115 MPa水素ガス中におけるSCM435の水素誘起き裂進展下限界値<i>K</i><sub>I,H</sub>を求める試験方法

Translated title of the contribution: Test method for threshold of hydrogen-induced crack growth <i>K</i><sub>I,H</sub> of SCM435 in 115 MPa hydrogen gas

松岡 三郎, 濱田 繁, 吉田 聡子, 飯島 高志, 松永 久生, 山辺 純一郎

Research output: Contribution to journalArticle

Abstract

<p>In order to investigate the suitable test methods for determining threshold of hydrogen-induced crack growth, <i>K</i><sub>I,H</sub>, <i>J</i><sub>Ic</sub>, none-unloading <i>J</i><sub>Ic</sub>, constant-load and constant-displacement tests were conducted in 115 MPa hydrogen gas at room temperature, using SCM435 low alloy steels whose tensile strengths were between 824 and 1127 MPa. Constant-load and constant-displacement tests have been standardized by ASME KD-10 for determining <i>K</i><sub>I,H</sub> in hydrogen gas. <i>J</i><sub>Ic</sub> test has been standardized by ASTM E1820 for determining fracture toughness <i>J</i><sub>Ic</sub> or <i>K</i><sub>Ic</sub> in air. Recently, <i>J</i><sub>Ic</sub> test was done in hydrogen gas to obtain <i>K</i><sub>I,H</sub>. In this study, there were many cases when <i>J</i><sub>Ic</sub> tests were not conducted in hydrogen gas, because CT specimens broke before the first unloading. Then, none-unloading <i>J</i><sub>Ic</sub> test, where unloading processes were eliminated in <i>J</i><sub>Ic</sub> test, was employed in hydrogen gas. All four tests were done under small scale yielding in 115 MPa hydrogen gas. <i>K</i><sub>I,H</sub> obtained by four tests was almost the same. KD-10 demands that constant-load and constant-displacement tests of ferritic steels such as SCM435 are done for 1000 hours. Contrary to this, none-unloading test at displacement rate of 2×10<sup>-3</sup> mm/s was finished within one hour. It was concluded from these results that none-unloading <i>J</i><sub>Ic</sub> test was the best test for determining <i>K</i><sub>I,H</sub> in 115 MPa hydrogen gas. On the other hand, <i>J</i><sub>Ic</sub> test was the only test for determining <i>K</i><sub>Ic</sub> in air, because <i>K</i><sub>Ic</sub> was obtained under large scale yielding.</p>
Translated title of the contributionTest method for threshold of hydrogen-induced crack growth <i>K</i><sub>I,H</sub> of SCM435 in 115 MPa hydrogen gas
Original languageJapanese
Pages (from-to)17-00385-17-00385
Journal日本機械学会論文集
Volume84
Issue number857
DOIs
Publication statusPublished - 2018

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