Assessment of Creep Properties Using Small Punch Test for a 9%Cr-Mo-Co-B Power Plant Steel

The present study provides a feasible method to evaluate creep properties for a 9%Cr-Mo-Co-B power plant steel by comparing two sets of data obtained from small punch tests and conventional uniaxial creep tests. The method includes three steps: firstly, conduct a series of small punch tests and conventional creep tests in different load and temperature conditions; secondly, convert the load and central deflection data obtained from the small punch test to stress and strain data; thirdly, determinate the best fit correlation factor by comparing the two sets of data in selected creep models. It is found that two sets of data show a similar trend in stress–rupture time relation, stress–minimum strain rate relation and LMP–stress relation. The correlation factor, ksp, can effectively bridge the gap between the load in small punch test and the stress in conventional creep test. For a high-Cr martensitic heat-resistant steel named as CB2, the ksp value 1.4 can make a good prediction for rupture time, while for minimum creep rate and the Larson–Miller parameter, the ksp value 1.4 will lead a conservative prediction in the low-stress range.

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CREEP BEHAVIOR AND LIFE EVALUATION OF AGED P92 STEEL

International Journal of Modern Physics B ◽

10.1142/s0217979206041148 ◽

2006 ◽

Vol 20 (25n27) ◽

pp. 4231-4236 ◽

Cited By ~ 9

Author(s):

BUMJOON KIM ◽

BYEONGSOO LIM ◽

DONGHYUN KI

Keyword(s):

Residual Life ◽

Creep Condition ◽

Creep Tests ◽

P92 Steel ◽

Creep Properties ◽

Small Punch ◽

Punch Test ◽

Life Evaluation ◽

Long Time ◽

The Stability

Creep strength and life of material is closely related with the microstructural characteristics. Components used under creep condition for long time are unable to maintain the stability of microstructure and experience degradation of material. From this viewpoint, it is necessary for safety and residual life of power plant to investigate creep properties of specimens prepared from the material cut directly from the operating service components. The small punch test has been developed as a useful method to estimate mechanical properties because of its miniaturized specimen size. In this study, small punch creep tests were carried out to investigate the effect of aging time on creep properties using P92 steel aged from 0~12100 hrs at 600°C.

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Determination of Norton Creep Law From Small Punch Test

Volume 6A: Materials and Fabrication ◽

10.1115/pvp2014-28189 ◽

2014 ◽

Cited By ~ 1

Author(s):

Xiangsai Feng ◽

Yanfeng Qin ◽

Kai Ma ◽

Kaishu Guan

Keyword(s):

Nuclear Power ◽

Engineering Application ◽

Small Punch Test ◽

Creep Tests ◽

Small Punch ◽

Code Of Practice ◽

Punch Test ◽

Membrane Stretch ◽

Creep Curves

The present work focused on a miniature test named small punch creep test which have been employed to electric power, petro-chemical, nuclear power and other fields widely in the last three decades. Under normal circumstances, engineering application pay more closer attention to the Norton creep law. To determine the Norton creep law, at least three creep curves were needed by traditional method, it’s time consuming and uneconomic. In present paper, the small punch creep tests were carried out following the CEN code of practice. Based on Chakrabarty’s membrane stretch model and Norton power law, the results of small punch creep tests and finite element method have been compared and discussed. A completely novel and economical approach was proposed to determine the parameters of Norton creep law more accurately and conveniently. The results show that, if scopes of parameters known, the Norton creep law could be determined accurately even from one creep curve only.

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Estimation of Anisotropy of Creep Properties in Al and Mg Alloys by Means of Small Punch Test

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.734.137 ◽

2017 ◽

Vol 734 ◽

pp. 137-143

Author(s):

Ferdinand Dobeš ◽

Petr Dymáček

Keyword(s):

Elevated Temperatures ◽

Hot Extrusion ◽

Orientation Dependence ◽

Small Punch Test ◽

Creep Properties ◽

Small Punch ◽

Punch Test ◽

Angular Pressing ◽

Planar Orientation

Small punch test was used to evaluate the properties of light alloys in various directions. Three different materials were studied: (i) magnesium alloy WE54 prepared by a powder metallurgical route with final hot extrusion, (ii) aluminium alloy reinforced with 20 vol. % of Saffil fibres with planar orientation, and (iii) Al-Al4C3 composite prepared by mechanical alloying and subjected to equal channel angular pressing as a final step. Tests were performed under constant force at elevated temperatures. The observed orientation dependence of creep properties is strongly material dependent. The results confirm the feasibility of the small punch test for determination of anisotropy of mechanical properties.

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Determination of Creep Properties from Small Punch Test with Reverse Algorithm

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.734.212 ◽

2017 ◽

Vol 734 ◽

pp. 212-236 ◽

Cited By ~ 3

Author(s):

Ying Zhi Li ◽

Paul Stevens ◽

Jin Feng Geng ◽

Dong Fang Ma ◽

Liang Xu

Keyword(s):

