TWI

Metallographic observations, hardness distribution measurements and fatigue tests were undertaken to investigate the discontinuity state related to the crack nucleation site in butt joints fabricated in 2024-T3 aluminium alloys (Al, 3.8-4.9%Cu, 1.2-1.8%Mg, 0.3-0.9%Mn) by friction stir welding. Micro indentation hardness testing was performed to measure hardness distribution in weld nugget, thermomechanically affected zone and HAZ. Specimens with tangentially blended fillets were prepared for fatigue tests and four types of surface finish (such as surface grinding and polishing) were used to evaluate the effect of surface conditions on crack nucleation site and fatigue life. Other issues discussed include lack of penetration defects and the dependence of fracture surface features on crack nucleation site.

7th International Symposium, 20-22 May 2008, 8B: Mechanical Properties, Paper 04