Study on Dynamic Mechanical Properties and Constitutive Model of Z-Shaped Steel Wire for Sealing Cable

This study investigates the flow stress behavior of Z-shaped steel wire used in cable sealing applications, over a temperature range of 20–500 °C and a strain rate range of 10−4 to 3000 s−1. The primary objective is to establish reliable constitutive data to support accurate numerical simulations in relevant engineering contexts. To this end, quasi-static tensile tests, high-temperature tensile tests, and high-strain-rate dynamic compression tests were conducted using a high–low temperature electronic universal testing machine and a split Hopkinson pressure bar system. The true stress–strain responses were obtained, and the corresponding mechanical properties were systematically analyzed. Experimental results show that at room temperature (20 °C) and within the low strain rate range (10−4–10−1 s−1), the flow stress is insensitive to strain rate variations. However, following yielding, the slope of the flow stress curve increases noticeably with accumulating strain, indicating deformation behavior governed predominantly by strain hardening. Under high-strain-rate conditions at room temperature (20 °C, 102 to 103 s−1), the yield stress increases with increasing strain rate, revealing a pronounced strain rate sensitivity. At elevated temperatures combined with a low strain rate (300–500 °C, 10−3 s−1), both the yield stress and the overall flow stress decrease markedly as the temperature rises, demonstrating significant thermal softening behavior. The microstructure and fracture of Z4 steel wire were observed by SEM to systematically investigate the effects of strain rate and temperature on its microstructural characteristics, thereby revealing the micro-mechanism of the material’s flow stress. Based on these experimental observations, a Johnson–Cook constitutive model was developed for the Z-shaped steel wire used in cable sealing applications. Validation results confirm that the model accurately captures the flow stress evolution of the material under coupled temperature and strain rate conditions.