Method of manufacturing of a casted part or ingot of a metallic alloy attaining a minimal segragation in the casting process

Abstract

The present invention relates to a method of manufacturing of a casted part or ingot of a metallic alloy attaining a minimal segregation in the casting process, for alloys which are prone to segregate. The method can also be employed to refine the grain and microstructure of the obtained alloys. The method is especially interesting for Fe, Ti, Co or Ni based alloys. The method is very inexpensive and can be applied for the obtaining of very large cross-sections. An additional feature of the method is that it can be employed to capitalize impurities.

1 . A method of manufacturing a casted metallic alloy, wherein the casting process comprises the following steps:
 a) Adding to the melt of the metallic alloy at least 12 ppm of a nucleation promoter, and   b) Subjecting the melt of the metallic alloy to vibration with an acceleration of at least 1 m/s2 at least until the melt of the metallic alloy is below the theoretical melting point of the metallic alloy and/or until at least 10% solid phase is present, and/or   c) Bubbling to the melt of the metallic alloy a gas flow of at least 1 m3/min per ton of the melt of the metallic alloy, at least until the melt of the metallic alloy is below the theoretical melting point of the metallic alloy and/or until at least 10% solid phase is present   
     
     
         2 . The method of  claim 1 , wherein the nucleation promoter in step a) is selected from the group consisting on: Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ti and Si and mixtures thereof. 
     
     
         3 . The method of  claim 1 , wherein the nucleation promoter in step a) is selected from the group consisting on: Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu and mixtures thereof. 
     
     
         4 . The method of  claim 1 , wherein the nucleation promoter in step a) is selected from the group consisting on Ce, La, Sm, Y, Ne and/or Ge and mixtures thereof. 
     
     
         5 . The method according to  claim 1 , wherein the nucleation promoter in step a) consist on a mixture of La and at least one of Sc, Y, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ti and Si, characterized in that La is at least 40% of the total amount of the REEs. 
     
     
         6 . The method of  claim 1 , wherein the nucleation promoter in step a) consist on a mixture of Ce and at least one of Sc, Y, La, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ti and/or Si, characterized in that Ce is at least 40% by weight of the total amount of the REEs. 
     
     
         7 . The method of  claim 1 , wherein the nucleation promoter in step a) consist on a mixture of Nd and at least one of Sc, Y, La, Ce, Pr, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ti and/or Si, characterized in that Nd is at least 40% by weight of the total amount of the REEs. 
     
     
         8 . The method according to  claim 1 , wherein the nucleation promoter in step a) is in its ferro alloy and/or pure and/or oxide form and/or mixtures thereof. 
     
     
         9 . The method according to  claim 1 , wherein the nucleation promoter is added to the melt of the metallic alloy between 12 ppm and 3.4% by weight. 
     
     
         10 . The method according to  claim 1 , wherein steps b) and/or c) are applied at least until the melt of the metallic alloy reaches a temperature between 8K and 110 k below the theoretical melting temperature. 
     
     
         11 . The method according to  claim 1 , wherein the acceleration in step b) is between 1 m/s 2  and 32 m/s 2 . 
     
     
         12 . The method according to  claim 1 , wherein the gas flow in step c) is between 1 m 3 /min and 28 m 3 /min. 
     
     
         13 . The method according to  claim 1 , wherein the vibration in step b) is made using a magneto-restrictive generator. 
     
     
         14 . The method according to  claim 1 , wherein the amplitude used for vibration in step b) is at least 1 mm. 
     
     
         15 . The method according to  claim 1 , wherein the vibration frequency in step b) is between 8 and 60 Hz. 
     
     
         16 . The method of  claim 1 , wherein the bubbled gas in step b) is selected from Ar, N2, O2 and/or mixtures thereof. 
     
     
         17 . The method of  claim 1 , wherein the pressure of the bubbled gas in step c) is at least 2 bar. 
     
     
         18 . The method of  claim 1 , wherein the metallic alloy casted is a Fe, Ti, Co or Ni based alloy. 
     
     
         19 . The method of  claim 1 , characterized in that reduces the segregation levels for at least one component to less than 80%.