Effect of solution treatment on mechanical properties and microstructure of welded joints of Fe-29Mn-9Al-0.9C low-density steel

Abstract

In recent years, Fe–Mn–Al–C steel has been widely regarded as a promising lightweight material due to its excellent specific strength and good balance of strength and toughness. However, the performance of welded joints is crucial for the application of Fe–Mn–Al–C low-density steel. This paper aims to study the effect of different solution treatment times on the mechanical properties and microstructure of tungsten inert gas (TIG) welding of Fe-29Mn-9Al-0.9C low-density steel. After solution treatment, the phase types of the weld change and the granular ferrite transforms into austenite. Electron backscattered diffraction (EBSD) results show that with the increase of solution treatment time, dislocation density decreases, recrystallized grains grow, and the texture changes from uniform distribution to cubic texture again. It is concluded that in the early stage of recrystallization, dislocation walls are formed due to dislocation slip, which impedes dislocation movement in the process of stretching and thus improves the tensile strength. By controlling the time of solution treatment, the maximum tensile strength can be increased to 845.05[Formula: see text]MPa and the maximum elongation can be increased to 38.21%, which are all higher than for the welded joints without solution treatment.