Effect of Cryogenic Treatment on Mechanical Properties of Aluminium Alloy AA2014
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ORIGINAL CONTRIBUTION
Effect of Cryogenic Treatment on Mechanical Properties of Aluminium Alloy AA2014 M. K. Chaanthini1 . M. Govindaraju1 . Sanjivi Arul1
Received: 20 July 2020 / Accepted: 2 October 2020 The Institution of Engineers (India) 2020
Abstract AA2014 is a high-strength Al-Cu alloy which is used for highly stressed components in aircraft fuselage, wing covers and military truck frames due to their excellent strength-to-weight ratio, and its properties are usually enhanced by further heat treatment. In this work, the conventional heat treatment process is replaced with shallow cryogenic treatment (SCT) with eight different soaking hours for enhancing the mechanical properties and followed by a tempering process at 160 C for 18 h. The dislocation effect due to SCT produces volume contraction and grain rotations and shrinking the vacancies and micropores, present in the matrix. Due to the metallurgical behaviour of the strengthening precipitates Theta(h) phase (CuAl2) and the insoluble particles which are finely dispersed along the grain boundaries of the matrix during the tempering process, results in higher tensile strength, % elongation and fracture toughness. The maximum percentage improvement in microhardness, ultimate tensile strength, % elongation, fracture toughness and wear rate are 40%, 1.28%, 10%, 23% and 48%, respectively, for 18 h of shallow cryogenic treatment, and the property varies for different soaking hours. With these improvements, AA2014 can provide better mechanical properties than the recently developed aluminium alloys with reduced cost. Keywords AA2014 Shallow cryogenic treatment Dry ice Tempering
& Sanjivi Arul [email protected] 1
Department of Mechanical Engineering, Amrita School of Engineering, Amrita Vishwa Vidyapeetham, Coimbatore, India
Introduction Aluminium alloys find their application in structural components, space and automotive applications due to low density, strength-to-weight ratio and corrosion resistance. Aluminium alloys can be heat-treatable and non-heattreatable. For automotive and aerospace applications, heattreatable alloys such as 2xxx, and 7xxx series are being used. AA2014 is one of the commercially used highstrength Al-Cu alloys, and it has various tempered forms, namely 2014 T4, 2014 T451, 2014 T651, 2014 T6. Among all the 2014 grades, AA2014 T6 is mostly used in aircraft structural industries due to its higher mechanical properties and also in military vehicles and weapons where the components are subjected to high stress [1]. The properties of AA2014 are generally enhanced by micro or nanoparticles reinforcement, heat treatment processes, cryogenic process, friction stir welding process and also some conventional metal forming processes. AA2014 is reinforced on the surface with SiC particles, using gas tungsten arc as heat source [1] to improve the hardness and wear properties; also with Sic and fly ash for 5% and 10% by weight, which increases the ultimate tensile strength, yield strength and impact strength as the weight % increased
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