Effect of Coiling Temperature on Microstructure and Properties of a Ti–Nb Microalloyed High‐Speed Guardrail Steel

The effects of coiling temperature on microstructure and properties of a Ti–Nb microalloyed high‐speed guardrail steel are investigated. The results show that when the coiling temperature varied from 570 to 670 °C, the optimum comprehensive mechanical properties are obtained at the coiling temperature of 620 °C. The yield strength, tensile strength, and total elongation are 729, 813 MPa, and 11.8%, respectively. The difference in yield strength between the samples at varying coiling temperature is attributed to different strengthening effects of grain refinement, precipitation, and dislocation strengthening, among them the grain refinement and precipitation strengthening contributions are dominating, with contributions of 290 and 186 MPa, respectively, at 620 °C. Moreover, the fine nano‐scale (Ti, Nb)C particles are formed during and after the coiling stage.