Abstract: The as-cast Fe-25Mn-3Si-3Al TWIP steel produced by electroslag remelting has cracked in the process of forging at high temperature. The high temperature mechanical properties of Fe-25Mn-3Si-3Al TWIP steel have been investigated using the Gleeble 3500 machine. The results show that the brittleness temperature interval Ⅰ is from 1 250 ℃ to the melting point and the brittleness temperature interval Ⅲ is from 650 ℃ to 800 ℃. By means of the scanning electron microscope, the types of fractures under different tensile temperatures have been analyzed, and the structure morphologies have been observed by optical microscope. The microsegregation of specimens was investigated using electron probe micro analyser, and the phase composition was examined using electron backscatter diffraction detector to determine the fracture mechanisms. The results show that the ferrite eduction and microsgregation make the specimens brittle fracture in brittleness temperature interval Ⅲ. The determining fator is dynamic recrystallization to improve the high temperature plasticity of TWIP steel. The processes of electroslag remelting and hot working should be optimized to avoid cracks in the future.

Key words: TWIP steel, brittleness temperature interval Ⅲ, microsgregation, ferrite, dynamic recrystallization