An investigation on damage tolerant design parameter of additively manufactured Al 2024: Fatigue crack growth rate and fracture toughness

Abstract

Additive manufacturing has emerged as a key forefront of the fourth industrial revolution due to its exceptional design freedom and ability to produce lightweight components for different structural applications. However, the unique thermomechanical characteristics of these additive processes introduce several challenges to the structural integrity and the corresponding life of these components. The structural components, specifically in the aerospace industry, are usually designed according to the damage tolerance approach. The Al 2024 alloy is one of the most widely used alloy in structural applications in the aerospace industry due to its high strength-to-weight ratio and excellent fatigue properties. However, studies on the FCGR behaviour of additively manufactured Al 2024 are scarce in the literature; hence, the current study investigates the FCGR behaviour under stress-controlled loading using a stress ratio of 0.2 and 0.3. The aged specimen showed superior mechanical properties compared to the as-printed specimen, and the properties of the T6 aged specimen are comparable to their wrought counterparts. The different precipitate–dislocation interaction is investigated and correlated with corresponding mechanical behaviour. The primary strengthening mechanism in Al 2024 alloy was observed to be the Orowan bypass mechanism in θ(Al2Cu), and S(Al2CuMg) precipitate.