Patent ID: 7326307

Claim:
A heat resistant cast steel having good thermal fatigue resistance, consisting essentially of, in weight percent, C: 0.2-0.42%, Ni: 8.0-45.0%, Cr: 15.0-30.0%, W: up to 10% and Nb: 0.5-3.0%, provided that [%C]-0.13[%Nb] is in the range of 0.05-0.95%, and the balance being Fe and inevitable impurities, contents of carbides in the steel being, in atomic percent, MC carbides 0.5-3.0% and M 23 C 6 carbides 0.5-10%, the matrix consisting essentially of an austenitic phase mainly composed of Fe—Ni—Cr, mean coefficient of thermal expansion in the range from room temperature to 1050° C. being up to 20.0×10 −4 , and tensile strength in the temperature range up to 1050° C. being 50 MPa or higher.