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[en] Molten Mn74Si26 and molten Mn33.5Si66.5 were investigated by neutron diffraction. The pair correlation function yielded, together with the X-ray results from a former paper, the partial coordination numbers, atomic distances, and the short range order parameter with the result that the atomic distribution in molten Mn33.5Si66.5 is statistical while the structure factor of molten Mn74Si26, as obtained with neutrons, shows a strong prepeak which means rather strong compound formation. (orig.)
[en] Austempered Ductile Iron (ADI) is a revolutionary material with high strength and hardness combined with optimum ductility and toughness. The discovery of two step austempering process has lead to the superior combination of all the mechanical properties. However, because of the high strength and hardness of ADI, there is a concern regarding its machinability. In the present study, machinability of ADI produced using conventional and two step heat treatment processes is assessed using tool life and the surface roughness. Speed, feed and depth of cut are considered as the machining parameters in the dry turning operation. The machinability results along with the mechanical properties are compared for ADI produced using both conventional and two step austempering processes. The results have shown that two step austempering process has produced better toughness with good hardness and strength without sacrificing ductility. Addition of 0.64 wt% manganese did not cause any detrimental effect on the machinability of ADI, both in conventional and two step processes. Marginal improvement in tool life and surface roughness were observed in two step process compared to that with conventional process. (paper)
[en] The present invention is in the field of metallurgy. Steels have found an increasing number of applications in mechanical constructions, and notably in the construction of materials for the production of energy and for the fabrication of welded structures operating under pressure. A possible application is the steam generators and volume compensators and other pressurized vessels of energy generating nuclear facilities with powers of up to 2 million kW. In order guarantee freedom from risks due to materials during the operation of nuclear plants, the steels used to fabricate the pressurized vessels employed must exhibit a sufficiently high performance in relation to: breaking load values, plasticity, resilience, brittle breaking resistance, embrittlement during thermal cycles.The steels of interest contain carbon, silicon, manganese, nickel, molybdenum, vanadium, aluminum, nitrogen, phosphorus and iron, but are characterized by the fact that they also contain cerium and antimony. The sum of the percentages of antimony and phosphorus is related to the percentage of manganese in the steel by the following relation: (Sb + P) < 0.011/Mn - 0.2
[fr]La presente invention concerne le domaine de la metallurgie. Les aciers ont recu une tres grande extension dans les constructions mecaniques, notamment dans la construction des materiels pour la production d'energie, pour la fabrication de structures soudees travaillant sous pression, par exemple de generateurs de vapeur et de compensateurs de volume, ainsi que d'autres recipients sous pression, des unites nucleaires de production d'energie d'une puissance allant jusqu'a 2 millions de kW. Pour garantir l'exploitation sans risque du materiel des centrales nucleaires, les aciers destines a la fabrication des recipients sous pression doivent satisfaire a une serie de prescriptions: les valeurs de la charge de rupture, de la plasticite, de la resilience, de la resistance a la rupture fragile, de la resistance a la fragilisation lors des actions thermiques doivent etre elevees. Acier du type constitue par du carbone, du silicium, du manganese, du nickel, du molybdene, du vanadium, de l'aluminium, de l'azote, du phosphore, du fer, caracterise en ce qu'il contient aussi du cerium et de l'antimoine. La somme des pourcentages d'antimoine et de phosphore etant liee au pourcentage de manganese dans l'acier par la relation: (Sb + P) < 0,011/Mn-0,2
[en] In this paper, we report the microstructure and hydrogen storage properties of TiFe + 4 wt% (Zr + 2Mn) alloy before and after high-energy milling. The as-cast sample was made of a main TiFe phase with a Zr- and Mn-rich secondary phase. We found that ball milling can significantly reduce the crystallite size of TiFe + 4 wt% (Zr + 2Mn) alloy. First hydrogenation measurements showed that the sample milled for 15 min displayed a faster hydrogenation than the as-cast sample but with a slight loss of capacity. Further milling made the samples totally inert to hydrogen. It may be concluded that the as-cast alloy has a special microstructure that is possibly destroyed by milling.
[en] The Al-Mn-W system has considerable potential as a basis for lightweight aluminum alloys that are intended for use at temperatures approaching 350 °C (623 K). In this ternary system, aluminum, manganese, and tungsten co-precipitate to form the meta-stable Al12(Mn(1-x)Wx) phase, which is thermally stable and will not coarsen when held at elevated temperatures for extended periods of time. This enhanced thermal stability of the Al12(Mn(1-x)Wx) phase in comparison to the Al12Mn phase which forms in binary Al-Mn alloys is explained in terms of the Gibbs free energy of the two phases. It is shown that co-precipitating tungsten with aluminum and manganese lowers the Gibbs free energy of the precipitated phase and by so doing, it slows down its coarsening rate and enhances its thermal stability.
[en] The effect of alloying elements carbon, manganese and aluminum on the microstructural evolution of lightweight steels during a typical steel production process has been investigated experimentally and on the basis of a thermodynamic calculation. It is proposed how the information from thermodynamic calculations should be utilized for the interpretation of microstructural evolution during a real steel production process. It is demonstrated that the equilibrium thermodynamic calculation can be successfully utilized for the interpretation of non-equilibrium microstructural evolution after some calibration.