2001 Volume 42 Issue 7 Pages 1385-1391
Fe–3%C–4%Si alloys were melted and solidified under various cooling rates and pressures up to 1000 MPa using a piston-cylinder type high pressure apparatus. Carbide eutectic was observed in the inner region of the specimens slowly cooled under a pressure of about 800 MPa. The observed transition from graphite eutectic (Gray) to carbide eutectic (White) was explained by the pressure dependence of the stable and metastable eutectic temperatures. Solidification analysis involving the pressure dependence of eutectic temperatures agreed well with the observed chill fraction. The effective pressure for Gray to White transition was estimated to be more than 200 MPa for commercial grade cast irons. From the stress analysis for cylindrical castings having different sizes, it was suggested that the maximum pressure generated during solidification depends on the strength of outer solidified shell and can be greater in spheroidal graphite cast iron than in flake graphite cast iron.