Hydrogen-involved tensile and cyclic deformation behavior of low-alloy pressure vessel steel

Abstract

The temperature-and strain-rate-dependent tensile behavior of hydrogen-charged low-alloy pressure vessel steel ASTM A508 C1.3 has been investigated. The fatigue crack initiation and propagation behavior of the steel in high-temperature water environments has also been evaluated. It was found that hydrogen played significant roles in both tensile and cyclic deformation processes, especially in the temperature and strain-rate region of dynamic strain aging (DSA). The presence of hydrogen resulted in a distinct softening in tensile strength and a certain loss in tensile ductility in the DSA region. Remarkable degradation in fatigue crack initiation and propagation resistance in high-temperature water environments was observed in the DSA strain-rate region. Typical hydrogen-induced cracking features also appeared on the corresponding fatigue fracture surfaces. The interactions between hydrogen and DSA in tensile and cyclic deformation processes are discussed as well as their combined effects on the environmentally assisted cracking (EAC) mechanism of pressure vessel steels in high-temperature water environments.

Effect of gaseous hydrogen charging on the tensile properties of standard and medium Mn X70 pipeline steels

“…However, these are likely to be slightly underestimated because the reference total strain was taken as that for Ar at 25 o C, as due to limitation in the number of samples, elevated temperature tensile testing was not conducted on argon-charged samples. The increase in total elongation with test temperature increase is in agreement with the literature [23,24]. Similarly, the decrease in yield and tensile strengths with increasing temperature is in agreement with the results of Michler's [25] which covered a lower temperature range (-80˚C to 20˚C).…”

Effects of Hydrogen Diffusion on the Mechanical Properties of Austenite 316L Steel at Ambient Temperature

“…While the homogenization heat-treatment was able to achieve the uniform hydrogen distribution, some degree of hydrogen desorption might have occurred during the process, considering the relatively lower hydrogen contents and decrease in hydrogen concentration after surface removal, as compared to those ranging from several to a few hundred ppm reported in other studies. 8,22) Considering the usual residual hydrogen concentration of 1:7$1:8 ppm in an as-received 316L austenitic stainless steel 17) and assuming the similar range of hydrogen concentration in our asreceived sample, the hydrogen concentration in our Hcharged and homogenized specimen is approximately only three times the residual hydrogen concentration at the highest. Therefore, our discussion is confined to the effect of a 'small' amount of 'internal' hydrogen on austenitic 316L stainless steel.…”

“…[5][6][7] As such, the HE phenomenon in steels is an important subject and has been examined by a number of researchers for advanced structural applications, such as nuclear power plants and gas/oil industry where there are several hydrogen sources. [8][9][10][11][12] In particular, 316L austenite stainless steels are becoming increasingly popular as advanced structural materials in light water reactors (LWRs) or liquid metal reactors (LMRs) in nuclear power plants owing to their combination of strength and ductility, fracture toughness, corrosion resistance as well as low absorption rate of neutron radiation. [13][14][15] For the HE study, the interaction between hydrogen and steels is generally induced either by cathodic or gas-phase charging.…”

“…In this study, the forced charging of hydrogen was achieved also using a cathodic charging technique to simulate the mechanistic role of hydrogen in 316L austenite stainless steels. Furthermore, unlike previous studies, 8,10,12,21,22) the H charging process was followed by a high-temperature heat-treatment to remove the initially inhomogeneous hydrogen concentration gradient that usually occurs after cathodic charging. 12,21,23) The room-temperature tensile properties of the 316L austenite stainless steel with and without the homogenization process were examined and compared at different strain rates.…”

Hydrogen Absorption and Desorption in Steel by Electrolytic Charging

“…This phenomenon is called hydrogen embrittlement [1,2,3,4]. Many studies were conducted on the diffusion and trapping of hydrogen in steel [4,5,6,7,8,9,10] and other metals [10].…”