P. R. Dungore, A. A. Agnihotri, Jawaharlal Nehru Aluminium Research Development and Design Centre, Nagpur, India
Heat treatment is an integral part of aluminum alloy processing. The full potential of high strength and medium strength aluminum alloys can be realized only after the adoption of proper heat treatment practices. A myriad of procedures are available and recommended depending on the properties desired and end use applications of the alloy. Advances in special heat treatment procedures adopted for the 2XXX and the 7XXX family of aerospace alloys are detailed. Special emphasis is laid on the structure property relationships. Special treatments used to improve fracture toughness, Stress corrosion cracking and corrosion resistance are explained using microstructural evaluation (SEM and TEM)and mechanical testing. Alloys 7475 and AA 2219 are vital for the Indian Space program. Advanced heat treatment procedures for these two alloys are dealt with in greater detail.
Summary: Processing of strategic aerospace aluminium alloys is an important step prior to the development of any aircraft or space vehicle. Heat treatment plays a crucial role in this developmental stage. Aluminum alloys are very sensitive to heat treatment schedules. Hence proper care needs to be exercised during very step of the heat treatment process (Solution treatment, quenching and ageing) to ensure that the full potential of these alloys is realised.
