Investigation of impact resistance in novel TWIP steel / ceramic composite structures

To enhance the anti-impact protective performance of armor systems and address the demands of lightweight armored vehicles and military equipment, a systematic study was conducted on the ballistic resistance of a silicon carbide (SiC) ceramic/novel TWIP (twinning-induced plasticity) steel composite structure. Samples of the SiC ceramic/TWIP steel composite and monolithic TWIP steel were fabricated for comparative analysis. Single-stage light gas gun plate impact experiments were performed at a flyer impact velocity of 500 m/s to obtain free-surface velocity profiles of both materials under high-velocity loading. The spall strength and strain rate sensitivity of the composite and monolithic steel were calculated from these profiles and statistically compared. Scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) were employed to characterize the microstructural evolution and damage mechanisms, including microvoid nucleation, coalescence, and primary crack propagation, in the impacted samples. Numerical simulations were implemented using LS-DYNA, where the TWIP steel was modeled with the Johnson-Cook (J-C) constitutive equation, and a particle-based method was adopted to simulate the brittle ceramic phase. The simulations were extended to investigate spallation behavior at varying impact velocities and to evaluate the influence of different steel properties on composite performance. Experimental results demonstrate that the composite exhibits 22.76% and 7.09% enhancements in spall strength and strain rate sensitivity, respectively, compared to monolithic TWIP steel. Microstructural analysis reveals that both materials undergo ductile fracture characterized by microvoid coalescence; however, the composite shows significantly weaker spall damage, confirming its superior impact resistance. The numerical model achieves excellent agreement with experimental data, validating its predictive accuracy. Stress distribution analysis during the impact process identifies a critical crack-initiation velocity of approximately 225 m/s. Furthermore, the influence of steel properties on the anti-impact performance of the composite structure was analyzed, demonstrating that the novel TWIP steel exhibits superior performance.