Logo do repositório

Percorrer por autor "Rodrigues, D. M."

A mostrar 1 - 3 de 3
  • Effect of friction stir processing parameters on the microstructural and electrical properties of copper
    Publication . Leal, Rui; Galvão, I.; Loureiro, A.; Rodrigues, D. M.
    Friction stir processing (FSP) is an innovative technology, based on friction stir welding (FSW) operative principles, which can be used for changing locally the microstructure and the mechanical properties of conventional materials. In this work, the copper alloy C12200 was friction stir processed using two distinct tools, i.e. a scrolled and a conical shoulder tool, in order to promote different thermomechanical conditions inside the stirred volume, and consequently, varied post-processed microstructures. The influence of the tool geometry and tool rotation and traverse speeds on the microstructural and electrical properties of the processed copper alloy was analysed. The processing conditions were found to have an important influence on the electrical conductivity of the processed material. The differences in electrical conductivity were explained based on dislocations density effects. The effect of the dislocations density on electrical conductivity of the processed material was found to prevail over the effect of the grain boundaries.
    2015-04Artigo científico Acesso restrito Ver mais
  • Effect of shoulder cavity and welding parameters on friction stir welding of thin copper sheets
    Publication . Leal, R. M.; Sakharova, N.; Vilaça, P.; Rodrigues, D. M.; Loureiro, A.
    The aim of this investigation was to study the influence of shoulder cavity and welding parameters on torque, defect formation, microstructure and mechanical properties of friction stir welds in very thin sheets of deoxidised copper. Three types of tools were used: a flat shoulder tool and two tools with conical shoulder cavities of 3 and 6° respectively. The welding parameters analysed were tool rotation and traverse speeds. It was observed that the torque, the microstructure and hardness and the formation of defects in the welds are influenced mainly by tool rotation speed and, to a lesser extent, by the traverse speed and shoulder cavity. The tensile properties of welds carried out at high rotation speeds are little affected by the shoulder cavity.
    2011-02Artigo científico Acesso aberto Ver mais
  • Microstructural and mechanical characterisation of 5XXX-H111 friction stir welded tailored blanks
    Publication . Tronci, A.; McKenzie, R .; Leal, Rui; Rodrigues, D. M.
    Friction stir welds in 1 mm thick plates of AA 5182-H111 and AA 5083-H111 aluminium alloys are analysed in this paper. The welds were produced using a large range of welding conditions, namely, different process control modes (position and load control), tool parameters (different geometries and dimensions) and process parameters (rotation speed, advancing speed and axial load). Visual inspection and metallographic and mechanical analysis demonstrate that it is possible to obtain consistently good quality welds in very thin plates under a large range of welding conditions. Important relations between base material properties, tool geometry and the final properties of the welds were established.
    2011-07Artigo científico Acesso restrito Ver mais