Effects of test specimen geometry on creep behaviour of 12Cr steel in miniaturised disc bend tests

Ule, B.; Šturm, Roman; Leskovšek, Vojteh

doi:10.1179/026708303225009463

Cited by 13 publications

(22 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Had they compared their results with the Code of Practice methodology this work could have been an extremely useful contribution towards validation. Some concern has been raised related to the choice of the large punch size of 2.5mm with a 4mm receiving hole although this is considered as the limit as the clearance should be substantially greater than the disc thickness otherwise the test would approach the conditions for a shear test and not a small punch bulge test according to Ule et al (2003). Also disc thicknesses have not always been 0.5mm, Madia et al (2013) used 0.43mm and Turba et al (2012) used 0.47mm.…”

Section: Figure1 Geometry Of the Sp Test Installation According To Thmentioning

confidence: 99%

A Renaissance in the Use of the Small Punch Testing Technique

Hurst

Matocha

2015

Volume 1B: Codes and Standards

View full text Add to dashboard Cite

The underlying purpose of this paper is to evaluate whether the CEN CWA 15627 “Small Punch Test Method for Metallic Materials” first published in 2006 has indeed succeeded in providing a stimulus for a wider implementation of the small punch test technique in industrial applications throughout Europe and indeed worldwide. A wealth of research progress has been apparent, as strongly evidenced in three dedicated SSTT (Small Specimen Testing Techniques) conferences held in Europe over the last five years, but also in the wider literature. In particular it is important to mention the recent publication of a Japanese standard and the announcement of parallel progress in China. The present paper concentrates on progress within Europe from the launch of the Code to the present day. In particular attention is focused on the need for industrial acceptance of the test methodology and methods for evaluating the results. Some scepticism still seems to prevail within sectors of the conventional power generation industry, an industry which can potentially benefit most from successful remanent lifetime extension tools of which small punch testing can be considered as a prime candidate. In spite of this, it is demonstrated that a major proportion of the Small Punch testing research of the last decade has been carried out on power plant steels. Meanwhile it is shown that there is evidence that the original remit of the methodology in assessing the integrity of irradiated nuclear plant remains active, new interest is developing for aerospace and next generation nuclear applications enhancing further the credibility of the Code.

show abstract

Section: Figure1 Geometry Of the Sp Test Installation According To Thmentioning

confidence: 99%

A Renaissance in the Use of the Small Punch Testing Technique

Hurst

Matocha

2015

Volume 1B: Codes and Standards

View full text Add to dashboard Cite

show abstract

“…7 it is clear that at some disc thickness (between ∼ 0.48 mm and ∼ 0.50 mm) the constant C 1 becomes almost independent on the disc thickness. Since the maximum disc thickness is limited by the condition θ 0 ≤ Cl [15], and thus it cannot exceed 0.50 mm, the optimum disc thickness for the actual small-punch device is, therefore, strictly determined.…”

Section: Resultsmentioning

confidence: 99%

“…However, the duration of the creep process is influenced by the thickness of the disc as well as by the ratio between the disc thickness and the die clearance. Therefore, the condition θ 0 ≤ Cl (where θ 0 is the disc thickness and Cl is the so-called die clearance) has to be fulfilled in order to measure the creep properties correctly [15]. A comparison between the static disc loading P during the small-punch creep test and the tensile stress σ during a conventional, uniaxial, tensile creep test confirmed the most likely linear dependence between σ/P and 1/θ 0 described by the following relation [16]:…”

Section: Introductionmentioning

confidence: 99%

An improved, stress-dependent, energy-barrier model for the creep of 9Cr-1Mo-0.2V steel under disc-bend loading

Nagode¹,

Ule²,

Kosec³

et al. 2010

Self Cite

View full text Add to dashboard Cite

In this paper we describe the creep behaviour of 9Cr-1Mo-0.2V steel under disc-bend loading, also known as the small-punch method. An improved power-law, stress-dependent, energy-barrier model was used to describe the creep behaviour of 9Cr-1Mo-0.2V steel because the characteristics of this steel cannot be accurately described using a simple, Arrhenius-type power law. A good correlation between the calculated values from the improved model and the experimental data was obtained for discs of different thickness, i.e., 0.50 mm, 0.47 mm and 0.44 mm. We found that the optimum disc thickness for our small-punch device was 0.50 mm. The stress-dependent, apparent activation energy of creep for a disc thickness of 0.50 mm decreased from ∼ 543 kJ mol

show abstract

“…To prevent speckle pattern flaking due to excessive strains, the discs are prebulged into "sombrero" shapes at the same temperature and to the same load used in the subsequent creep test. Such an approach was shown by Ule et al [10] to have no effect on the creep curve development in terms of rupture time and minimum creep rates. Following the prebulging, the load is removed, and the preformed disc is removed for speckle patterning according to the procedure outlined in Section 2.3.…”

Section: Preformingmentioning

confidence: 99%

“…Despite the wide-scale applications of SPCT, the technique involves several challenges that are not normally associated with traditional testing including sensitivities to: geometrical uncertainties in the experimental setup such as the indenter size and eccentricity from the disc centre [8]; upper die clamping conditions [9]; differences in disc specimen thickness with a direct effect on creep rupture times [10]; atmospheric conditions [11]; oxidation [12] as well as friction between punch components and the disc [13].…”

Section: Introductionmentioning

confidence: 99%

An Experimental Approach to the Application of Digital Image Correlation to Small Punch Creep Testing

2021

View full text Add to dashboard Cite

Deterioration assessment of materials is essential to the continued effective operation of critical components operating, at high temperatures and stresses, in thermal power plants. Within progressive inspection strategies, small punch creep testing (SPCT) presents an effective method for establishing the degree of creep exhaustion of in-service power engineering alloys on account of the small volume of material required (Ø8 mm × 0.5 mm discs). These tests make the application of complex strain fields, analogous to the strain field experienced by the service components, possible. In addition, this work explores the application of a noncontact digital image correlation (DIC) method to the full-field measurement of strains which is not possible through traditional extensometry. The accelerated SPCT tests were performed on 12 % Cr ex-service steels subjected to 600 °C. Experimental methodologies and challenges associated with ex situ DIC-SPCT are discussed including equipment and parameter selection, speckle pattern application, preforming requirements and loading method. It is shown that the developed DIC technique using a stereo microscope, airbrushed speckle patterns, sombrero-preformed discs and interrupted tests can be used to compare surface strain development in various aged forms of the ex-service steel. Such an approach is valuable to understanding strain development in small punch tests and to assist in the comparative damage assessment of ex-service power plant materials.

show abstract

Effects of test specimen geometry on creep behaviour of 12Cr steel in miniaturised disc bend tests

Cited by 13 publications

References 9 publications

A Renaissance in the Use of the Small Punch Testing Technique

A Renaissance in the Use of the Small Punch Testing Technique

An improved, stress-dependent, energy-barrier model for the creep of 9Cr-1Mo-0.2V steel under disc-bend loading

An Experimental Approach to the Application of Digital Image Correlation to Small Punch Creep Testing

Contact Info

Product

Resources

About