A Renaissance in the Use of the Small Punch Testing Technique

Abstract

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.

Mechanical characterization of PM aluminum composites by small punch test

“…It should be noted that another offset t/10 method is also found in the open literature [4,7].For the present work only two definitions P Y MAO* and P Y t/100 will be analyzed due to these respective load represent the beginning of plasticity [4]. Other authors assume that massive yielding is the right criterion to define the fully plastic behavior [7,12], that is the case of t/10 method. It is also noted that the effect of thickness variation has to be taken into account very carefully because small variations have strong incidence in load change in SPT curve.…”

“…On the one hand, there is no big difference in respect to choose method for the case of F12. On the other hand, the physical meaning of P Y is still under debate [4,7,10,12] . A selection of P Y methodological criteria should be complemented with more detailed analyze of plasticity development across the whole specimen thickness.…”

“…However this intersection P Y MAO falls out from P vs.  curve. Following a similar procedure suggested by the European Code [12] a vertical projection from P Y MAO was made to define a P Y MAO* [4].GARCIA et al [6] proposed an offset method defined by a parallel line to regime I shifted in displacement t/100. The intersection is called P Y t/100 is equivalent to engineering definition of 0.2 % strain to calculate the yield stress.…”

The role of small specimen creep testing within a life assessment framework for high temperature power plant

“…[5]. Part B is focused on the test rig, test procedure, test specimen preparation, interpretation of results and methods for deriving the yield strength, the ductile-to-brittle transition temperature (DBTT) and the fracture toughness from SPCT [5,23]. Hurst and Matocha published a critical review on the CEN CWA 15627 also suggesting some potential improvements of the code [23].…”

“…The European CEN CWA 15627 [5], last updated in 2007, has been accepted as a first incentive for industrial applications all through the world, even if it is far away to be a standard and certainly needs to be improved [23]. [5].…”