Method for determining and controlling the cooling rate for metal alloys in an electrical resistance welding process
The system of the present invention includes a homopolar generator, a hydraulic uniaxial press to hold the metal alloys to be welded, and electrical connections set at selected distances from the weld interface to provide a desired cooling rate for metal alloys being welded. A method is disclosed for determining a cooling rate for a metal alloy pipe in an electrical resistance welding process in a homopolar welding system following the resistive heating of a weld interface by discharging energy from a homopolar generator through electrodes attached to each of first and second pipes to form a welded pipe segment. The temperature of the welded pipe segment is measured at periodic time intervals to determine a cooling rate for the welded pipe segment. A desired range for the cooling rate may be determined by adjusting the electrode gap for repeated samples and analyzing the resulting metallurgical properties for each sample. In a further aspect, a method is disclosed for controlling the cooling rate of metal alloy pipe by varying the electrode gap to provide a desired cooling rate following resistive heating of the weld interface and allowing the welded pipe segment to cool at the desired cooling rate.