High Temperature Fatigue Life Evaluation Using Small Specimen

Abstract

For developing the high temperature fatigue life evaluation method using small specimen, the effect of specimen size and test environment on the high temperature fatigue life of the reduced activation ferritic/martensitic steel, F82H-IEA, was investigated at 550• C under the total strain range of 0.5 -1.2 % using a new high temperature low cycle fatigue testing machine for the small round-bar specimen. No significant effect of the test environment (oxidation) on the fatigue life was observed in the standard-size specimen, whereas the slight reduction of the fatigue life due to that was indicated in the small-size specimen, especially at the final fracture stage of the test. It could be concluded that the new high temperature low cycle fatigue testing machine of the present study could satisfy the minimum requirements for the high temperature low cycle fatigue life evaluation using small specimen because the fatigue life data obtained using this testing machine could be acceptable based on the comparison with the previous studies data. To improve the reliability and the applicability of this test technology, further evaluations under the wider test temperature and strain conditions are expected in future.

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

“…Sub-size standard specimens have been used to determine low cycle fatigue life for steels 155,157,171,205 and nickel alloys. 124,125 All tests were done with fully reversible loading.…”

Analytical and inverse method for determining high temperature properties of materials using small punch creep: a review

“…On the above basis, the demands for mechanical property characterization have led to a considerable impetus of miniaturized specimen design in two directions. The principle of the first scope in designing miniaturized specimen is proportionally scale-down the dimension referring to its conventional full-scale counterparts, such as the sub-size specimen (Nogami et al ., 2013, 2017; Nozaki et al ., 2020). In the second scope (Abendroth and Kuna, 2003, 2004; Campitelli et al ., 2004; Hyde et al ., 2013b; Sastry, 2005), efforts have been paid to produce innovative geometry and experimental configuration that have no special equivalent, such as small punch creep test (SPCT) (Blagoeva et al ., 2011; Zhong et al ., 2019; Arroyo et al ., 2019), impression creep test (ICT) (Sastry, 2005; Hyde et al ., 1996), small ring creep test (SRCT) (Hyde et al ., 2013b; Yu et al ., 2021) and small tensile two bar creep test (STBCT), as illustrated in Figure 1.…”

“…However, over the past decades, an alternative technique, named as “miniaturized testing”, had been evolved as a non-invasive approach to obtain material property for structural integrity evaluation. In order to maximize the diversity of measured mechanical properties and minimize the cost, significant efforts have been made to develop a substantial variety of miniature testing, from which a series of various properties can be derived, such as tensile (Zhang et al ., 2021; Zhong et al ., 2019; Janča et al ., 2016), fatigue (Lancaster et al ., 2019; Nogami et al ., 2013, 2017), fracture toughness (Hurst et al ., 2019; Kumar et al ., 2017; Arroyo et al ., 2019), fatigue crack growth (Matsushita et al ., 2021; Wan et al ., 2019b) etc.…”