OPTIMIZING ALLOY COMPOSITION AND MECHANICAL PERFORMANCE OF 7075 ALUMINIUM ALLOY FOR LIGHTWEIGHT MILITARY APPLICATIONS
In an effort to develop a lightweight, corrosion-resistant, and high-performance alternative to steel for firearm components, this study investigates the optimization of the chemical composition and mechanical properties of aluminium 7075 alloy for potential use in general-purpose machine gun (GPMG) firing pins. The work aimed to identify a tailored aluminium alloy with superior strength-to-weight characteristics by systematically varying the proportions of key alloying elements, zinc (5.1�6.1 wt.%), magnesium (2.1�2.9 wt.%), copper (1.2�2.0 wt.%), and chromium (0.18�0.28 wt.%), in accordance with an L8 orthogonal array design. A total of eight experimental alloy variants were fabricated using a modified stir casting technique, followed by heat treatment and mechanical characterization. Mechanical performance was assessed through hardness, tensile strength, impact toughness, and wear resistance tests, complemented by optical and scanning electron microscopy (SEM) for microstructural evaluation. Results revealed that alloy variant Al7, with 6.1% Zn, 2.9% Mg, 1.2% Cu, and 0.18% Cr, demonstrated superior mechanical performance with a tensile strength of 193.7 MPa, hardness of 110.5 BHN, and acceptable impact toughness of 1.03 J. Microstructural analysis confirmed refined grain boundaries and reduced porosity, contributing to enhanced mechanical integrity. The findings establish Al7 as a viable base material for advanced composite reinforcement and firing pin fabrication, offering potential reductions in component weight and maintenance frequency. This study provides a foundational framework for transitioning from traditional steel to optimized aluminium alloys in military-grade components, advancing local material development in defense manufacturing.
Authors : Lawal, M.Y., Garba, D.K., Imam, A.S. and Guma, T.N.
Category : Open Access Volume (Issue) : 11(2) Date Uploaded : 11th August 2025