2024 aluminium alloy
2024 aluminium alloy is an aluminium alloy, with copper as the primary alloying element. It is used in applications requiring high strength to weight ratio, as well as good fatigue resistance. It is weldable only through friction welding, and has average machinability. Due to poor corrosion resistance, it is often clad with aluminium or Al-1Zn for protection, although this may reduce the fatigue strength. In older systems of terminology, 2XXX series alloys were known as duralumin, and this alloy was named 24ST. 2024 is commonly extruded, and also available in alclad sheet and plate forms. It is  not commonly forged (the related 2014 aluminium alloy is, though). Basic properties. Aluminium alloy 2024 has a density of 2.78 g/cm (0.1  lb/in), electrical conductivity of 30% IACS, Young's Modulus of 73 GPa (10.6 Msi) across all tempers, and begins to melt at . 2024 aluminium alloy's composition roughly includes 4.3–4.5% copper, 0.5–0.6% manganese, 1.3–1.5% magnesium and less than a half a percent of silicon, zinc, nickel, chromium, lead and bismuth. Chemical composition. The alloy composition of 2024 is: Mechanical properties. The mechanical properties of 2024 depend greatly on the temper of the material. 2024-O. 2024 -O temper aluminium has no heat treating. It has an ultimate tensile strength of , and maximum yield strength of no more than . The material has elongation (stretch before ultimate failure) of 10–25%, this is the allowable range per applicable AMS specifications. 2024-T3. T3 temper 2024 sheet has an ultimate tensile strength of and yield strength of at least . It has an elongation of 10–15%. 2024-T4. Solution treated and naturally aged. 2024-T5. Cooled from hot working and artificially aged (at elevated temperature) 2024-T351. T351 temper 2024 plate has an ultimate tensile strength of and yield strength of  . It has elongation of 20%. Uses. Due to its high strength and fatigue resistance, 2024 is widely used in aircraft, especially wing and fuselage structures under tension. Additionally, since the material is susceptible to thermal shock, 2024 is used in qualification of liquid penetrant tests outside of normal temperature ranges.