Rivet Qualification of Aluminum Alloy 7050.
Final technical rept. Feb 75-Jun 76,
ALUMINUM CO OF AMERICA ALCOA CENTER PA ALCOA LABS
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Manufacturing methods were established for the production of aluminum alloy 7050 aircraft-size rivets. Strength, formability and corrosion tests were conducted on wire to establish the aging practices to be applied to the rivets. The purity level had no noticeable effect on rivet fabrication, strength properties, formability or resistance to stress-corrosion cracking SCC of the wires. The rivets, in 332, 316 and 38-in. diameter sizes, were given second step agings of 8 hours at 345, 350 and 355 F. Driving and hole-fill evaluations, static tests of lap-shear joints, fatigue tests of high load-transfer joints and SCC tests were conducted using the 7050 rivets. The driving and hole-fill quality, the static strength and resistance to SCC for 7050 alloy rivets equals or exceeds that of 2024-T31 ice-box rivets. Driven shear strength values were at least 15 per cent greater than that typically found for 2024-T31 rivets. The fatigue strength of joints with 7050 rivets was less than similar joints containing 2024-T31 rivets. A production aging practice is recommended to place the 7050 rivets in the T73 temper. Residual stress around the rivet hole can affect the resistance to stress-corrosion cracking of the material being joined.
- Properties of Metals and Alloys
- Couplers, Fasteners and Joints