关键词: 低碳钢, 微观组织, 高温力学性能, EBSD

Abstract: The microstructure and high temperature mechanical properties of a low carbon steel at different temperatures were studied and discussed in detail by means of field emission scanning electron microscopy (FE-SEM), electron backscatter diffraction (EBSD) and electronic universal testing machine. The results show that regardless of room temperature tensile test or high temperature tensile test, carbide(Fe₃C) particles located on grain boundaries are the main factor for inducing cracks for the tested low carbon steel. Compared with the tensile properties at room temperature, increasing the heating temperature, the tensile strength is significantly reduced and the elongation is significantly increased. At high temperatures, with the increase of temperature, the tensile strength decreases linearly, while the elongation decreases first and then stabilizes. A large number of slip bands are observed during the stretching at 520 ℃, which induces dynamic recovery. When the temperature is increased to 720 ℃, the pearlite structure becomes spheroidized, and the equiaxed small grains appear in the deformed ferrite grains, which means that dynamic recrystallization has occurred. According to the EBSD analysis, the misorientation between the deformed ferrite grains is large, and the misorientation between the equiaxed small grains where recrystallization occurs is small.

Key words: low carbon steel, microstructure, high temperature mechanical properties, EBSD