Effect of nickel equivalent on hydrogen gas embrittlement of austenitic stainless steels based on type 316 at low temperatures

Internal Reversible Hydrogen Embrittlement of Austenitic Stainless Steels Based on Type 316 at Low Temperatures

“…These fractures along the prior annealed-twin boundary and brittle transgranular fractures in H-charged specimens are also observed in the specimens fractured in 1 MPa hydrogen at low temperatures. 56) This brittle transgranular fracture mode is observed on the H-charged specimens fractured at temperatures from 200 to 300 K. However, fractures along the prior annealed-twin boundary are observed at 200 and 250 K. Large dimple ruptures together with brittle transgranular fractures are observed in the 316-5 specimen, as shown in Fig. 6(c), whereas fine dimple ruptures are observed in all as-solution-annealed specimens not shown here.…”

“…4, where we added Ni content on the figures published previously. 56) The ferrite equivalent near the fracture surfaces is measured by the magnetic method after the specimen fractured in helium, and the maximum measured value of each specimen is plotted in the figure. The ferrite equivalent measured by this method corresponds to the content of strain-induced α' martensite in the fractured region.…”

“…Thus, all tests were conducted by SSRT at a strain rate of 4.2 × 10 -5 s -1 , which is the same as that used in our HGE tests, 56) to ensure a substantial effect of hydro- gen on the mechanical properties of the alloys in our investigation of HGE. The fracture surfaces of the specimens after tensile tests were analyzed by scanning electron microscopy (SEM).…”

“…The Ni content of Fe (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)Ni17Cr2Mo alloys based on type 316 austenitic stainless steel, which were used in our previous study on HGE at low temperatures, 56) was varied from 10 to 20% to study the effect of Ni content on IRHE at low temperatures. We refer to these alloys as Ni-added type 316 alloys in this paper.…”

“…Caskey 11) showed that the HGE of iron-chromium-nickel stainless steels decreases markedly in the Ni composition range from 8 to 14%, which is associated with an increase in austenitic phase stability, and attributed HE not to the martensite content but to the Ni and N contents. We also found such a chemical composition dependence at temperatures above 200 K. 15,20,47) We also studied the HGE of Fe (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)Ni17Cr2Mo alloys based on type 316 stainless steel in 1 MPa hydrogen at low temperatures 56) and found that HGE increases with decreasing temperature, attains a maximum at 200 K and decreases with further decreasing temperature. In this study, the IRHE of Fe (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)Ni17Cr2Mo alloys was investigated in the temperature range from 80 to 300 K as a follow-up to the above HGE study.…”