The Advancement of 7XXX Series Aluminum Alloys for Aircraft Structures: A Review

Abstract

7XXX series aluminum alloys (Al 7XXX alloys) are widely used in bearing components, such as aircraft frame, spars and stringers, for their high specific strength, high specific stiffness, high toughness, excellent processing, and welding performance. Therefore, Al 7XXX alloys are the most important structural materials in aviation. In this present review, the development tendency and the main applications of Al 7XXX alloys for aircraft structures are introduced, and the existing problems are simply discussed. Also, the heat treatment processes for improving the properties are compared and analyzed. It is the most important measures that optimizing alloy composition and improving heat treatment process are to enhance the comprehensive properties of Al 7XXX alloys. Among the method, solid solution, quenching, and aging of Al 7XXX alloys are the most significant. We introduce the effects of the three methods on the properties, and forecast the development direction of the properties, compositions, and heat treatments and the solution to the corrosion prediction problem for the next generation of Al 7XXX alloys for aircraft structures. The next generation of Al 7XXX alloys should be higher strength, higher toughness, higher damage tolerance, higher hardenability, and better corrosion resistance. It is urgent requirements to develop or invent new heat treatment regime. We should construct a novel corrosion prediction model for Al 7XXX alloys via confirming the surface corrosion environments and selecting the accurate and reliable electrochemical measurements.

Corrosion Behaviour of High-Strength Al 7005 Alloy and Its Composites Reinforced with Industrial Waste-Based Fly Ash and Glass Fibre: Comparison of Stir Cast and Extrusion Conditions

“…7XXX series Al alloy possesses intrinsic properties such as high strength-to-density ratio, high-specific stiffness, and toughness characteristics making it an ideal candidate material for structural parts in automotive and aerospace applications [16,17]. The addition of reinforcement (organic, inorganic, industrial and agriculture waste, carbides, nitrides, oxides, CNTs, compounds) to aluminium matrix resulted in multiphase materials (composite materials) which improve the specific properties and attract engineering applications [18][19][20][21].…”

“…The above literature review confirms that limited studies have been carried out with industrial wastes as potential reinforcement materials for fabricating composites, although reinforcement particles offer beneficial properties. Al 7XXX series alloys are ultra-high-strength materials and therefore 70% of materials are used for structural applications in aircraft [16,50]. It was observed that 60% of structural parts are fabricated viz.…”

“…It was observed that 60% of structural parts are fabricated viz. extrusion, 28% by rolling, 7% by forging and 5% by casting routes [16]. However, next-generation materials need to enhance the hardenability, damage tolerance and corrosion resistance in Al 7XXX alloys [16,51].…”

“…extrusion, 28% by rolling, 7% by forging and 5% by casting routes [16]. However, next-generation materials need to enhance the hardenability, damage tolerance and corrosion resistance in Al 7XXX alloys [16,51]. Although aluminium material possesses good mechanical properties, it becomes corroded rapidly [52].…”

Machining of Inserts with PCD Cutting-Edge Technology and Determination of Optimum Machining Conditions Based on Roundness Deviation and Chip-Cross Section of AW 5083 AL-Alloy Verified with Grey Relation Analysis

“…The applications of PCD cutting materials are mainly in turning all pure nonferrous metals and nonferrous materials with little or no abrasive filler content [9]. Among the most commonly used nonferrous materials are aluminum alloys, which are used not only in mechanical engineering but also in many other industries [10].…”