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.

A New Approach of Reliability Design For Creep Rupture Property

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
Jie Zhao ◽  
Dong-ming Li ◽  
Yuan-yuan Fang ◽  
Shi-jie Zhu
Keyword(s):  
Parametric Method ◽  
Stress Rupture ◽  
Creep Rupture ◽  
Parameter Method ◽  
Heat Resistant Steel ◽  
Reliability Design ◽  
Z Parameter ◽  
Rupture Data ◽  
Temperature Parameter ◽  
Temperature Time

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 the 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 the 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-time temperature parameter-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 the reliability concept into creep rupture property design.

Reliability Design for Creep Rupture Strength of 2.25Cr-1Mo Steel

2011 ◽  
Vol 675-677 ◽  
pp. 507-510
Author(s):  
Ji Bin Pei ◽  
Yun Feng Zhao ◽  
Dong Ming Li ◽  
Jie Zhao ◽  
Lai Wang
Keyword(s):  
Rupture Strength ◽  
Creep Rupture ◽  
Parameter Method ◽  
Allowable Stress ◽  
Creep Rupture Strength ◽  
Reliability Design ◽  
Design Life ◽  
Real Distribution ◽  
Z Parameter ◽  
Rupture Data

A statistical analysis of creep rupture data for 2.25Cr-1Mo steel was performed. The scattering of creep rupture data was represented by Z-parameter method based on Manson-Haferd method. With the application of Z-parameter, reliability design for allowable stress of creep rupture strength was carried out according to design life. The higher the value of confidence level, the lower the allowable stress. In comparison with safety factor method and minimum rupture strength method, it can be seen that reliability design based on Z-parameter is more agree with experimental data than other methods. Reliability design provides more precise results by considering the real distribution of creep rupture property and provides more flexible choice for design due to the need of safety and economy.

Allowable Stress Design of Rupture Strength Based on Confidence Level of 9Cr-1Mo Steel

2012 ◽  
Vol 155-156 ◽  
pp. 1107-1111
Author(s):  
Ji Bin Pei ◽  
Yun Feng Zhao ◽  
Shao Ping Yu ◽  
Jie Zhao
Keyword(s):  
Safety Factor ◽  
Rupture Strength ◽  
Creep Rupture ◽  
Parameter Method ◽  
Allowable Stress ◽  
Reliability Design ◽  
Factor Method ◽  
Z Parameter ◽  
Rupture Data ◽  
Allowable Stress Design

The scattering of creep rupture data was represented by Z-parameter method based on Larson-Miller method. It was verified that the values of Z were supported by normal distribution. After obtained the distribution characteristics of creep rupture data using Z-parameter, reliability design for rupture allowable stress was carried out according to design life. Safety factor method is used for safety guarantee in conventional rupture allowable stress design and minimum rupture strength method is used in some standard. In comparison with safety factor method and minimum rupture strength method, it can be seen that reliability design based on Z-parameter is more agree with experimental data than other methods. Reliability design provides more precise results by considering the real distribution of creep rupture property and provides more flexible choice for design due to the need of safety and economy.

Reliability Design for Allowable Stress of Creep Rupture Strength of 4Cr25Ni35 Steel

2012 ◽  
Vol 476-478 ◽  
pp. 2552-2555
Author(s):  
Ji Bin Pei ◽  
Yun Feng Zhao ◽  
Shao Ping Yu ◽  
Jie Zhao
Keyword(s):  
Experimental Data ◽  
Statistical Analysis ◽  
Rupture Strength ◽  
Creep Rupture ◽  
Parameter Method ◽  
Allowable Stress ◽  
Creep Rupture Strength ◽  
Reliability Design ◽  
Z Parameter ◽  
Rupture Data

Creep rupture data plays vital role in life prediction and safety assessment of high temperature components. In order to describe the scattering of the data, a statistical analysis of creep rupture data for 4Cr25Ni35 steel was performed by Z-parameter method. With the application of Z-parameter, reliability design for allowable stress of creep rupture strength was carried out according to design life. It is found that Manson-Haferd method appears better correlation results with experimental data. Statistical analysis shows that the scattering of Z-parameter for 4Cr25Ni35 steel is supported by normal distribution. Compared with safety factor method, the method based on Z-parameter can perform reliability design for allowable stress of creep rupture strength by considering the dispersibility of the rupture data. Reliability design based on Z-parameter is more agree with experimental data.

Design of Rupture Strength Based on Confidence Level of HK40 Steel

2012 ◽  
Vol 499 ◽  
pp. 123-126
Author(s):  
Ji Bin Pei ◽  
Yun Feng Zhao ◽  
Shao Ping Yu ◽  
Jie Zhao
Keyword(s):  
Rupture Strength ◽  
Statistical Processing ◽  
Creep Rupture ◽  
Parameter Method ◽  
Allowable Stress ◽  
Creep Rupture Strength ◽  
Reliability Design ◽  
Strength Based ◽  
Z Parameter ◽  
High Temperature Components

The strength of high temperature components is designed according to creep rupture strength. A statistical processing of creep rupture data of HK40 steel was performed by Z-parameter method based on Larson-Miller method. The data has been studied to evaluate the distribution under different temperature and stress. And the distribution of Z-parameter was investigated. With the application of Z-parameter, reliability design for allowable stress of creep rupture strength was carried out according to design life. The results show that the distribution of Z-parameter is supported by normal distribution. In comparison with allowable stress designed by conventional safety factor method, reliability design based on Z-parameter is more agree with experimental data.

