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The role of ECAP in densification behaviour of PM aluminium alloy

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Powder metallurgy (PM) of aluminium alloys are used in a variety of industrial applications, such as the transportation (automotive and aerospace), and commercial areas. Light weight aluminium alloys, showing excellent workability, high thermal and electrical conductivity, represent a good choice for the PM industry to produce new materials with unique capabilities, not currently available in any other powder metal parts. Moreover, the requirement on mechanical properties (i.e. high tensile strength with adequate plasticity) should assure an increasing role for aluminium alloys in the expanding PM market. Due to their unique mechanical and physical properties, aluminium PM alloy parts are advantageous in engineering applications because of higher possibilities in material selection and design. Therefore, application of PM products is possible only if the designer understands the deformation characteristics of the virgin material. On the other hand, due to the presence of porosity in the aluminium PM parts, the deformation behaviour of the PM parts is considerably different from the conventional cast and wrought materials. It has already been extensively demonstrated that the mechanical and tribological properties of PM materials are directly controlled by their density and microstructure [1÷3]. Therefore a boost up in the application of PM materials could be derived from a complete knowledge of the mutual relationship between density (and/or porosity), composition and microstructure. Conventional PM method (press-and-sinter) is still most used process in PM production, mainly due to its cost effective properties. The process of powder pressing depends on a number of factors, such as the rheology (flow properties of powders during process), stress distribution within compacts and across particle-toparticle, hardness of particles (with respect the work hardening), strength distribution of particles, lubricant type and place of d[...]

Microstructure formation of CrNiMoV steel by hot plastic deformations

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The influence of deformations and deformation temperatures on austenite grain size, static recrystallization fraction of austenite and mechanical properties of high clean steel grade STN 41 6537 were investigated. This steel grade is used on forged rotors for steam turbines in power generation. S. 492 HUTNIK - WIADOMOŚCI HUTNICZE Nr 8 W pracy zbadano wpływ stopnia odkształcenia i temperatury o[...]

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