論文
SCM435鋼の陰極水素チャージ下SSRT特性に及ぼす試験片直径の影響
2020 年 58 巻 5 号 p. 254-262
詳細
2020 年 58 巻 5 号 p. 254-262
As an alternative method to evaluation of slow strain rate technique (SSRT) under high-pressure hydrogen gas, SSRT tests were performed with a ca-thodically charged specimen. Cathodic charging was performed in 3% NaCl aqueous solution with pH＝6 and at a current density of 50 and 400 A/m2. Cr-Mo low alloy steel with a tensile strength of 1000 MPa grade was selected as a test material. Relative reduction of area (RRA) values obtained by tests with continuous charge at a cathode current density of 400 A/m2 were equivalent to those performed in hydrogen gas at pressure of 35 to 115 MPa. Fracture surface observations were also performed using scan-ning electron microscopy (SEM). The quasi-cleavage fracture surface of hy-drogen embrittlement (QCHE) was observed near the surface of specimen subjected to continuously hydrogen charged tests. QCHE rate on fracture sur-face increased with increasing cathodic current density and decreasing diam-eter of specimen. RRA decreased with increasing of the QCHE rate, reached the minimum value of RRA＝0.4 with the QCHE rate about 40%.
