1991 Volume 77 Issue 5 Pages 707-714
In order to develop a new low alloy steel for gas turbine rotor disk, considerable studies have been performed.
The targets of a new low alloy steel development for disk are to have excellent stress rupture strength which is not required to take account of creep below 400°C, and to have excellent both high temperature strength (Yield strength at 400°C is higher than 60 kgf/mm2) and fracture toughness (FATT is lower than +40°C) at bore of disk.
The effect of chemical composition on mechanical properties and the heat treatment characteristics of low alloy steel were investigated. As a result, the 21/4Cr-Mo-V-Nb steel containing low silicon manufactured by VCD or ESR process was found to have the best performance for large size disk.
Based on the above results, the 21/4Cr-Mo-V-Nb steel disk for turbine was produced by commercial base. Tensile, impact and metallurgical tests were conducted on this disk, and it is confirmed that this disk has excellent yield strength and impact properties at both rim and bore.
