Multiaxial Stress Rupture Testing and Compendium of Data for Creep Resisting Steels

1982 ◽  
Vol 104 (4) ◽  
pp. 291-296 ◽  
Author(s):  
R. J. Browne ◽  
D. Lonsdale ◽  
P. E. J. Flewitt
Keyword(s):  
Stress Rupture ◽  
Creep Rupture ◽  
Estimation Methods ◽  
Multiaxial Stress ◽  
Life Estimation ◽  
Uniaxial Creep ◽  
Rupture Data ◽  
Stress Rupture Testing ◽  
Present Life ◽  
Rupture Criterion

Recently, there has been an increasing need for more accurate methods of predicting the life of components operating in the creep range. Although many such components are invariably subject to multiaxial stress systems, present life estimation methods utilize available uniaxial creep rupture data via a representative stress for the component. This stress is usually empirically derived and in many cases leads to undue conservatism in life estimates because no account is taken of the creep and rupture response of the material to multiaxial stresses. This paper reviews the various multiaxial stress rupture test techniques which have been employed to determine the multiaxial stress rupture criterion. The multiaxial stress rupture data available in the literature for some commonly used creep resisting steels are compiled and discussed.

A New Approach of Reliability Design for Creep Rupture Property

2009 ◽  
Author(s):  
Jie Zhao ◽  
Dong-ming Li ◽  
Yuan-yuan Fang ◽  
Shi-jie Zhu
Keyword(s):  
Parametric Method ◽  
Stress Rupture ◽  
Creep Rupture ◽  
Parameter Method ◽  
Reliability Design ◽  
Safety Coefficient ◽  
Real Distribution ◽  
Z Parameter ◽  
Rupture Data ◽  
Temperature Time

It has been noted that the use of safety coefficient can deal with uncertainties existed in practical structures, while reliability concept provides more precise results by considering the real distribution of creep rupture property. Generally, creep rupture data of a heat-resistant steel can be compressed into a narrow band by using a temperature-time parametric method such as Larson-Miller or Manson-Haferd method. In order to describe the scattering of the data, the current paper proposes a “Z parameter” method to represent the magnitude of the deviation of the rupture data to master curve. Statistical analysis shows that the scattering of Z parameter for several types of steels is supported by normal distribution. Using this method, it is possible to achieve unified analysis of the creep rupture data in various temperature and stress conditions. Stress-TTP-Reliability curves (σ-TTP-R curves), Stress-Rupture time-Reliability curves (σ-tr-R curves) and Allowable stress-Temperature-Reliability curves ([σ]-T-R curves) are proposed which could embrace reliability concept into creep rupture property design.

Creep rupture of notched bars

1978 ◽  
Vol 360 (1701) ◽  
pp. 243-264 ◽  
Keyword(s):  
Damage Mechanics ◽  
Axial Stress ◽  
Stress Rupture ◽  
Continuum Damage Mechanics ◽  
Constant Load ◽  
Creep Rupture ◽  
Structural Behaviour ◽  
British Standard ◽  
Rupture Criterion ◽  
Circular Notch

The creep rupture of circumferentially notched, circular tension bars which are subjected to constant load for long periods at constant tem ¬ perature is studied by the approximate calculation of stress and damage histories which result from tertiary creep. Stationary-state creep solutions which have been previously obtained by Hayhurst & Henderson (1977) are used in a continuum damage mechanics study of rupture at the minimum sections of circular (Bridgman 1952) and British Standard notched specimens (B.S. no. 3500, 1969). Notch strengthening and weakening are explained in terms of the multi-axial stress rupture criterion satisfied by the material. It is shown how the circular notch may be used as a materials test and that the British Standard notch is a good means of assessing the sensitivity of structural behaviour to the multi-axial stress rupture criterion of the material.

scholarly journals Small Two-Bar Specimen Creep Testing of Grade P91 Steel at 650°C

2016 ◽  
Vol 35 (3) ◽  
pp. 243-252
Author(s):  
Balhassn S. M. Ali ◽  
Tom H. Hyde ◽  
Wei Sun
Keyword(s):  
Strain Rate ◽  
Creep Strain ◽  
Test Data ◽  
Creep Test ◽  
Uniaxial Stress ◽  
Creep Rupture ◽  
Creep Strain Rate ◽  
P91 Steel ◽  
Uniaxial Creep ◽  
Rupture Data

AbstractCommonly used small creep specimen types, such as ring and impression creep specimens, are capable of providing minimum creep strain rate data from small volumes of material. However, these test types are unable to provide the creep rupture data. In this paper the recently developed two-bar specimen type, which can be used to obtain minimum creep strain rate and creep rupture creep data from small volumes of material, is described. Conversion relationships are used to convert (i) the applied load to the equivalent uniaxial stress, and (ii) the load line deformation rate to the equivalent uniaxial creep strain rate. The effects of the specimen dimension ratios on the conversion factors are also discussed in this paper. This paper also shows comparisons between two-bar specimen creep test data and the corresponding uniaxial creep test data, for grade P91 steel at 650°C.

