Effects of Coiling Temperature on Microstructures and Mechanical Properties of Micro-alloyed Rephosphorized Steel Sheet

Effects of coiling temperature(600、650 and 700 ℃,respectively) on the microstructures and mechanical properties of micro-alloyed rephosphorized steel sheet were investigated by analyzing its microstructures and mechanical properties in as hot-rolled and as annealed conditions as well as its recrystallization dynamic behaviors during annealing.The results showed that the microstructure and properties of the experimental steel sheet were obviously affected by the hot-rolling coiling temperature and its recrystallization was prohibited significantly,resulting in higher activation energy for recrystallization,when the coiling temperature was decreased from 700 ℃ to 600 ℃.It was also found that the grain sizes at as hot-rolled or as annealed conditions were both little affected by the coiling temperature whereas not only the as hot-rolled strength and as annealed strength were increased as the coiling temperature decreased,but also the mechanical properties at as annealed conditions became more sensitive to annealing temperature.