Electric Power ◽

Power Plants ◽

Small Punch Test ◽

Plastic Properties ◽

Creep Properties ◽

Small Punch ◽

Material Parameters ◽

Code Of Practice ◽

Punch Test ◽

Acceptable Method

In the early 1980’s, the small punch technique was developed in USA and Japan. This technique has been applied to nuclear reactors, electric power plants for safety assessments. European researchers have carried out the pioneer work on SP creep testing in the 1990’s. European Code of Practice (CoP) documents have become available in 2006, which provides a guide line to perform small punch tests for metallic materials, and introduces methods for estimation of tensile properties, fracture toughness and creep properties. Since then several conferences and symposiums have been held to exchange ideas and experiences, and several efforts have been made to improve the approaches for interpreting the material properties from test results. However, due to the complexity of the small punch test itself and lack of systematic test data for verification, especially in the creep region, up to now there is no common acceptable method to interpret creep properties. This paper discusses some of the problems commonly encountered in the small punch creep test (SPCT) analysis, such as the uniqueness in reverse creep analysis for identification of material parameters, how to consider effects of large deformation and strain hardening, how to separate deflection into a part caused by loading and a part caused by creep, and how to estimate the elastic-plastic properties of a material in the creep temperature region. Based on these considerations, several existing approaches for interpreting creep properties have been re-evaluated. In addition, a software package, based on the optimization toolbox of Matlab has been developed for identification of material parameters automatically. Verifications are performed by checking the agreement between properties derived by small punch test and uni-axial tests. Discussions on problems of existing approaches and how to improve them further, are described in the paper. Experimental data are provided by JRC Petten, Netherlands, and Henan Electric Power Research Institute, China. Recently a working group led by JRC Petten is engaged in upgrading the CoP to a European standard. It is expected that in the future more data will become available for further verification.

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Identification of Creep Parameters of P91 by Small Punch Test

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.529.439 ◽

2014 ◽

Vol 529 ◽

pp. 439-443 ◽

Cited By ~ 1

Author(s):

Jin Feng Geng ◽

Hong Sheng Cai ◽

Dong Fang Ma ◽

Xiang Sai Feng ◽

Kai Shu Guan

Keyword(s):

Creep Test ◽

Practical Method ◽

The Other ◽

Experimental Curve ◽

Small Punch Test ◽

Creep Properties ◽

Small Punch ◽

Punch Test ◽

Four Levels ◽

Small Punch Creep Test

Four levels of load were performed on different small punch creep specimens in order to investigate the creep properties of the P91 by small punch creep test at 600°C. A practical method was proposed to identification of creep parameters of P91 by comparison of experimental curves and simulate curves from only one experimental curve. The other three experimental curves was performed to verify the practical method.

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On the interpretation of results from small punch creep tests

The Journal of Strain Analysis for Engineering Design ◽

10.1243/03093247jsa592 ◽

2010 ◽

Vol 45 (3) ◽

pp. 141-164 ◽

Cited By ~ 44

Author(s):

T H Hyde ◽

M Stoyanov ◽

W Sun ◽

C J Hyde

Keyword(s):

Finite Element ◽

Creep Behaviour ◽

Test Material ◽

Complex Nature ◽

Small Punch Test ◽

Creep Tests ◽

Linear Processes ◽

Small Punch ◽

Punch Test ◽

Uniaxial Creep

The small punch creep testing method is highly complex and involves interactions between a number of non-linear processes. The deformed shapes that are produced from such tests are related to the punch and specimen dimensions and to the elastic, plastic, and creep behaviour of the test material, under contact and large deformation conditions, at elevated temperature. Owing to its complex nature, it is difficult to interpret the small punch test creep data in relation to the corresponding uniaxial creep behaviour of the material. One of the aims of this paper is to identify the important characteristics of the creep deformation resulting from ‘localized’ deformations and from the ‘overall’ deformation of the specimen. Following this, the results of approximate analytical and detailed finite element analyses of small punch tests are investigated. It is shown that the regions of the uniaxial creep test curves dominated by primary, secondary, and tertiary creep are not those that are immediately apparent from the displacement versus time records produced during a small punch test. On the basis of the interpretation of the finite element results presented, a method based on a reference stress approach is proposed for interpreting the results of small punch test experimental data. Future work planned for the interpretation of small punch tests data is briefly addressed.

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Determination of creep properties from small punch test using experimental correlation

Ubiquity Proceedings ◽

10.5334/uproc.17 ◽

2018 ◽

Vol 1 (S1) ◽

pp. 17

Author(s):

P. Dymáček ◽

F. Dobeš ◽

Y. Li ◽

S. Holmström ◽

P. Stevens

Keyword(s):

Small Punch Test ◽

Creep Properties ◽

Small Punch ◽

Punch Test ◽

Experimental Correlation

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Determination of Creep Properties From Small Punch Test

Volume 3: Design and Analysis ◽

10.1115/pvp2008-61437 ◽

2008 ◽

Cited By ~ 12

Author(s):

Yingzhi Li ◽

Roman Sˇturm

Keyword(s):

Power Plants ◽

Research Work ◽

Small Punch Test ◽

Creep Properties ◽

Small Punch ◽

Code Of Practice ◽

Punch Test ◽

Starting Point ◽

European Code

The small punch test is one of the techniques, which can directly assess the current material properties of components on situ. The main advantages of this method are that only small amount of material is needed and no repair is required afterwards. In addition, the test itself is rather simple to perform. Since early 1980’s, the technique has been developed and applied to nuclear reactors, electric power plants for safety assessment. European researchers have carried out the pioneer work on small punch testing at the creep region. Recently the European Code of Practice documents are available for both high and low temperature properties, which summarizes the international experiences in last 20 years and provides a guide line to perform small punch test for metallic materials. This paper gives an overview of the research work on determination of creep properties from small punch test. Verification is performed by comparison of creep properties derived by small punch test and uni-axial tests. An agreement is found and shows that small punch test is able to predict reasonable creep properties of materials. Considerations how to improve the approach are also addressed. Further work is needed as available tests are still limited. This paper makes a starting point that others can improve further.

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