The University of Texas System

Robert W Carnes

Paul W Haase

Robert S Hudson

Steven P Nichols

Michael W Harville

The present invention discloses methods and apparatus for joining of two workpieces. The present invention includes special preparation of the joining ends of the two workpieces to be joined. Methods of the present invention include delivering a high current, low voltage pulse to a pair of workpieces to be joined while applying and maintaining a constantly high load on said workpieces to thereby join the workpieces.

Method and apparatus for joining metals

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.

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Austin, TX, United States of America

Robert W Carnes