PURPOSE: To obtain a heat resistant cast steel with superior creep rupture strength, thermal shock resistance, carburization resistance, etc. at high temp. by adding prescribed percentages of C, Si, Mn, Cr, Ni, W, N, Ti, Al, B and Cu.

CONSTITUTION: This heat resistant cast steel consists of, by weight, 0.3W0.6% C, ≤2.0% Si, ≤2.0% Mn, 20W30% Cr, 30W40% Ni, 0.5W5.0% W, 0.04W0.15% N, 0.04W0.5% Ti, 0.02W0.5% Al, 0.0002W0.004% B, ≤3.0% Cu and the balance essentially Fe. The cast steel is superior to a conventional HP material contg. W or other material in said characteristics at high temp., so it withstands well severe conditions during use as the material of an ethylene cracking tube, etc. in the petrochemical industry.