Considerations for the accreditation of small punch creep testing

A.J Jones,M.R Bache

doi:10.5334/uproc.26

Abstract

Efforts to extend a pre-existing European Code of Practice (CoP) covering small punch creep and tensile testing into a full International standard procedure are progressing. Swansea Materials Research & Testing Ltd, in collaboration with the academic team based at Swansea University, have been proactive in anticipating some of the key recommendations from the ECISS TC 1010/WG 1 with a view to gaining accreditation for an extensive suite of small punch test equipment. Here, comparisons between the miniaturised form of small punch creep testing will be made to the expectations for calibration and measurement laid down by existing standards for creep testing of conventional scale specimens. In particular, the calibration requirements relating to load, displacement, alignment and temperature measurement will be addressed. With test reproducibility at the forefront of our attention, recent modifications to test rigs to control load application and validation exercises to define small punch temperature distribution will be described. Ultimately, the need to develop an uncertainty budget for small punch creep testing will be highlighted.

Highlights

The suite of small punch test machines currently employed for creep evaluations at Swansea Materials Research & Testing Ltd (SMaRT) has been fashioned over the previous quarter century to address a wide range of assessment requirements
Grounded on local best practice, Swansea based academics contributed to the establishment of the original European Code of Practice [1] in small punch testing
By comparing to the best practice employed for conventional scale creep testing under tension, the authors hope to initiate a debate relating to the requirements of research and commercial test laboratories alike in preparation for accreditation against the forthcoming European standard for small punch creep testing

Summary

Introduction

The suite of small punch test machines currently employed for creep evaluations at Swansea Materials Research & Testing Ltd (SMaRT) has been fashioned over the previous quarter century to address a wide range of assessment requirements. Grounded on local best practice, Swansea based academics contributed to the establishment of the original European Code of Practice [1] in small punch testing. The fundamental requirements of creep testing were applied to the small punch technique, in particular the need for thermal and mechanical stability over long time periods, exceeding thousands of hours on test. A rigorous assessment of typical small punch test equipment is required in anticipation of a new European test standard to be developed through the ECISS TC 1010/WG 1 committee, designated prEN 15627 [2]. It is hoped that by satisfying the current suggestions for small punch calibration and compliance to the European standard, multiple laboratories will be able to gain accreditation for small punch creep testing and offer a consistent market for such research and commercial testing

Small Punch Mechanical Calibrations

Operating Procedure

Findings

Discussion