Browsing by Keyword "Heat treatments"
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Item Creep failure mechanisms of a Ti-6Al-4V thick plate(2001-11) Seco, F. J.; Irisarri, A. M.; Tecnalia Research & InnovationThe creep failure operating mechanisms of a 17-mm thick plate of a Ti-6Al-4V alloy in various heat treating conditions have been investigated. Specimens in the as-received, mill-annealed, condition (50 min maintenance at 720°C and air cooled as the final step of the thermomechanical process) showed the lowest creep resistance and their metallographic analysis revealed that the temperature-activated dislocation climb was the mechanism responsible for the failure and that observed holes were generated by plastic deformation, rather than by creep cavitation. Conversely, maximum times to failure were recorded in beta-annealed specimens (1030°C for 30 min, air cooled and aged for 2 h at 730°C). The fracture surfaces of these broken specimens exhibited an intergranular morphology that was attributed to grain boundary sliding along the former beta grains. Finally, alpha-beta field-annealed samples (940°C 4 h, and furnace cooled at 700°C) possessed intermediate lives between those of mill-annealed and beta-annealed specimens and the failure operating mechanism was diffusional creep by the nucleation and coalescence of the creep cavities generated at the alpha-beta interfaces and the triple points.Item Heat treatments effect on A357 components produced by SSM(Trans Tech Publications Ltd, 2006) Forn, A.; Baile, M. T.; Martín, E.; Goñi, J.; Sarriés, I.; Centros PRE-FUSION TECNALIA - (FORMER)The present work studies the effect the solution heat treatment, during artificial ageing and re-aging, has on the mechanical properties of an A357 aluminium alloy component formed by New Rheocasting. The effect that the evolution of silicon, during the solution treatment at various times, has on the mechanical properties was also examined. The mechanical properties were evaluated performing tensile tests, fractographical analysis and hardness tests. The microstructural characterization was made using optical and electronic microscopy.Item Heat treatments effect on A357 components produced by SSM(2006) Forn, A.; Baile, M. T.; Martín, E.; Goñi, J.; Sarriés, I.; Centros PRE-FUSION TECNALIA - (FORMER)The present work studies the effect the solution heat treatment, during artificial ageing and re-aging, has on the mechanical properties of an A357 aluminium alloy component formed by New Rheocasting. The effect that the evolution of silicon, during the solution treatment at various times, has on the mechanical properties was also examined. The mechanical properties were evaluated performing tensile tests, fractographical analysis and hardness tests. The microstructural characterization was made using optical and electronic microscopy.Item Wire arc additive manufacturing Ti6Al4V aeronautical parts using plasma arc welding: Analysis of heat-treatment processes in different atmospheres(2020) Artaza, Teresa; Suárez, Alfredo; Veiga, Fernando; Braceras, Inigo; Tabernero, Iván; Larrañaga, Oihane; Lamikiz, Aitzol; FABRIC_INTEL; Tecnalia Research & Innovation; INGENIERÍA DE SUPERFICIESPAW (Plasma Arc Welding), a WAAM (Wire Arc Additive Manufacturing) technology with high deposition rates, can produce metallic components, layer by layer, of varied sizes, from different alloys, yielding high mechanical performance. Two Ti6Al4V walls are manufactured in an inert argon atmosphere using WAAM-PAW to analyze the deposition process in terms of growth in height per layer, deposition process temperature, and cooling times. The properties of the walls are compared with the values obtained from a thermomechanical simulation and both the microstructural and mechanical properties of the annealed WAAM-PAW wall are studied. Moreover, the effect of the media on the oxidation layer and on the mechanical properties are also analyzed throughout the heat treatment process, as well as the microstructure of Ti6Al4V. Stable deposition rates were achieved for a high deposition ratio of Ti6Al4V at 2 kg/h, restricting the oxygen levels to under 100 ppm. No significant differences were found in either the microstructural or the mechanical properties following heat treatments in a vacuum, in air or in argon. All the heat-treated samples met the AMS4928 standard for Yield Strength (YS) and Ultimate Tensile Strength (UTS).