Effects of different annealing time on microstructure and mechanical properties of lightweight Al-containing medium-Mn steel

Abstract

The relationship between the microstructure and mechanical properties of lightweight Al-containing medium-Mn steel with different annealing times was investigated. The results show that the microstructures of the tested steels treated by the I-Q&P process with varying times of annealing are all composed of martensite, α-ferrite, δ-ferrite, and retained austenite. With extended annealing times, the tested steel's martensite/ferrite microstructure exhibits a variety of size and morphological changes. Simultaneously, retained austenite nucleates and grows at high-angle grain boundaries in ferrite/martensite, exhibiting multi-sized, multi-morphology, and diffuse distribution. With appropriate short annealing times, we achieved improved overall mechanical properties for lightweight Al-containing medium manganese steels than with long annealing times. It allows the tested steel to reach a tensile strength of 1000 MPa, an elongation of 48%, and the product of strength and elongation of 48 GPa•%. At this point, the tested steel shows the best overall mechanical properties.

Microstructure and Texture of Pure Copper under Large Compression Deformation and Different Annealing Times

“…These methods have the common advantage of being continuously repeatable experiments that can refine grain sizes until ultra-fine grains are produced [19][20][21][22]. In the original organization, there were a large number of small-angle grain boundaries.…”