Methods and Devices for Small Specimen Testing at the Japan Atomic Energy Research Institute

Abstract

Devices for a punch test on annular notched specimens, small punch (SP) tests, and miniaturized tension tests in hot cells were developed. A micro-manipulator to handle small specimens and an electro-discharge machine (EDM) to extract miniaturized tension specimens and annular notched specimens from transmission electron microscopy (TEM) disks were also fabricated. These devices were designed and made for remote operation in hot cells. Preliminary tests to evaluate the applicability of test methods were carried out. Correlation between SP test results and tensile properties was not strong. Miniaturized tensile results were reasonably similar to the results with larger specimens. The ductile-brittle transition temperature (DBTT) by the punch test on annular notched specimens was higher than that obtained from the SP test. However, materials dependence of the DBTT was different from that measured by standard Charpy V-notch (CVN) tests. This may be due to a specimen size effect.

Small specimen techniques for estimation of tensile, fatigue, fracture and crack propagation material model parameters

“…Increasing the clamping force increases the maximum load measured, therefore an appropriate clamping force needs to be chosen to get material properties representative of bulk material. 68 Increasing cold work increased maximum force, 184 which was also as expected, however maximum displacement did not depend on cold work. Orientation was found to be very significant, so if the material is anisotropic it should be tested in the appropriate direction.…”

“…This was done exclusively for steels, with varied SPT specimen dimensions. 30,48,53,59,68,71,81,82,184 The results showed that the yield load (P s in Figure 29) did not depend on punch diameter, but varied as a square of sample thickness. Maximum load (P m ) increased with sample thickness 53 and punch diameter.…”

“…49,63,64 Varying the thickness was found to have an effect, however it is negligible between 0.29 and 0.4 mm for a punch diameter of 1 mm. 78 Correlations were used to find yield strength from miniaturized tensile specimen test results, 184 while inverse FEA was used to find it from the disc tensile specimen test results. 181 The use of correlations resulted in good agreement with standard testing results and inverse FEA results were within 2% of standard testing results.…”

“…78 Shear punch jump test, producing similar data to tensile jump test, also resulted in good agreement between calculated UTS and uniaxial UTS. 15 The more unusual specimens were the miniaturized tensile specimens and disc tensile specimens, one of which relied on correlations 184 and the other on inverse FEA. 181 ABI was also used, with a series of calculations applied in order to calculate UTS and it achieved reasonably good agreement with uniaxial results.…”

Evaluation of fatigue damage in materials using indentation testing and infrared thermography

“…Typically, material property is evaluated through small specimen test method to evaluate tensile [1][2][3][4][5], impact [6,7] and fracture toughness properties [8,9] and in a few cases fatigue properties are evaluated through sub-size hourglass specimens [10]. Fatigue crack growth experiments have been carried out using miniature specimens [11,12] to estimate the degradation in performance due to irradiation.…”