Ballistic impact resistance of additive manufactured high-strength maraging steel: An experimental study

Miguel Costas,Christian O Paulsen,Martin Kristoffersen,Vegard Brøtan,Tore Børvik,Filipe Teixeira-Dias,Maisie Edwards-Mowforth

doi:10.1177/20414196211035486

Miguel Costas, Christian O Paulsen + Show 5 more

Open Access

https://doi.org/10.1177/20414196211035486

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Abstract

Maraging steel is a low carbon steel known for its ultra high-strength after heat treatment. In combination with Additive Manufacturing (AM), the properties of maraging steel indicate potential to enable complex geometries and improved performance-to-weight ratios for ballistic protection. This study investigates the ballistic performance of AM maraging steel monolithic plates and profile panels fabricated by powder bed fusion. The mechanical properties of the maraging steel, both in the as-built state and after heat treatment, were revealed through quasi-static and dynamic tests in three different directions with respect to the build direction. Metallurgical studies were also conducted to investigate the microstructure of the material both before and after testing. The ballistic perforation resistance of the maraging steel samples was disclosed in a ballistic range by firing 7.62 mm APM2 bullets towards the different target configurations. Ballistic limit curves and velocities were obtained, demonstrating that the thickest heat-treated AM maraging steel plate has a particularly good potential for ballistic protection. The hard core of the armour piercing bullet broke in all tests and occasionally shattered during tests with heat-treated targets. However, due to the severe brittleness of the material, the targets showed significant fragmentation in some cases and most significantly for the profile panels.

Highlights

Research has shown that the ballistic perforation resistance of steel plates is an almost linear increasing function of the material’s yield strength (Børvik et al, 2009)
In recent years Additive Manufacturing (AM), a fabrication process based on the successive addition of material layer by layer, has introduced capacity for weight-saving intricate geometries to advanced materials
It is worth noting that the yield stress of the bullet core was estimated to be 1200 MPa (Børvik et al, 2009), which is between the yield stress of the as-built and heat-treated material (Figure 6(a))

Summary

Introduction

Research has shown that the ballistic perforation resistance of steel plates is an almost linear increasing function of the material’s yield strength (Børvik et al, 2009). High-strength materials with optimal ballistic capacity can lead to improvements in the performance-to-weight ratio of monolithic armour plates (Demir et al, 2008; Kasilingam et al, 2019; Madhu and Bhat, 2011; Ranaweera et al, 2020). The light-weighting of armour systems has relied on areal density reduction, which after a certain level must be reinforced with advanced materials to achieve the necessary ballistic capacity. Materials with high strength have, typically less flexible manufacturing methods, limiting the opportunity for complex geometry and areal density reduction (Børvik et al, 2005). In recent years Additive Manufacturing (AM), a fabrication process based on the successive addition of material layer by layer, has introduced capacity for weight-saving intricate geometries to advanced materials. A recent study by Kristoffersen et al (2020) demonstrated marginal discrepancy in ballistic response between AM and traditionally die-cast aluminium plates

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