Evolution of Microstructures of a Low Carbon Bainitic Steel Held at High Service Temperature
来源期刊：Acta Metallurgica Sinica2014年第3期
论文作者：Chao Sun Shanwu Yang Guoliang Liu
文章页码：436 - 443
摘 要：Low carbon bainitic steel derives the high strength mainly from high density of dislocations rather than carbon and alloy element content, so it tends to evolve into equilibrium microstructure with low density of dislocations under thermal disturbance. In the present investigation, granular bainite and lath-like bainitic ferrite were produced respectively in Mo-free low-carbon steels by changing cooling rate. It has been found that granular bainite possesses a lower strength at room temperature than bainitic ferrite, but it exhibits a slower decrease of strength with temperature increasing. Dislocation density in both granular bainite and bainitic ferrite decreases via recovery and recrystallization at high temperature.However, when reheating of bainite is carried out at temperature below 600 °C, a long time will be needed for incubation of recrystallization, during which the hardness of bainite maintains stable. The property makes bainite, especially granular bainite, become a potential microstructure for matrix of high strength fire-resistant steel.
Chao Sun，Shanwu Yang，Guoliang Liu
School of Materials Science and Engineering, University of Science and Technology Beijing
摘 要：Low carbon bainitic steel derives the high strength mainly from high density of dislocations rather than carbon and alloy element content, so it tends to evolve into equilibrium microstructure with low density of dislocations under thermal disturbance. In the present investigation, granular bainite and lath-like bainitic ferrite were produced respectively in Mo-free low-carbon steels by changing cooling rate. It has been found that granular bainite possesses a lower strength at room temperature than bainitic ferrite, but it exhibits a slower decrease of strength with temperature increasing. Dislocation density in both granular bainite and bainitic ferrite decreases via recovery and recrystallization at high temperature.However, when reheating of bainite is carried out at temperature below 600 °C, a long time will be needed for incubation of recrystallization, during which the hardness of bainite maintains stable. The property makes bainite, especially granular bainite, become a potential microstructure for matrix of high strength fire-resistant steel.
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