Reliability Assessment of Creep Rupture Life for Gr.91 Steel by an Interference Model

2011 ◽  
Author(s):  
Woo-Gon Kim ◽  
Jae-Young Park ◽  
Song-Nan Yin ◽  
Dae-Whan Kim ◽  
Ji-Yeon Park ◽  
...  
Keyword(s):  
Normal Distribution ◽  
Rupture Life ◽  
Reliability Assessment ◽  
Creep Rupture ◽  
Interference Model ◽  
Service Temperature ◽  
Z Parameter ◽  
Rupture Data ◽  
Fluctuation Amplitude ◽  
Higher Temperature

This paper focuses on reliability assessment of creep rupture life under the service conditions at high temperatures and stresses for Gr. 91 steel which is considered as one of the prime structural materials for next-generation nuclear reactors. An interference model based on Z parameter, which is considered for the fluctuations of both service temperature and stress besides the scattering of rupture data, was analyzed and used to assess the reliability on creep rupture life of Gr. 91 steel. The scattering distribution of the creep rupture data of the Gr. 91 steel was investigated by using the Z parameter. It appeared that the Z parameter of creep rupture data for Gr.91 steel exhibited normal distribution. Using the normal distribution, a Monte-Carlo simulation (MCS) was carried out to generate a number of random variables for Zs and Zcr, and the reliability of the creep rupture life under the fluctuations of service temperature and stress conditions was estimated by using the interference model. It showed that the value of reliability decreased with increasing service time. Higher temperature caused the trend of faster deterioration. The value of reliability decreased rapidly at higher temperature fluctuation amplitude, and the reliability decreased as the scattering of the creep rupture data became serious.

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.

Comparison of Parameter Methods for Extrapolating High-Temperature Data

1959 ◽  
Vol 81 (4) ◽  
pp. 629-643 ◽  
Author(s):  
R. M. Goldhoff
Keyword(s):  
High Temperature ◽  
Stress Rupture ◽  
High Temperature Stress ◽  
Parameter Method ◽  
Time Data ◽  
Rupture Data ◽  
High Temperature Data ◽  
Long Time ◽  
Nimonic 80A ◽  
Short Time

The use of the controversial and contradictory parameter techniques in correlation of high-temperature stress-rupture data is discussed. They are treated with a view toward their application in extrapolating short-time data to predict working stresses in serviceable heat-resistant alloys. Three parameter methods are compared on a statistical basis for their ability to reproduce the isothermal data on which they are based and in particular the longest time data currently available and usable for this purpose. Comparisons are further made with long-time extrapolations based on direct plotting of test data. The materials chosen for evaluation are alloys S-590, A-286, Nimonic 80A, and 1Cr-1Mo-1/4V steel. It is shown that prediction of long-time working stresses using parameter techniques will generally give better results than can be obtained from long extrapolations on double logarithmic plots. Among the parameters themselves, the Manson-Haferd linear parameter method gave the most reliable extrapolations. However, the results obtained using the Larson-Miller method may be improved considerably if the proper constant is selected for each set of data rather than using C = 20 for all data. For reliable extrapolations all methods require data from tests up to 1000 hr and covering adequate ranges of stress and temperature.

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.

Z-Parameter Method for Life Prediction in Low Carbon Steels

2005 ◽  
Vol 297-300 ◽  
pp. 1758-1763 ◽  
Author(s):  
Shuang Qi Han ◽  
Jie Zhao ◽  
Lai Wang ◽  
Hong Bo Gao
Keyword(s):  
Life Prediction ◽  
Master Curve ◽  
Carbon Steels ◽  
Parameter Method ◽  
Low Carbon ◽  
Low Carbon Steels ◽  
Linear Relationships ◽  
Z Parameter ◽  
Rupture Data ◽  
Rupture Properties

In this paper, a Z-parameter method is proposed to relate creep rupture data and microstructure deterioration of three low carbon steels: Cr5Mo, 12Cr1MoV and 20 steels. A new analytic expression of the Larson-Miller parameter verse stress is supposed as: P =Z + C1 lgσ + C2 σ, where C1 and C2 are constants which determine the shape of the curves and related to materials, and the value of parameter Z represents the magnitude deviated from the master curve which corresponds with the deterioration in rupture properties. As the deterioration in rupture properties closely connects with the degradation of microstructure, namely the spheroidization of carbides in pearlite style steel, a linear relationships have been found between the value of Z-parameter and the level of spheroidization E which can be expressed as: Z = a1 + a2 E.

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