Fracture Toughness of Plain and Welded 3-In.-Thick Aluminum Alloy Plate
The plane-strain fracture toughness, , of 3-in. 5083-H321, 5086-H32, 6061-T651, and 7005-T6351 plate and welds in the 5083, 6061, and 7005 plate have been evaluated in tests carried out in accordance with ASTM Test for Plane-Strain Fracture Toughness of Metallic Materials (E 399-72). Valid values of could be obtained only for the 7005-T6351 plate in all orientations. Both 5083-H321 and 5086-H32 are so tough that even 3-in.-thick specimens did not provide adequate restraint to permit valid measurements of , and in most tests of 6061-T651 there was excessive plasticity masking a measurement. From criteria that consider the load-carrying capability of the precracked fracture-toughness specimen and the yield strength, the alloys and tempers rate in the following order: 5086-H32 (toughest) 5083-H321 7005-T6351 6061-T651 However, the 7005-T6351 appears to provide the best combination of strength and toughness. Valid values of could not be obtained for most welds, primarily because of their very high toughness, and because of the problem in precracking resulting from the residual stresses from welding. Overall comparisons indicate that (a) welds of the recommended filler alloys are as tough as or tougher than the parent material, and (b) 5039 and 5356 welds are generally tougher than 4043 welds, either as-welded or heat-treated and aged after welding.
fracture properties, mechanical properties, crack propagation, aluminum alloys, fracture strength, weldments
Nelson, F. G.
Senior engineer, Alcoa Laboratories, New Kensington, Pa.
Kaufman, J. G.
Manager, Alcoa Laboratories, New Kensington, Pa.
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