Low thermal expansion cast steel and method of production of same

Abstract

An object of the present invention is to provide a low thermal expansion cast steel having sufficient strength even at a high temperature and a low coefficient of thermal expansion. The low thermal expansion cast steel of the present invention is obtained by suitably heat treating a cast steel comprising, by mass %, C: 0 to 0.10%, Si: 0 to 1.00%, Mn: 0 to 1.00%, Co: 13.00 to 17.50%, Ni satisfying −3.5×% Ni+118≤% Co≤−3.5×% Ni+121 (% Ni and % Co respectively represent the contents of Ni and Co (mass %)), and a balance of Fe and unavoidable impurities so that the 0.2% proof stress in a tensile test at 400° C. becomes 100 MPa or more, the average coefficient of thermal expansion at 25 to 350° C. becomes 6.0 ppm/° C. or less, and the Curie temperature becomes 350° C. or more.

Dependencies are inferred from the claim text.