炭素鋼の高圧水素ガス中SSRT試験における水素誘起表面き裂進展に及ぼすパーライトの影響

抄録

Carbon steels are well known for their high susceptibility to hydrogen; therefore, the use of the materials in high-pressure hydrogen is highly restricted under current regulations. The authors have reported that, for example, in slow strain rate tensile (SSRT) test of a low carbon steel in 115-MPa hydrogen gas, fracture was caused by growth of cracks initiated at specimen surface, and accordingly ductility decreased compared to that in air. Therefore, the behavior of surface cracking is the key to figure out the material compatibility for hydrogen. In this study, SSRT tests were performed using interstitial free (IF) steel and low carbon steels, JIS-S10C, S25C, S45C, with different carbon contents. The tests were carried out in air and in 95-MPa hydrogen gas at room temperature. And the effect of hydrogen was investigated based on the crack length-true strain curves (crack growth curves) obtained by observing the cracks at specimen surface of fractured specimens.