Study on High-Temperature Mechanical Properties of Low-Carbon Fe-Mn-Si-Al TWIP Steel

摘要

The high-temperature mechanical properties of twinning-induced plasticity (TWIP) steel with 0.05% C, 25 % Mn, 3 % Al, 3 % Si have been investigated using the GLEEBLE 3500 machine. The result shows that the zero ductility temperature and the zero strength temperature of the TWIP steel are measured at 1,225 ℃ and 1,275 ℃, respectively. The brittleness temperature interval I is from 1,200 ℃ to the melting point, and the brittleness temperature interval Ⅲ is from 650 ℃ to 800 ℃. The tensile fracture has been examined using the scanning electron microscope, optical microscope and electron backscatter diffraction to determine the fracture mechanisms. The result shows that the twin is not the main influencing factor of the high-temperature plasticity of TWIP steel. Instead, the degree of dynamic recrystallization determines its high-temperature plasticity. A small number of AlN particles are found near the fractures, but these particles are so coarse, therefore, have no influence on-the brittle fracture, and ferrite transformation and work hardening are the main reasons that cause the brittle fracture.