MECHANICAL CONSIDERATIONS IN FRACTURE CHARACTERIZATION OF NARROW GAP WELDMENTS.
NAVAL RESEARCH LAB WASHINGTON D C
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The Dynamic Tear DT test provides a reliable measurement of fracture toughness under limit severity mechanical conditions. In this investigation, the DT test was used to characterize the fracture toughness for a weldment of 2-in.-thick A-543 plate prepared by the automatic Narrow-Gap N-G welding process. The DT test specimen was modified through the use of side grooves. Fracture toughness of the weld metal was found to be dependent upon welding position the flat 1200 and near vertical 0200 weld positions produce high upper shelf energy values equivalent to that of the plate metal, while the 0400 near vertical and 0600 overhead positions indicate a shelf level toughness approximately one-half that of the plate. Results of 58-in. DT tests were consistent with values from full-thickness, 2-in. DT specimens. The C sub v test produced a misleading indication of the transition temperature range and the temperature at which the upper shelf, full ductility develops. The uniquely limited width of the N-G weld enhanced the fracture toughness of the weldment in the transition temperature range and on the upper shelf when the crack tip plastic zone size exceeded the weld zone and entered the A-543 plate. This increased the resistance to fracture propagation through involvement of the tough plate metal. Author
- Couplers, Fasteners and Joints