carried out using Larson-Miller Parameter (LMP), Orr-Sherby-Dorn (OSD), Manson-Haferd Parameter (MHP), and Wilshire’s approach. And a hyperbolic sine (sinh) function to determine master curves in LMP, OSD and MHP methods was used for improving the creep life estimation of Alloy 690 material.

PS44 Effect of Oxide Scale in Small Punch Creep Specimen on Creep Rupture Life

2010 ◽  
Vol 2010 (0) ◽  
pp. 143-145
Author(s):  
Masahiro KANEKO ◽  
Ken-ichi KOBAYASHI ◽  
Hideo KOYAMA
Keyword(s):  
Oxide Scale ◽  
Rupture Life ◽  
Creep Rupture ◽  
Small Punch ◽  
Creep Specimen

Study of Creep Strength for P91 Steels after Short Term Overheating above Ac3 Temperature

2013 ◽  
Vol 393 ◽  
pp. 94-101
Author(s):  
Ng Guat Peng ◽  
Badrol Ahmad ◽  
Mohd Razali Muhamad ◽  
M. Ahadlin
Keyword(s):  
High Temperature ◽  
Creep Strength ◽  
Rupture Strength ◽  
Rupture Life ◽  
Creep Rupture ◽  
Tempered Martensite ◽  
Short Term ◽  
Creep Tests ◽  
Rupture Stress ◽  
Limited Creep

Advanced ferritic steels containing 9 wt% Cr are widely used in the construction of supercritical and ultra supercritical boiler components. The microstructure of the as supplied 91 materials consists of a tempered martensite matrix, a fine dispersion of intergranular chromium rich M23C6 precipitates and intragranular carbonitrides MX particles rich in V and Nb. This steel requires post weld heat treatment (PWHT) to produce a tempered microstructure after welding to develop excellent creep strength for high temperature service. Based on past experience, situations may arise whereby the components are subjected to an accidental overshoot in temperature during PWHT. The short excursion to high temperature beyond Ac3 would have resulted in the formation of deleterious phases, for example, soft α-ferrite which has poor creep strength and hard martensite which has a low toughness. In this study, the degraded specimens with soft α ferrite as a result of cooling transformation from 900°C are proven to have a limited creep rupture life where the creep rupture strength dropped remarkably after 1000 hours. As the peak temperature increased to 950°C and 1000°C, hard and brittle martensite was formed on cooling. The creep specimens were found to exhibit better creep strength; most probably the creep behavior was improved by the tempering effect at 600°C during creep tests. Nevertheless, despite the tempering which might have improved the toughness slightly, the high temperature creep rupture stress still had dropped approximately 40%, as compared to the virgin alloys in the range of rupture time from 1,000 hours to 10,000 hours.

Tensile Creep and Creep Rupture of Continuous Strand Mat Polypropylene Composites

1995 ◽  
Vol 29 (16) ◽  
pp. 2215-2227 ◽  
Author(s):  
R. E. Little ◽  
W. J. Mitchell ◽  
P. K. Mallick
Keyword(s):  
Response Time ◽  
Creep Rupture ◽  
Tensile Creep ◽  
Test Duration ◽  
Secondary Creep ◽  
Creep Tests ◽  
Polypropylene Composites ◽  
Straight Line ◽  
Stress Levels ◽  
The Relationship

This paper describes an experimental study on the tensile creep behavior of a random continuous fiber mat reinforced polypropylene composite, commercially known as Azdel. A special experimental setup was designed and used to conduct these creep tests at 75 and 100°C with stress levels ranging from 30 to 60 percent of the tensile strength of Azdel. The test duration was 3,000 hours or the time to creep rupture response, whichever occurred first. A straight line on a semi-log plot adequately described the relationship between the imposed stress and the creep rupture response time for the range of stress levels studied. Moreover, the estimated secondary creep rate was inversely related to the observed creep rupture response time.

scholarly journals The Influence of Both Testing Environment and Fillet Radius of the Die Holder on the Rupture Life of Small Punch Creep Tests

2012 ◽  
Vol 6 (8) ◽  
pp. 925-934 ◽  
Author(s):  
Ken-ichi KOBAYASHI ◽  
Masahiro KANEKO ◽  
Hideo KOYAMA ◽  
Gavin C. STRATFORD ◽  
Masaaki TABUCHI
Keyword(s):  
Rupture Life ◽  
Creep Tests ◽  
Small Punch ◽  
Testing Environment ◽  
Fillet Radius

Creep Life Evaluations of ASME B31.1 Allowance for Variation From Normal Operations: 11 Materials

2019 ◽  
Author(s):  
Marvin J. Cohn ◽  
Ron Haupt
Keyword(s):  
Base Metal ◽  
Rupture Life ◽  
Creep Damage ◽  
Creep Rupture ◽  
Creep Life ◽  
Material Creep ◽  
Metal Creep ◽  
Life Consumption ◽  
Rupture Properties ◽  
Design Pressure

Abstract The ASME B31.1-2018 Power Piping Code (Code) paras. 102.2.4, 102.3.3, and 104.8.2 provide an allowance regarding operating above the design temperature and design pressure for short time periods. The concept of allowing occasional operation for short periods of time at higher than the design pressure or design temperature has been in the Code since 1967. These 1967 Code para. 102.2.4 limitations were based on engineering judgment that can now be quantitatively evaluated for the additional creep life consumption (creep rupture damage accumulation). This study primarily is a quantitative estimate of the permitted increased life consumption, considering minimum creep rupture properties, associated with the 2018 Code operating allowances for piping materials operating in the creep range. Eleven base metal materials are considered in this paper — low carbon steel, 1.25Cr 0.5Mo, 2.25Cr 1Mo, 9Cr 1 Mo V, Type 304 SS, Type 316 SS, Type 316L SS, Type 321 SS, Type 321H SS, Type 347 SS, and Type 347H SS. Results of this evaluation may be used to improve the ASME B31.1 Code, including a technical basis for a possible revision to para. 102.2.4. Previous studies have revealed that Grade P22 base metal creep damage is slightly more sensitive to stress than Grade P11 material creep rupture damage, and Grade P91 base metal creep damage is substantially more sensitive to stress than Grade P22 material creep rupture damage. Therefore, the allowable pressure and temperature variations result in a range of increased creep life consumption for different materials. The intent of this study was to modify the two Code allowance criteria so that the permitted increased creep life consumption (considering the minimum creep rupture properties of the material) of Allowance B is about the same amount as the increased creep life consumption result of Allowance A for the same material. Consequently, this study was performed to realign the allowable increased creep rupture life consumption of Allowance B to be approximately equivalent to the allowable increased creep life consumption of Allowance A. If the Allowance B event duration is increased from 80 hours per year to 400 hours per year, the Allowance B increased creep life consumption is slightly less than the Allowance A life consumption for each of these materials.

Sign in / Sign up

Export Citation Format

Share Document