Automatic Submerged ARC Welding With Metal Power Additions to Increase Productivity and Maintain Quality
NEWPORT NEWS SHIPBUILDING VA
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This paper presents the results of an SP-7 Welding Panel research and development project recently completed by Newport News Shipbuilding. The focus of this project was directed toward the evaluation, testing, and qualification of Automatic Submerged Arc Welding SAW-AU with metal powder additions for shipyard use. Metal powder additions provide an increase in deposition rate pounds of weld metal deposited per hour without an accompanying increase in heat input kilojoules per inch , and also provides a finer heat affected zone grain structure and narrower heat affected zone than conventional SAW-AU. Higher deposition rates, when obtained by higher heat input, can degrade the mechanical properties of the weld and adjacent base metal. Metal powder additions can produce quality welds with lower actual heat input joining either mild steel or quenched and tempered steel HY-80 , in substantially reduced time. The project consisted of both carbon steel and HY-80 test weldments using one-sided, double-bevel, and fillet joint designs at several heat inputs and powder-to-wire ratios. Nondestructive testing included magnetic particle, ultrasonic, and radiographic inspections. Destructive testing included tensiles, Charpy V-retch impacts, dynamic tear impacts, side bends, hardness surveys, and explosion testing. It is concluded that controlled metal powder additions are indeed a production concept that can reduce shipbuilding costs through increased deposition rates and reduced constables costs while, at the same time, maintaining or improving quality.
- Marine Engineering
- Couplers, Fasteners and Joints