Patent attributes
Disclosed is a heat resistant cast steel having not only good heat resistance but also good thermal fatigue resistance, which is suitable as the material for engine parts, particularly, such as exhaust gas manifold and turbo-housing, which are repeatedly exposed to such a high temperature as 900° C. or higher. The heat resistant cast steel comprises, by weight percent, C: 0.2-1.0%, 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]: 0.05-0.95%, the balance being Fe and inevitable impurities, and the cast structure contains dispersed therein, by atomic percent, MC-type carbides: 0.5-3.0% and M23C6-type carbides: 0.5-10.0%. The matrix of the steel is an austenitic phase mainly composed of Fe—Ni—Cr and the steel has the mean coefficient of thermal expansion in the range from room temperature to 1050° C. up to 20.0×10−4 and a tensile strength in the temperature range up to 1050° C. 50 MPa or higher.
