Designing Guidelines for Steel Selection and Manufacturing of a Main Battle Tank Torsion Bar

บทคัดย่อ

This work aimed to develop a practical route using alternative material for manufacturing a torsion bar of main battle tank for enabling local production. Firstly, chemical composition and hardness measurements of an original component were performed to establish a substitution baseline and its service performance requirements. From the results, AISI 4340 steel was chosen, since it is equivalent grade and commercially available, offering appropriate hardenability and high strength potential. A heat treatment window of quenching and tempering (QT) process was designed to achieve the required strength–toughness balance under torsional loading service while remaining compatible with local facilities. Hardnesses, tensile properties and torsional responses of QT treated 4340 steel samples were investigated. The obtained mechanical characteristics were benchmarked against the original bar’s performances and applied to identify acceptance targets and process controlling parameters of a proper production, including austenitizing temperature, quenching medium, tempering range, and inspection keys. It was demonstrated that the processed 4340 steel could satisfy the mechanical demands in service of the original bar. This study then provided a feasible design guideline, considering material selection, QT process parameters, and verification which might promote local manufacture to produce such torsion bars, reduce dependency on foreign supplier, and establish a pathway for qualifying future products.