PURPOSE: To obtain a heat resisting cast steel having an excellent productivity characteristic as well as performance and durability characteristic by casting a cast steel consisting of specifically composed C, Si, Mn, P, S, Cr, Mo and Fe then subjecting the cast steel to an annealing treatment to decompose the carbide in the base structure.
CONSTITUTION: The cast steel having the compsn. consisting of 0.5W2.5wt% C, 1.5W4.5% Si, ≤0.7% Mn, ≤0.05% P, ≤0.1% S, 5.0W14.0% Cr, 2.0W6.5% Mo and the balance substantially Fe is cast and is then subjected to the ordinary annealing treatment consisting in about 900W950°C×0.5hr of an austenitization treatment, then furnace cooling down to about 680W750°C and holding and cooling at and to about 680W750°C×0.5hr. The base is converted to the ferrite structure and the carbide in the above-mentioned structure without contg. graphite is converted to the primary carbide crystallized in the dendrite state and the finely dispersion-precipitated granular secondary carbide. The heat resisting cast steel having the excellent productivity characteristics including castability, machinability, low cost characteristic, etc. as well as the performance such as resistance to heat and oxidation and durability characteristic is thus obtd.