Abrégé

This invention is concerned with the production of directionally solidified castings or ingots to eliminate casting defects such as macrosegregation and misoriented grain defects that occur in the blades for jet engines and industrial gas turbines. The mechanism of the occurrence of the above casting defects was clarified by the computer simulation system developed by this inventor, and it was found that, by strongly cooling the solid phase region and applying an axial static magnetic field, the heat pulses at the solidification interface due to convection of the liquid phase can be suppressed, and harmful lateral liquid flow in the solid-liquid coexisting phase can be suppressed by the synergistic effect of these two measures. This eliminates casting defects such as macrosegregation and misoriented grain defects, also refines the microstructure to produce high-quality products with excellent mechanical properties (creep strength). Regarding the strength of the static magnetic field, it was found that there is a range where the macrosegregation becomes minimum in a relatively low magnetic field range. This makes it possible to keep the required magnetic strength low, which significantly reduces the price of expensive superconducting coils. In addition, productivity can be improved by increasing the withdrawal speed.

Classes IPC  ?

• B22D 27/04 - Action sur la température du métal, p. ex. par chauffage ou refroidissement du moule
• B22D 27/02 - Emploi d'effets électriques ou magnétiques
• B22D 27/00 - Traitement du métal dans le moule pendant qu'il est liquide ou plastique

Abrégé

In order to eliminate casting defects such as macro segregation and anisotropic crystal defects generated in a unidirectional solidification process for a blade used in a jet engine or a gas turbine for power generation, there was clarified the mechanism by which casting defects are generated, and there was ascertained that it is possible to suppress a heat pulse to the solidification interface due to liquid-phase convection, and to suppress adverse liquid-phase flow in a solid-liquid coexistence phase, by the synergistic effect of applying an axial-direction static magnetic field and forced cooling of a solid-phase region. Consequently, it is possible to produce a high-quality product having excellent mechanical properties (creep strength) by eliminating casting defects such as macro segregation and anisotropic crystal defects, and refining solidified structure. With regard to the intensity of the static magnetic field, there was found that, in a relatively low magnetic field region, there exists a region in which macro segregation is minimized Consequently, the required magnetic field intensity can be suppressed to a low intensity, and the cost of an expensive superconducting coil can be lowered significantly. Furthermore, productivity can be increased by the withdrawal speed.

Classes IPC  ?

• B22D 27/04 - Action sur la température du métal, p. ex. par chauffage ou refroidissement du moule

Abrégé

This invention provides a casting technique for manufacturing a high-quality casting free from macrosegregation defects. In the manufacture of an unidirectional solidified casting, or an ingot by a remelting method such as ESR, VAR or the like, attention has been drawn to a fluid phenomenon of a liquid phase within a solid-liquid coexistent phase during solidification, and very low-speed liquid phase fluidity between dendrites causative of macrosegregation formation could have been suppressed by applying a strong magnetic field to the whole solid-liquid coexistent phase, whereby macrosegregation defects such as freckles could have been suppressed.

Classes IPC  ?

• B22D 11/115 - Traitement du métal liquide en utilisant des moyens agitateurs ou vibrants en utilisant des champs magnétiques
• B22D 11/11 - Traitement du métal liquide

Abrégé

In the production of ingot by remelting technique, such as ESR or VAR, or unidirectionally solidified cast metal, with attention focused on the phenomenon of flow of liquid phase within solid/liquid coexistent phase during solidification, a strong magnetic field is applied to the whole of the solid/liquid coexistent phase to thereby inhibit any inter-dendrite liquid phase flow of extremely low velocity tending to cause macrosegregation occurrence and accordingly suppress any macrosegregation defects, such as freckles. Thus, there is provided a casting technology for production of high-quality cast product free from such macrosegregation defects.

Classes IPC  ?

• B22D 11/11 - Traitement du métal liquide
• B22D 11/115 - Traitement du métal liquide en utilisant des moyens agitateurs ou vibrants en utilisant des champs magnétiques