Abstract: The effects of heating rate and annealing temperature on the microstructure and mechanical properties of interstifial-free steel were studied, and the synergistic mechanism of heat treatment parameters on the mechanical properties was revealed. The results showed that with the decrease of heating rate and the increase of annealing temperature, the aspect ratio of the grains decreases and the grains tend to be equiaxed. At a low heating rate, the annealing temperature has a greater effect on the grains. At the same time, the intensity of α-fiber texture decreases with the increase of annealing temperature, while gradually shifts to γ-fiber texture, indicating the formation of recrystallization texture. Tensile tests at room temperature showed that the fracture surfaces are honeycomb-like and belong to typical plastic fractures. With the increase of temperature, the elongation increases, the uniform deformation ability of the material increases, and the drawing ability increases. When the heating rate and annealing temperature are 0.8 ℃/min and 800 ℃, respectively, the minimum aspect ratio is 1.58, the maximum elongation is 40%.

Key words: Interstitial-free steel, heating rate, annealing temperature, microstructure, mechanical properties