ALUMINUM ALLOY 2624-T351 and 2624-T39 High Damage Tolerance Plate DESCRIPTION APPLICATIONS Alcoa developed aluminum alloy AA 2624 for use in aerospace plate applications requiring very high damage tolerance properties. Compared to alloy 2024 and 2324 plate properties, 2624 offers improved fracture toughness and fatigue resistance with similar strength and corrosion resistance. Alloy 2624 plate was developed to replace alloy 2024 and 2324 in applications requiring moderate or high strength and the highest levels of damage tolerance such as lower wing panels and other tension-dominated aerospace structures. The machining and fabrication characteristics of 2624 plate are the same or very similar to that of other 2x24 plate products. Alloy 2624 is available in the T351 and the higher strength T39 temper. The available thickness range for 2624-T351 plate is 0.5 to 1.5 inches (12.7 to 38.1 mm). The available thickness range for 2624-T39 plate is 0.75 to 1.5 in. (19.0 to 38.1 mm). COMMERCIAL STATUS Alcoa 2624 plate has been supplied commercially to customer and industry specifications since 1998. It is currently specified for use on lower wing panels on various aircraft worldwide, from business jets to large commercial aircraft. 2624-T351 is covered by AMS 4464 and 2624-T39 is covered by AMS 4473. Material design allowables are available for both tempers in the MMPDS Handbook. CHEMICAL COMPOSITION Chemical Composition Limits • AA 2624 (Wt.%)* Cu Mg Mn Cr Zn Ti Fe Si Al 3.8 – 4.3 1.2 – 1.6 0.45 – 0.7 0.05 max 0.15 max 0.10 max 0.08 max 0.08 max Remainder Static Properties 2624-T351 and 2624-T39 Plate • Minimum Values (S or A-Basis) Alloy/Temper Thickness, Inch (mm) Tensile Strength, Ftu, ksi (MPa) Tensile Yield, Fty, ksi (MPa) Elongation, %, 4D Tension Modulus, Msi (GPa) 2624-T351 (AMS 4464) Orient. 2024-T7351 (AMS 4037) 2624-T39 (AMS 4473) 2324-T39 (S or A estimate*) 0.500 – 1.000 1.001 – 1.500 0.500 – 1.000 1.001 – 1.500 0.750 – 1.500 (12.70 – 25.40) (25.42 – 38.10) (12.70 – 25.40) (25.42 – 38.10) (19.00 – 38.10) 0.750 – 1.500 (19.00 – 38.10) L 63 (434) 62 (427) 63 (434) 62 (427) 68 (469) 68 (469) LT 65 (448) 64 (441) 63 (434) 62 (427) 71 (490) 71 (490) L 48 (331) 47 (324) 48 (331) 47 (324) 62 (427) 63 (434) LT 44 (303) 44 (303) 42 (290) 42 (290) 58 (400) 58 (400) L 16 16 na na 11 10 LT 15 15 8 7 9 8 10.3 (71.0) 10.3 (71.0) 10.3 (71.0) 10.7 (73.7) *2324-T39 minimums calculated in accordance with MMPDS guidelines, but not submitted or approved by MMPDS CONTACT AND PROCUREMENT For additional information on 2624-T351 or 2624-T39 plate, contact your local Alcoa Sales Account Manager. FATIGUE AND DAMAGE TOLERANCE PROPERTIES The S-N fatigue, fatigue crack growth resistance and fracture toughness of 2624-T351 and 2624-T39 plate are superior to those of 2024-T351 and 2324-T39 plate, which were the industry choices for applications requiring moderately high strength and high damage tolerance. FCG Curves 1.0E-02 1.0E-03 2624-T351 2624-T39 Orient. KIc, KQ Minimum ksi√in (MPa√m) Kapp* ksi√in (MPa√m) L-T 48 (53) 102 (112) T-L 47 (52) L-T 46 (50) T-L 42 (46) L-T 37 (41) T-L 34 (37) L-T 38 (42) T-L 36 (40) 2024-T351 2324-T39 da/dN (in/cycle) Fracture Toughness • 2624-T351 and 2624-T39 Plate • Typical Values Alloy/Temper L-T Orientation R=0.1, RH>90% Frequency=25 Hz M(T), W= 4 in. 113 (124) 1.0E-04 1.0E-05 2024-T351 1.0E-06 97 (106) 2324-T39 2624-T351 2624-T39 98 (108) 1.0E-07 1 10 K (ksi in) *Kapp from 16 in. (406 mm) wide M(T) panel Plane Stress R-Curves Spectrum FCG 180 Large Aircraft Lower Wing Spectrum L-T Orientation 2.5 140 2.0 1.5 2624-T351 2624-T39 2024-T351 2324-T39 1.0 0.5 0 1000 2000 3000 4000 5000 120 100 80 2624-T351 2624-T39 2024-T351 2324-T39 60 40 20 M(T), W= 7.87 in., thick.= 0.47 in., RH > 90%, Freq. ~ 10 Hz 0.0 L-T Orientation 160 KR (ksi in) Half Crack Length, a (inch) 3.0 100 6000 7000 0 Number of Flights M(T) Panel, W = 16 in., 2ao= 4 in., thickness = 0.25 in. 0.0 0.5 1.0 1.5 2.0 aeff (inch) CORROSION RESISTANCE The corrosion resistance of 2624-T351 and 2624-T39 plate is similar to that of 2024-T351 and 2324-T39 plate. The exfoliation rating of these products typically ranges from EB to ED (ASTM G34 rating) after two years of seacoast exposure. Their SCC resistance (ASTM G47) in the LT direction typically ranges from 22 to 29 ksi (150 to 200 MPa). The same or similar corrosion protection measures currently used on 2024-T351 and 2324-T39 parts should be applied to 2624-T351 and 2624-T39. ALCOA AEROSPACE AND AUTOMOTIVE PRODUCTS P.O. BOX 8025 • BETTENDORF, IOWA 52722 • 1-800-523-9596 • www.alcoa.com Product specifications are subject to change without notice. ©2016 Alcoa Inc. 1/16