METHOD FOR MANUFACTURING TIAL ALLOY CASTING MATERIAL, TiAl ALLOY CASTING MATERIAL, TURBINE BLADE FOR JET ENGINE, AND TURBINE WHEEL

Abstract

A method for manufacturing a TiAl alloy casting material includes a melting step of melting a raw material including Ti and Al to prepare a molten metal; a deoxidation material adding step of adding a deoxidation material including Ca to either or both of the raw material and the molten metal, the deoxidation material being added such that a Ca concentration in a total mass of the raw material and the deoxidation material is 0.2 mass % to 1.0 mass %; and a deoxidation step of heating the molten metal including the deoxidation material for maintaining a molten state to generate a fume including a reaction product of oxygen and Ca in the molten metal, so that the oxygen in the molten metal is removed.

1 . A method for manufacturing a TiAl alloy casting material, the method comprising:
 a melting step of melting a raw material including Ti and Al to prepare a molten metal;   a deoxidation material adding step of adding a deoxidation material including Ca to either or both of the raw material and the molten metal, the deoxidation material being added such that a Ca concentration in a total mass of the raw material and the deoxidation material is 0.2 mass % to 1.0 mass %; and   a deoxidation step of heating the molten metal including the deoxidation material for maintaining a molten state to generate a fume including a reaction product of oxygen and Ca in the molten metal, so that the oxygen in the molten metal is removed.   
     
     
         2 . The method for manufacturing a TiAl alloy casting material according to  claim 1 ,
 wherein the deoxidation material is an AlCa alloy.   
     
     
         3 . The method for manufacturing a TiAl alloy casting material according to  claim 1 ,
 wherein the melting step is a step of melting the raw material in an oxide ceramic crucible,   the deoxidation material adding step is either or both of a step of putting the deoxidation material into the oxide ceramic crucible together with the raw material and a step of adding the deoxidation material to the molten metal put into the oxide ceramic crucible, and   in the deoxidation step, the molten metal including the deoxidation material put into the oxide ceramic crucible is heated and melted.   
     
     
         4 . The method for manufacturing a TiAl alloy casting material according to  claim 1 ,
 wherein the deoxidation material adding step is a step of putting the deoxidation material into an oxide ceramic crucible installed in a vacuum melting furnace together with the raw material,   the melting step is a step of melting the raw material in the oxide ceramic crucible installed in the vacuum melting furnace under an Ar atmosphere after the deoxidation material adding step, and   in the deoxidation step, the molten metal including the deoxidation material is heated and melted in the oxide ceramic crucible installed in the vacuum melting furnace under the Ar atmosphere.   
     
     
         5 . The method for manufacturing a TiAl alloy casting material according to  claim 3 ,
 wherein the oxide ceramic crucible is installed in an atmospheric melting furnace under an air atmosphere,   the melting step includes a mold installation step of installing a wider opening portion of a funnel-shaped mold toward the oxide ceramic crucible to cover an opening portion of the oxide ceramic crucible, an atmosphere replacement step of supplying an Ar gas into the oxide ceramic crucible, and a heating step of heating the oxide ceramic crucible,   the deoxidation material adding step is either or both of a step of putting the deoxidation material into the oxide ceramic crucible together with the raw material and a step of adding the deoxidation material to the molten metal put into the oxide ceramic crucible via the funnel-shaped mold,   in the deoxidation step, the molten metal including the deoxidation material is heated and melted in the oxide ceramic crucible of which an opening portion is covered with the funnel-shaped mold, the fume in the oxide ceramic crucible is discharged via the funnel-shaped mold, and   after the deoxidation step, a casting step of turning the atmospheric melting furnace upside down in a state in which the oxide ceramic crucible and the funnel-shaped mold are integrated with each other, to pour the molten metal into the funnel-shaped mold from the oxide ceramic crucible and cool the molten metal is performed.   
     
     
         6 . The method for manufacturing a TiAl alloy casting material according to  claim 1 ,
 wherein the raw material includes either or both of TiAl alloy cutting chips and TiAl alloy casting scraps.   
     
     
         7 . A TiAl alloy casting material comprising:
 0.04 mass % to 0.10 mass % of oxygen and 0.01 mass % to 0.03 mass % of Ca.   
     
     
         8 . A TiAl alloy casting material comprising:
 31.9 mass % to 34.2 mass % of Al, 4.0 mass % to 5.4 mass % of Nb, 2.3 mass % to 3.0 mass % of Cr, 0.04 mass % to 0.12 mass % of oxygen, and 0.01 mass % to 0.07 mass % of Ca, with a balance being Ti and impurities.   
     
     
         9 . A turbine blade for a jet engine made of the TiAl alloy casting material according to  claim 7 . 
     
     
         10 . A turbine wheel made of the TiAl alloy casting material according to  claim 7 .