PLASMA ARC WELDING OF THIN MATERIALS.
Final technical rept. 1 Nov 66-31 May 67,
GENERAL MOTORS CORP INDIANAPOLIS IN ALLISON GAS TURBINE DIV
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Metallurgical evaluation and mechanical test data obtained on continuous fusion welding, both manual and mechanized, in AMS-5521, AMS-5504, AMS-5545, AMS-4901, and AMS-4911 resulted in quality and mechanical properties equivalent to welds made by the gas tungsten arc welding GTAW process. The simplicity of welding with the low amperage 0.1 to 10.0 amp dc plasma arc process has been recognized on test welds completed during the program. The collimated shape of the plasma arc makes the process relatively insensitive to arc length variations. An arc length change of or - 0.050 in. can be tolerated before weld appearance or penetration are affected under normal operating conditions using an argon atmosphere and relatively long arc lengths of 0.125 to 0.375 in. Particularly smooth and consistent edge welds are obtained to a degree not normally reached with the GTAW process. Fusion welding of simulated and actual production parts was completely satisfactory in material thicknesses to 0.030-in., producing weld appearance similar to the GTAW process with the advantages of simplified arc prepositioning and, starting with the pilot arc transfer system, insensitivity to arc length variations common in manual welding, and excellent low amperage arc stability. Arc spot welding results indicate additional development effort is required for a higher amperage power source and improved torch design permitting controlled pressure at the workpiece. Some arc spot welds were made meeting the strength requirement of MIL-W-27664 however, consistent acceptable nugget depression, weld contour repeatability, and weld quality were not possible. Author
- Manufacturing and Industrial Engineering and Control of Production Systems