Aluminum alloys are important in aerospace industry, due to their mechanical properties, low specific weight and good corrosion resistance. Such properties are achieved due to a heat treatment of solubilization, quenching and aging, in order to precipitate metastables phases, which act as dislocation obstacles, increasing the strength of the alloy. In the present study, the precipitation sequence of Al-8%Ag alloy was analyzed via Vickers hardness and Transmission Electron Microscopy. The size and morphology of the precipitated particles, involved in the stages of precipitation process was characterized. It was determined the microstructure at the peak hardness, which is mainly composed of spherical GP zones with about 6 nm average diameter, which are responsible for the alloy achieve a value of 72 HVN. It was observed that this hardness value does not compete with others well known alloys, like AA 6061 and AA 2024, which can be precipitation hardened. The main reason for the low values of HVN, is because of there is no enough difference between the matrix and the precipitated particles lattice parameters, and dont cause a significant elastic strain by coherence in the matrix lattice, that could produce a substantial hardening. To ascertain this assumption, the aged material was severely plastic deformed, achieving 94 HVN, and the grain refinement and high dislocations density were the major hardening mechanisms, since the precipitates behavior was similar as the matrix, because particles were distorted instead of acting as impediment to material flow.
Los aceros inoxidables austeníticos AISI 316L son muy comunes en la industria. Grandes cantidades de este material se desechan como chatarra y pueden utilizarse posteriormente como material reciclado para la colada. En ambientes marinos (altamente corrosivos), este tipo de acero presenta corrosión intragranular, específicamente en una de sus fases, en la ferrita, por lo que se prefiere mantenerla en la menor proporción posible (1%), pero normalmente se encuentra alrededor del 12%. Si se requiere que una pieza de fundición de acero AISI 316L transporte un fluido presurizado, debe realizarse de acuerdo con las consideraciones descritas en la norma ASTM A351. En este trabajo, se encontró que el acero CF3M tiene mayor solicitud en términos de proporciones químicas elementales de sus componentes. Por lo tanto, se utilizaron los diagramas de Schaeffler y Schoefer para reducir el contenido de "ferrita equivalente" en al menos el 90%, haciendo ajustes en la fundición modificando los porcentajes de Ni y Cr.
This paper presents the results of a research project obtained using theoretical, numerical and experimental methods, in order to solve the problems encountered when increasing the height of a double deep drawing sink, and the proposed solution. The analysis considers: Manufacturer limitations (eg. tool modifications, steel material changes etc.), the process parameters observed and measured during the deep drawing operation of the failure part, the theoretical fundamentals of sheet metal forming and the analysis and simulation with a computer program based in the finite element method (FEM). The analysis and simulation results using a FEM program showed that, it is possible the height increment of the sink, utilizing a variable blankholder force, to an 11% above from the fabricated parts before the application of the proposed solution but 5% less than the required final product height.
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