Describing crack growth in additively manufactured Scalmalloy

Abstract

Whilst aluminum alloys are widely used in military aircraft, space vehicle, and satellites, most of the work on the durability and damage tolerance (DADT) assessment of additively manufactured (AM) parts has focused on other types of materials. AM Scalmalloy®, which has a yield strength greater than 450 MPa and an elongation greater than 10%, appears to have the potential to meet the certification requirements needed for load bearing “aluminum alloy” aerospace parts. However, the ability to characterize crack growth is central to certification. As a result the present paper addresses crack growth in the AM Scalmalloy®. It is shown that when expressed as per the Hartman-Schijve crack growth equation, the curves for AM Scalmalloy® essentially collapse onto a single curve that is associated with the growth of both long and short cracks in the aluminum alloy AA7075-T7351. It is suggested that this finding has the potential to simplify the process for determining the upper bound growth curves required in NASA HDBK-5010 for the certification of AM space parts.

Keywords

• Additive manufacturing
• Fatigue crack growth
• Scalmalloy®
• Hartman-Schijve equation