DEVELOPMENT OF A NEW NI-BASE SUPERALLOY FOR INDUSTRIAL GAS-TURBINE COMBUSTOR BY STATISTICAL ALLOY DESIGN METHOD

A new Ni-base superalloy has been developed for gas turbine combustor. In the first stage, multiple regression analysis was conducted on the published material data of superalloys. The eatimation equations were established to estimate the mechanical properties such as stress rupture strength and tensile properties, and physical properties such as density and thermal conductivity. Alloy design program by statistical method was made to select the alloy chemical compositions which will satisfy the requirements of structural design. By means of this alloy design method, 22%Cr-8%Co-9%Mo-3%W-1%Al-0.3%Ti-Ni base alloy (%:mass%) was set up for combustor superalloy. The superalloy plates using these alloy elements were manufactured by vacuum induction and remelting process weighing 2000 kg. The mechanical and physical properties were examined on those plates, and it is confirmed that these estimated values by alloy design coincide with the testing measured values. As above test results, it is considered that the statistical alloy design is useful for developing new superalloys. The new Ni-base superalloy also has good workability, good mechanical and physical properties for industrial gas turbine combustor.