Program to Improve the Fracture Toughness and Fatigue Resistance of Aluminum Sheet and Plate for Aircraft Applications. Volume II.
Final technical rept. 1 Mar-1 Jul 74
REYNOLDS METALS CO RICHMOND VA METALLURGICAL RESEARCH DIV
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The fatigue crack growth rate FCGR characteristics of a 7000 series and a 2000 series alloy were evaluated. The bulk of the work was carried out on thermomechanically aged TMA RX725 Al-6Zn-2.5Mg-1.5Cu-.1 Zr and 2048 in the TMA and -T3E9 tempers respectively. Crack growth rate was reduced by either crack branching or deviation of the crack from the plane normal to the applied stress. Both experimental materials were found to be sensitive to environment high or low humidity even though they were resistant to exfoliation corrosion.. An inverse hyperbolic tangent model fitted the data well, but the parameters in the model did not lend themselves to characterizing FCGR material performance. It was concluded that significant benefits could be achieved by TMA processing.
- Metallurgy and Metallography