[en] Specifications of the steel, for pressure vessels up to 700⁰C, are given: composition, mechanical properties, testing

[en] The fatigue crack growth behavior of 16Cr-5Ni-1.5Mo stainless steel was investigated. The steel was normalized and tempered at 800 deg C. Fatigue crack growth rates were measured using foil gage called Krak-gage. Constant load amplitude method and stepping loading method gave same results. The Paris law through 7-point polynomical regression method was as follows. da/dN=4.34 x 10^-9(ΔK)^3.00. (Author)

[en] Ion nitriding is a glow discharge process that is used to induce surface modification in metals. It has been applied to 316-L austenitic stainless steel looking for similar benefits already obtained in other steels. An austenitic stainless steel was selected because is not hardenable by heat treatment and is not easy to nitride by gas nitriding. The samples were plastically deformed to 10, 20, 40, 50 AND 70% of their original thickness in order to obtain bulk hardening and to observe nitrogen penetration dependence on it. The results were: an increase of one to two rockwell hardness number (except in 70% deformed sample because of its thickness); an increase of even several hundreds per cent in microhardness knoop number in nitrided surface. The later surely modifies waste resistance which would be worth to quantify in further studies. Microhardness measured in an internal transversal face to nitrided surface had a gradual diminish in its value with depth. Auger microanalysis showed a higher relative concentration rate C_N/C_Fe near the surface giving evidence of nitrogen presence till 250 microns deep. The color metallography etchant used, produced faster corrosion in nitrited regions. Therefore, corrosion studies have to be done before using ion nitrited 316-L under these chemicals. (Author)

[en] Reverse bending creep/fatigue tests have been performed on Type 316 steel at temperatures of 550 and 600⁰C for test durations of up to 12,000 h. It is shown that endurances obtained are comparable to those observed under push-pull conditions and that the introduction of a hold period can significantly reduce the endurance. Detailed fractography indicates that creep/fatigue in tension is more damaging than creep/fatigue in compression. The crack initiation behaviour is shown to be temperature dependent and may result from the combination of tensile and shear stresses, the relative importance of which will depend on the precise conditions of temperature, stress level and possibly microstructure. (author)

[en] The phenomenological description of the material was a series of interrupted tensile loading with strain-rate change from quasi-static to dynamic. These data clearly showed that the material strength, although strain-rate sensitive, is not affected by the strain-rate history, indicating that a mechanical equation of state could be applied. The Bodner-Partom constitutive theory is first calibrated by the monotonic stress-strain curves collected at steady constant strain rates, then used to predict the response under various types of interrupted strain-rate change tests. (orig./HP)

[en] The maximum power of short-time action generators is studied to increase the power of a turbogenerator designed for the tokamak power supply. Peculiarities in determining the maximum power as applied to bipolar synchronous generators (turbogenerators) with a rotating frequency of 3000 rev/min are considered. The problems of increasing flywheel power are considered. It is shown that the main factors, ensuring high level strength, viscosity and plasticity throughout the flywheel section are the usage of 25KhN3MFA and 35KhN3MFA steels under deep hardness penetration vacuum treatment of a liquid steel, ingot forging with upsetting, water or oil cooling with further high tempering. It is supposed that it permits to increase the diameter of a flywheel roll upto 1800 mm with a rotaling frequency of 3000 rew/min refusing to turn down a central opening, and to produce the 5x10⁹ J flywheel. Advisability for production of a bearing with 800 mm in diameter with the radial load upto 100 t is shown. Requirements to starting engines are enumerated

No abstract available

[en] Nuclear reactions produce solid and gaseous impurities in structural and cladding materials of nuclear reactors generated by: 1) He and H production from (n, α) and (n,p) nuclear reactions, respectively, in all reactor types. 2) Tritium to He decay in materials structure. A review is made of He effects on: a) properties of He atoms and its clusters, b) formation of He bubbles, and c) property changes due to He, emphasying the embrittlement evaluated by means of creep measurements. An analysis is made on the microstructure of stainless steel 316 before and after reactor irradiation. (author)

[en] The compatibility of HR-1, a hydrogen embrittlement resistant steel, with static liquid lithium was evaluated by mesuring its weight loss and observing the configuration of the corroded layer. The weight loss rate of HR-1 specimens was 4.86x10^-9 kg/m² s after exposure in liquid lithium at 773 K for 2440 h. The corroded layer was porous and could be spalled easily, Ni and Cr in the corroded layer were depleted by 90 and 92%, respectively, while the original austenite in the corroded layer has been turned into ferrite. (orig.)

[en] The sorption of gaseous tritium on the type 316 stainless steel was studied. The stainless steel was first contacted with gaseous tritium, and then the remaining tritium was evacuated. During a gradual etching from the surface by an acid solution, the tritium was released as HTO with a fraction of HT. They were radioassayed separately. The HTO mostly originates from the tritium present on the outer-most surface and about 90% of it could be released easily into water. However, the rest is sorbed tightly and remained in the surface layer. A fraction of the sorbed-tritium will diffuse atomically through the surface layer into the bulk of stainless and is released as HT by etching. The activation energy of the diffusion was determined as 32.9 kJ/mol. (orig.)