PSI - Issue 19

Akira Ueno et al. / Procedia Structural Integrity 19 (2019) 494–503 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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the other hand, final target of H 2 tank of an FCV in Japan, hydrogen pressure should be more over 70 MPa for a considerable range. Also, a hydrogen station and their peripheral equipment are exposed to high-pressure H 2 gas. Therefore, for designing metallic components of Hydrogen gas systems, effect of high-pressure H 2 gas should be considered. There are lots of papers for studying a hydrogen embrittlement (HE). Although there are not enough papers referred to the effect of high-pressure H 2 on the HE phenomenon. In this study, an effect of high-pressure H 2 gas on tensile and fatigue properties of stainless steel SUS316L were investigated by means of the internal high-pressure H 2 gas technique .

Nomenclature  a

stress amplitude (MPa)

 mean mean stress (MPa)  w fatigue limit (MPa)   hoop stress (MPa) R stress ratio N f

number of cycles to failure (cycle)

s

striation spacing (mm)

stress intensity factor range (MPa √ m)

 K

reduction of area (%)



RRA Ni eq

relative reduction of area (%)

Ni equivalent (%)

2. Experimental procedure

2.1. Internal high-pressure H 2 gas technique

An internal high-pressure H 2 gas technique as a simple testing method was proposed by Ogata, T. (2008, 2018). Fig. 1 (a)-(d) show specimen for this technique. As shown in Fig. 1(a) & (b), specimen has thin and deep through hole of 1 mm diameter dug with an electric discharge machine. After blockading both ends of specimen with screw bolts and special sealant, then high pressure H 2 gas were injected into specimen inside with an adopter attached to specimen side edge (Fig.1(c) & (d)). A hydrogen gas pressure using in this study was 14.7 MPa (=147 atm). Before injecting H 2 gas, inside of a thin hole was evacuated by vacuum pump as shown in Fig.2.

Fig. 1 Specimen for the internal high-pressure H 2 gas technique.