Recovery, Recrystallization, and Mechanical Properties of Low Carbon Steel during Fast Annealing Between 600-700 °C
摘要
The fast annealing was performed on the cold-rolled 16Mn sheet steel with a thickness of 0.5-0.6 mm. The heating and cooling rates of temperature were 50 °C/s, and the samples were kept at 600, 625, 650, 675, 700 °C for 20 s, respectively. The microstructure and mechanical properties were studied by XRD, SEM, EBSD, and tensile tests. The results indicate that the cold-rolled 16Mn steel undergoes recovery between 600 and 650 °C, but there is no significant change in strength and elongation. Strong recovery occurs during annealing at 650 °C, resulting in an increase in small angle grain boundaries and a decrease in dislocation density. When annealed at 675 °C and 700 °C, 56.1% and 70.2% of recrystallized grains appear, respectively. Fast annealing at 700 °C improves strength and hardness while sacrificing part of elongation. The tensile properties are 663 MPa of yield strength, 702 MPa of tensile strength 10.8% of elongation, and 223 HV0.5 of hardness. However, their hot-rolled states are 453 MPa, 602 MPa, 29%, and 207 HV0.5, respectively. When fast annealed at 675 °C and 700 °C, the degree of recrystallization is related to the grain size, and the recrystallization kinetics is mainly controlled by grain growth, rather than recrystallization nucleation.