Ni-based superalloy part recycling method

A method for recycling a Ni-based single crystal superalloy part provided with an oxidation-resistant coating or a Ni-based single crystal superalloy part not provided with an oxidation-resistant coating, on a surface of a Ni-based single crystal superalloy substrate, the method comprising the steps of:

• melting and desulfurizing the Ni-based single crystal superalloy part at a temperature in a range from 1400° C. to 2000° C. to prepare a desulfurized Ni-based single crystal superalloy;
• and
• forming a recycled Ni-based single crystal superalloy part or a melting stock using the Ni-based single crystal superalloy,
• wherein
• in the step of desulfurizing the Ni-based single crystal superalloy part, the Ni-based single crystal superalloy part is desulfurized so that a sulfur content of the Ni-based single crystal superalloy part is 3 PPM or less, and
• in a case of directly forming the recycled Ni-based single crystal superalloy part, the method comprises the steps of:
• heating a casting mold for a recycled Ni-based single crystal superalloy part to have a temperature in a range from 1400° C. to 1600° C.;
• pouring the melted Ni-based single crystal superalloy into the casting mold for a recycled Ni-based single crystal superalloy part to grow the Ni-based single crystal superalloy;
• and
• removing the recycled Ni-based single crystal superalloy part from the casting mold for a recycled Ni-based single crystal superalloy part, and
• in a case of forming a recycled Ni-based single crystal superalloy part from a melting stock, the method comprises the steps of:
• pouring the melted Ni-based single crystal superalloy into a casting mold for a melting stock to form a melting stock;
• removing the melting stock from the casting mold for a melting stock;
• and
• producing a Ni-based single crystal superalloy part from the melting stock.

A method for recycling a Ni-based unidirectionally solidified superalloy part provided with a thermal barrier coating containing at least a ceramic on a surface of a Ni-based unidirectionally solidified superalloy substrate, the method comprising the steps of:

• melting and desulfurizing the Ni-based unidirectionally solidified superalloy part at a temperature in a range from 1400° C. to 2000° C. to prepare a desulfurized Ni-based superalloy;
• and
• forming a recycled Ni-based unidirectionally solidified superalloy part or a melting stock using the Ni-based unidirectionally solidified superalloy,
• wherein
• in the step of desulfurizing the Ni-based unidirectionally solidified superalloy part, the Ni-based unidirectionally solidified superalloy part is desulfurized so that a sulfur content of the Ni-based unidirectionally solidified superalloy part is 3 PPM or less, and
• in a case of directly forming the recycled Ni-based unidirectionally solidified superalloy part, the method comprises the steps of:
• heating a casting mold for a recycled Ni-based unidirectionally solidified superalloy part to have a temperature in a range from 1400° C. to 1600° C.;
• pouring the melted Ni-based superalloy into the casting mold for a recycled Ni-based unidirectionally solidified superalloy part to grow the Ni-based unidirectionally solidified superalloy;
• and
• removing the recycled Ni-based unidirectionally solidified superalloy part from the casting mold for a recycled Ni-based unidirectionally solidified superalloy part, and
• in a case of forming a recycled Ni-based unidirectionally solidified superalloy part from a melting stock, the method comprises the steps of:
• pouring the melted Ni-based unidirectionally solidified superalloy into a casting mold for a melting stock to form a melting stock;
• removing the melting stock from the casting mold for a melting stock;
• and
• producing a Ni-based unidirectionally solidified superalloy from the melting stock.