Microstructure-driven mechanical response and constitutive modeling of a Fe–Cr–C hardfacing deposit under quasi-static and dynamic loading

Fe-Cr-C hardfacing alloys are widely used to protect components in severe and complex environments, yet their intrinsic mechanical response under controlled loading remains insufficiently documented. This work presents a combined experimental–numerical investigation of a highly alloyed Fe–Cr–C hardfacing deposit welded onto an S355MC base substrate, with emphasis on the coupling between microstructural gradients, strain-rate effects, and damage-driven behavior. Compression samples extracted at several distances from the substrate–deposit interface were tested in compression from quasi-static to dynamic regimes using a universal quasi-static press and a Split Hopkinson Pressure Bar (SHPB) apparatus, complemented by high-speed imaging and digital image correlation. The deposit exhibits a high-strength, low-ductility response with compressive strengths up to 2.5 GPa and failure governed by early damage and brittle fragmentation. Strong differences are observed between carbide-rich upper layers and more diluted interfacial regions, highlighting the key role of local microstructure and defect populations. Experimental-mechanical results were numerically modeled using the non-linear explicit code IMPETUS Afea Solver. A Johnson–Holmquist (JH-2) constitutive model was calibrated through an analytical identification, optimization, and inverse numerical simulations. The model successfully reproduced the deposit stress–strain relationship and main fracture features for different microstructural states. The proposed framework provides a practical approach for integrating experimentally derived material laws into more severe loading numerical scenarios (impact, blast, etc.) involving Fe–Cr–C hardfacings.