2013 年 63 巻 5 号 p. 182-187
Precipitates refinement of hypereutectic Al–Si alloy is effective for improvement of its mechanical properties. Our original severe plastic deformation process named Compressive Torsion Process is effective for not only grain refinement but also precipitates refinement. In the present work, Compressive Torsion Process was applied to an extruded hypereutectic Al–Si alloy. Mechanical properties of specimens which were unprocessed and processed with 20 revolutions at 473 K were investigated through the tensile test and upset test. Tensile test was carried out at R. T. to 573 K with 3 initial strain speed conditions. Upset test was carried out at R. T. and 473 K. As a result, tensile strength of processed specimen is increased at R. T. and 373 K. The initial strain speed affects the tensile strength at high temperature; low strain speed decrease the tensile strength compared with unprocessed specimen. Total elongation of processed specimen is increased more than twice as unprocessed specimen. Local elongation is increased at high temperature with low strain speed. Flow stress of processed specimen is higher than unprocessed specimen. Limit upset ratio of processed specimen is higher than unprocessed specimen tested at 473 K.
