Study on temper embrittlement and hydrogen embrittlement of a hydrogenation reactor by small punch test

The study on temper embrittlement and hydrogen embrittlement of a test block from a 3Cr1Mo1/4V hydrogenation reactor after ten years of service was carried out by small punch test (SPT) at different temperatures. The SPT fracture energy E-sp (derived from integrating the load-displacement curve) divided by the maximum load (F-m) of SPT was used to fit the E-sp/F-m versus-temperature curve to determine the energy transition temperature (T-sp) which corresponded to the ductile-brittle transition temperature of the Charpy impact test. The results indicated that the ratio of E-sp/F-m could better represent the energy of transition in SPT compared with E-sp. The ductile-to-brittle transition temperature of the four different types of materials was measured using the hydrogen charging test by SPT. These four types of materials included the base metal and the weld metal in the as-received state, and the base metal and the weld metal in the de-embrittled state. The results showed that there was a degree of temper embrittlement in the base metal and the weld metal after ten years of service at 390 degrees C. The specimens became slightly more brittle but this was not obvious after hydrogen charging. Because the toughness of the material of the hydrogenation reactor was very good, the flat samples of SPT could not characterize the energy transition temperature within the liquid nitrogen temperature. Additionally, there was no synergetic effect of temper embrittlement and hydrogen embrittlement found in 3Cr1Mo1/4V steel.Web of Science106art. no. 67

On the assessment of non-metallic inclusions by part 13 of API 579 -1/ASME FFS-1 2016

Improvement of nondestructive inspection techniques has allowed more frequent detection of closely spaced zones of non-metallic inclusions in pressure vessels made of low carbon steel. In the present study, closely spaced inclusions in an in-service cylindrical horizontal pressure vessel were detected by Scan-C ultrasonic inspection and considered as laminations to be assessed by Part 13 of the API 579-1/ASME FFS-1 2016 standard. The outcoming results were considered as a rejection for Level 1 assessment, and a repair or replacement of the component was required, even though it retained a significant remaining strength. Thus, an alternative procedure to assess the mechanical integrity of pressure vessels containing zones of non-metallic inclusions is proposed by adopting some criteria of the API 579-1/ASME FFS-1 Part 13 standard procedure and taking into consideration the dimensions and grouping characteristics of the inclusion zones.    &nbsp

DFT + U study of the adsorption and dissociation of water on clean, defective, and oxygen-covered U3Si2{001}, {110}, and {111} surfaces

The interfacial interaction of U3Si2 with water leads to corrosion of nuclear fuels, which affects various processes in the nuclear fuel cycle. However, the mechanism and molecular-level insights into the early oxidation process of U3Si2 surfaces in the presence of water and oxygen are not fully understood. In this work, we present Hubbard-corrected density functional theory (DFT + U) calculations of the adsorption behavior of water on the low Miller indices of the pristine and defective surfaces as well as water dissociation and accompanied H2 formation mechanisms. The adsorption strength decreases in the order U3Si2{001} > U3Si2{110} > U3Si2{111} for both molecular and dissociative H2O adsorption. Consistent with the superior reactivity, dissociative water adsorption is most stable. We also explored the adsorption of H2O on the oxygen-covered U3Si2 surface and showed that the preadsorbed oxygen could activate the OH bond and speed up the dissociation of H2O. Generally, we found that during adsorption on the oxygen-covered, defective surface, multiple water molecules are thermodynamically more stable on the surface than the water monomer on the pristine surface. Mixed molecular and dissociative water adsorption modes are also noted to be stable on the {111} surface, whereas fully dissociative water adsorption is most stable on the {110} and {001} surfaces

Oxidation behaviour of U3Si2: an experimental and first principles investigation

Uranium-containing metallic systems such as U3Si2 are potential Accident Tolerant Fuels (ATFs) for Light Water Reactors (LWRs) and the next generation of nuclear reactors.</p

Review of Current Developments on High Strength Pipeline Steels for HIC Inducing Service

Nowadays, an increasing number of oil and gas transmission pipes are constructed with high-strength low alloy steels (HSLA); however, many of these pipelines suffer from different types of hydrogen damages, such as hydrogen-induced cracking (HIC). So many research efforts are being carried out to reduce the detrimental effects of hydrogen damage in HSLA steel pipes. The thermomechanical control process (TMCP) is a microstructural control technique that is able to eliminate the conventional heat treatment after hot rolling. Recent research demonstrated that TMCP provides high HIC resistance without adding high amounts of alloying elements or expensive heat treatments. However, once these HSLA steel pipes are put into service, they experience HIC damage, and the prediction of its kinetics is a necessary condition to perform Fitness-For-Service assessments. To develop a reliable predictive model for the kinetics of HIC, the relations among the microstructural features, environmental parameters, and mechanical properties have to be fully understood. This paper presents a review of the key metallurgical and processing factors to develop HSLA steel pipes, as well as a review of the phenomenological and empirical models of HIC kinetics in order to identify specific research directions for further investigations aimed to establish a reliable and sound model of HIC kinetics. &nbsp

Texture evolution and plastic anisotropy of commercial purity titanium/SiC composite processed by accumulative roll bonding and subsequent annealing

The final publication is available at Elsevier via https://doi.org/10.1016/j.matchemphys.2018.08.027. © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/In this study, commercial purity titanium (CPTi) with SiC particle reinforcements produced using accumulative roll bonding (ARB) process and subsequent annealing. Texture evolution and plastic anisotropy in different steps of the process were studied. ARBed material exhibited a significant magnitude of anisotropy of mechanical properties. Moreover, a strong TD split basal texture with basal poles tilted 25° away from the normal direction toward the transverse direction was developed in the ARBed samples. Higher normal anisotropy obtained for ARB–annealed sheet, compared to that of the starting titanium sheet, indicated lower susceptibility to thinning. However, ARB–annealed sheet exhibited higher planar anisotropy ( = 0.048 for ARB–annealed sheet and  = –0.434 for starting titanium). Higher resistance to thinning of the ARB–annealed sheets compared to the starting titanium was ascribed to the higher uniform elongation shown by annealed sheets. Furthermore, it was concluded that finer grain size of ARB–annealed sheet resulted in higher work hardening of the sheet, which in turn, increased the uniform elongation of ARB–annealed sample

Religia a współczesne stosunki międzynarodowe

Praca recenzowana / peer-reviewed pape