Weld repair of superalloy castings
View Patent ↗A method of repairing a void on a nickel or cobalt base superalloy investment casting by vibrating the casting for a time before repairing the void, vibrating the casting while filling the void wherein the void is filled by repeatedly making incremental weld deposits of a superalloy filler material in the void using pulsed gas tungsten arc welding, and impinging each incremental deposit with a cooling gas after each incremental weld deposit is made and before the next incremental weld deposit is made, and vibrating the casting for a time after the void is filled.
1. A method of repairing a void on a nickel or cobalt superalloy investment casting, comprising:
solution heat treating said casting,
clamping said casting on a welding table,
vibrating said table at a sub-harmonic frequency for a time before filling said void with a superalloy filler material,
vibrating said table at a sub-harmonic frequency while filling said void by repeatedly making incremental weld deposits of said superalloy filler material in said void using pulsed gas tungsten arc welding and impinging each incremental deposit with a cooling gas after each incremental weld deposit is made and before the next incremental weld deposit is made, and
vibrating said table at a sub-harmonic frequency for a time after said void is filled.
2. The method of claim 1 wherein said arc welding is conducted with a pulsed welding current.
3. The method of claim 2 wherein said welding current is pulsed in the range of 440 to 460 pulses per second.
4. The method of claim 2 wherein said welding current is controlled to have a background current in the range of 5 to 8 amperes and a pulse current in the range of 75 to 85 amperes.
5. The method of claim 1 wherein said cooling gas comprises compressed shop air directed at each incremental deposit for a period of time.
6. The method of claim 1 wherein said sub-harmonic frequency is in the range of 40 to 50 Hertz.