Improvement of Microstructure and Tensile Properties of Cast Iron by Semi-Solid Casting

Abstract

  The microstructure and tensile properties of cast iron obtained by semi-solid casting were investigated under the conditions of chilled-cooling, air-cooling and furnace-cooling respectively. The primary solid particles decreased in size with stirring. The remaining liquid transformed into fine ledeburite structures under chilled-cooling. Fine graphite particles were found throughout the heat treated semi-solid cast iron specimens. The tensile strength and elongation of the specimens were 383 MPa, 3.4 % and 414 MPa, 4.1 % at the stirring speeds of 10 and 16.7 rotations per second over respectively. The tensile properties obtained by the semi-solid casting were improved comparing with the ordinary casting samples. The microstructure and tensile properties of semi-solid cast iron were found to differ considerably depending on the cooling conditions.