On the ballistic perforation resistance of additively manufactured and wrought maraging steel: Experiments and numerical models

The introduction of additive manufacturing (AM) to the defence industry has created possibilities for customisable and optimised light-weight armour. Maraging steel is a low carbon, high-strength steel, well suited to AM fabrication by laser powder-bed fusion (LPBF), that takes on ultra high-strength post heat-treatment, lending it significant potential for protective applications. Promising ballistic performance has been demonstrated in the literature albeit with a tendency for brittle behaviour; it remains unknown to what extent the AM processing is responsible for the unfavourable reduction in ductility. A comparison of AM maraging steel targets alongside traditionally wrought targets under ballistic impact forms the main objective of this study. AM maraging steel in both the as-printed and heat-treated state has been experimentally characterised, examined, and tested in a ballistic range alongside its traditionally wrought counterpart. Very little difference was found in the ballistic limit velocity of the AM maraging steel compared to wrought both before and after heat treatment, despite significant differences in ductility found in tensile tests. In the majority of the ballistic impact tests, damage inflicted on the projectile core was more extensive for the AM targets than for the wrought. Numerical models were constructed in the IMPETUS Solver to simulate the ballistic impact response of the non-heat-treated material. Standard and commonly used material models were implemented, with only simple adjustments to account for the AM material characteristics. The experimentally and numerically determined ballistic limit velocity agreed to within 10%, and numerical results were found to be conservative.