Methodology for selecting creep tests to establish multiaxial stress rupture criterion

1992 ◽  
Vol 8 (12) ◽  
pp. 1141-1144 ◽  
Author(s):  
D. Lonsdale ◽  
R. J. Browne ◽  
P. E. J. Flewitt
Keyword(s):  
Stress Rupture ◽  
Multiaxial Stress ◽  
Creep Tests ◽  
Rupture Criterion

Creep rupture of the Andrade shear disk

1976 ◽  
Vol 349 (1658) ◽  
pp. 369-382 ◽  
Keyword(s):  
Large Deformations ◽  
Stress Rupture ◽  
Creep Rupture ◽  
Large Strains ◽  
Test Results ◽  
Multiaxial Stress

The use of the Andrade shear disk as a means of determining the multiaxial stress rupture criteria for metals is discussed. Test results are reported for disks machined from materials which undergo both small and large strains to failure. The rupture behaviour of the disks which undergo large deformations is analysed. Statements are made concerning the use of conventional constitutive and damage laws for large deformations.

Prediction of Long-Term Creep Rupture Life of Grade 122 Steel by Multiregion Analysis

2014 ◽  
Vol 137 (2) ◽  
Author(s):  
K. Maruyama ◽  
J. Nakamura ◽  
K. Yoshimi
Keyword(s):  
Rupture Life ◽  
Creep Rupture ◽  
Data Sets ◽  
Data Set ◽  
Life Estimation ◽  
Rupture Data ◽  
Temperature Dependences ◽  
Temperature Parameter ◽  
Term Creep

Conventional time-temperature-parameter (TTP) methods often overestimate long-term rupture life of creep strength enhanced ferritic steels. Decrease in activation energy Q for rupture life in long-term creep is the cause of the overestimation, since the TTP methods cannot deal with the change in Q. Creep rupture data of a heat of Gr.122 steel (up to 26,200 h) were divided into several data sets so that Q was unique in each divided data set. Then a TTP method was applied to each divided data set for rupture life prediction. This is the procedure of multiregion analysis of creep rupture data. The predicted rupture lives have been reported in literature. Long-term rupture lives (up to 51,400 h) of the same heat of the steel have been published in 2013. The multiregion analysis of creep rupture life can predict properly the long-term lives reported. Stress and temperature dependences of rupture life show similar behavior among different heats. Therefore, database on results of the multiregion analyses of various heats of the steel is helpful for rupture life estimation of another heat.

Evaluation of Stress Rupture Factors for Grade 91 Weldments

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Kazuhiro Kimura ◽  
Masatsugu Yaguchi
Keyword(s):  
Base Metal ◽  
Rupture Strength ◽  
Stress Rupture ◽  
Creep Rupture ◽  
Creep Rupture Strength ◽  
Premature Failure ◽  
Rupture Data ◽  
Grade 91 ◽  
Grade 91 Steel

Abstract Stress rupture factors and weld strength reduction factors for Grade 91 steel weldments in the codes and literatures have been reviewed. Stress rupture factors for weld metals proposed for code case N-47 in the mid 1980's was defined as a ratio of average rupture strength of the deposited filler metal to the average rupture strength of the base metal. Remarkable drop in creep rupture strength of weldments is significant issue of Grade 91, especially in the low-stress and long-term regime. A premature failure of Grade 91 steel weldments in the long-term, however, is caused by type IV failure which takes place in the fine grain heat affected zone (FG-HAZ), rather than fracture in the deposited weld metal. The stress rupture factor of the Grade 91 steel, therefore, was based on the creep rupture strength of cross weld test specimens. Creep rupture data of Grade 91 steel weldments reported in the publication of ASME STP-PT-077 were integrated with the creep rupture data collected in Japan and used for this study. Time- and temperature-dependent stress rupture factors for Grade 91 steel have been evaluated based on the consolidated database as a ratio of average creep rupture strength of cross weld test specimen to the average creep rupture strength of base metal.

A Simplified Approach to the Effect of Specimen Size on the Creep Rupture of Cross Weld Samples

1982 ◽  
Vol 104 (1) ◽  
pp. 36-40 ◽  
Author(s):  
J. A. Williams
Keyword(s):  
Failure Time ◽  
Stress Rupture ◽  
Limit Load ◽  
Parent Material ◽  
Creep Rupture ◽  
Creep Data ◽  
Simplified Approach ◽  
Reference Stress ◽  
Failure Location ◽  
Stress Rupture Testing

Various methods are available to assess the performance of welded joints under creep conditions. One approach uses the creep rupture testing of cross weld geometries in uniaxial tension. This paper examines an idealized model of a cross weld specimen where the weld metal is weaker than the parent material. The analysis, which is developed from published work on brazed and soldered joints, characterizes the limit load of the specimen as a function of the weld thickness:specimen diameter ratio and the yield strengths of both materials. The limit load is then used to define a creep reference stress which may be applied to uniaxial data. The predictions of the failure location and failure time are compared with cross weld creep data generated within the CEGB as no suitable data were found in the general literature. Finally, the model is used to postulate a size or weld thickness:specimen diameter effect on stress rupture testing of cross weld geometries.

Sign in / Sign up

Export Citation Format

Share Document