Ductile Fracture in WAAM-Fabricated High Strength Steel for Structural Applications

This study investigates the ductile fracture behaviour of coupon-like specimens produced by Wire Arc Additive Manufacturing (WAAM) using AM70 high-strength low-alloy steel wire. Experimental testing under uniaxial tension and shear loading was conducted, supported by digital image correlation to capture strain fields. The material's plastic response was calibrated using a combination of true stress-strain conversion, a weighted average model for post-necking behaviour, and finite element simulations. Ductile damage was implemented numerically to simulate fracture, showing good agreement with experimental results in both failure mode and stress-strain response. The AM70 WAAM material exhibited a fracture strain of 0.65 in uniaxial tension and 0.70 in shear, indicating enhanced ductility compared to high-strength steels and previously reported WAAM references. Despite a moderate reduction in yield strength the material showed promising mechanical performance, particularly under shear-dominated conditions. These findings suggest the suitability of AM70 WAAM components for applications requiring high deformation capacity. The validated modelling approach offers a robust basis for predicting failure, and future work will explore the application of advanced fracture models for improved accuracy across diverse loading conditions.