Effect of Hydrogen on the Tensile Properties of 900-MPa-Class JIS-SCM435 Low-Alloy-Steel for Use in Storage Cylinder of Hydrogen Station

Abstract

We investigated the effect of hydrogen on the tensile properties of a quench tempered low alloy steel, SCM435, with the tensile strength of 930 MPa used for hydrogen storage cylinders. Tensile specimens were machined from a cylinder with the inside and outside diameters of 245 and 315 mm. The specimens were immersed in a 20 mass aqueous solution of ammonium thiocyanate (NH 4 SCN) at 313 K for 48 hours and then charged with hydrogen. Tensile tests were performed in the air at room temperature. The cross head speed was ranged from 0.01 to 100 mm/min. Hydrogen charged specimens were hold in the air for a period of 1 and 300 hours. The 0.2 proof stress and tensile strength for the hydrogen charged specimens were similar to those for the uncharged specimens, whereas the reduction of area was lower in the hydrogen charged specimens than in the uncharged specimens. Thermal desorption spectroscopy showed that the residual hydrogen contents in the hydrogen charged specimens fractured by tensile tests were between 0.14 and 0.93 mass ppm. The reduction of area of the hydrogen charged specimens decreased linearly with increasing residual hydrogen content. Scanning electron microscopy showed that the cup corn fracture occurred in the hydrogen charged and the uncharged specimens and that the fracture surfaces were covered with dimples. The normal stress fracture area in the center of the hydrogen charged and uncharged specimens was almost the same. The shear stress fracture area near the specimen surface was wider in the hydrogen charged specimens than in the uncharged specimens. This means that hydrogen enhances slip deformation near the specimen surface and resulted in the lower reduction of area in the hydrogen charged specimen. We therefore concluded that the hydrogen embrittlement behavior of the 900 MPa class SCM435 steel was explained by the hydrogen enhanced localized plasticity model rather than by the lattice decohesion model.

Characterization of Void Coalescence in Alpha-Iron in the Presence of Hydrogen

“…This figure shows that hydrogen reduces the stress in all models. This result is consistent with the experimental result (27) . Figure 3 shows that the stress in the model with a square void array with f 0 = 0.14 is larger than the model with f 0 = 0.08.…”

Investigation of hydrogen transport behavior of various low-alloy steels with high-pressure hydrogen gas

“…This confirmed that the entry of hydrogen into nonsputtered specimens, which contain native oxide layers on the surface, at RT does not occur by a diffusion-controlled process and that there is a significant surface effect on the entry of hydrogen. The hydrogen-entry behavior in highpressure hydrogen gas therefore differs from that in ordinary electrochemical charging [35].…”

Absorption of Hydrogen in High-strength Low-alloy Steel during Tensile Deformation in Gaseous Hydrogen

“…In S1 and S2, C H increased with increased tensile strain up to about 0.005, and then did not show monotonic increase with tensile strain. Meanwhile, C H linearly increased with the strain up to about ρ ε ϭ ϫ 14 4 . 0.004 in S3 and S4.…”

“…1) In low-alloy steels, it is well known that the susceptibility of HEE increases as the strength increases. 2) Recently, some studies on HEE of carbon steels and high-strength low-alloy steels, which are used for highpressure hydrogen components, [3][4][5][6] in a high-pressure hydrogen environment have been conducted to evaluate their mechanical properties in this circumstance.…”