Patent ID: 9284633
Filing Date: 2016-03-15
CPC Classification: C21D,C22C

Claim Text:
1. A method of manufacturing a heat resistant cast steel comprising, in percent by mass, C: 0.05-0.15, Si: 0.03-0.2, Mn: 0.1-1.5, Ni: 0.1-1, Cr: 8-8.7, Mo: 0.2-1.5, V: 0.1-0.3, Co: 2.7-5, W: 0.1-5, N: 0.005-0.03, Nb: 0.01-0.2, B: 0.004-0.015, Ti: 0.01-0.1, and Fe, the method comprising: melting raw materials, refining and degassing the melted raw materials, pouring the melted raw materials into a predetermined mold to form a shape, performing an annealing treatment at a temperature of 1000 to 1150° C., cooling the annealed raw materials at a cooling rate of 20 to 60° C./hour, performing a normalizing treatment at a temperature of 1000 to 1200° C., cooling the normalized raw materials at a cooling rate of 100 to 600° C./hour in a center part of the heat resistant cast steel, performing a first stage tempering treatment at a temperature of 500 to 700° C., cooling the first-stage tempered raw materials at a cooling rate of 40 to 100° C./hour in the center part of the heat resistant cast steel, performing a second stage tempering treatment at a temperature of 700 to 780° C., and cooling the second-stage tempered raw materials at a cooling rate of 20 to 60° C./hour.