نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشکده مهندسی مواد، دانشگاه صنعتی سهند
2 گروه فرآیند و فرآوری، دانشکده مهندسی مواد، دانشگاه صنعتی اصفهان
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Martensitic microstructure, due to providing numerous nucleation sites for austenite, is considered as the initial microstructure in the dual-phase steel fabrication process, i.e. intermediate quenching. In the present study, the microstructural evolution of a carbon-manganese steel during intermediate quenching at three temperature ranges (upper-critical (AC₃<T), inter-critical (AC₁<T<AC₃) and sub-critical (T<AC₁)) was studied using optical microscopy, scanning electron microscopy, and X-ray diffraction analysis. According to the corresponding hardness of different microstructures, it was found that the sub-critical annealing process, the high-temperature tempering process, has two stages with different softening rates. The first stage is associated with the removal of carbon from the lattice structure to form carbides, and the second stage is accompanied by the coarsening of carbides. Annealing martensitic microstructure at intercritical temperatures also shows three stages: The first stage is the tempering of martensite, the second stage is the nucleation and growth of austenite in tempered martensite, and the dissolution of carbides, and the third stage is the coarsening of the two-phase microstructure, which is associated with reduction in hardness. An increase in temperature up to upper-critical temperatures also causes the appearance of these three stages, but considering the intensified diffusion at high temperatures, these stages are shortened and merged together.
کلیدواژهها [English]
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