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Microstructure Transformation Behavior of Hot‐Rolled Steel Oxide Scale during the Preheating Process
Author(s) -
Sun Bin,
Cheng Lei,
You Hong-Guang,
Cao Guang-Ming
Publication year - 2021
Publication title -
steel research international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.603
H-Index - 49
eISSN - 1869-344X
pISSN - 1611-3683
DOI - 10.1002/srin.202000422
Subject(s) - wüstite , eutectic system , materials science , oxide , microstructure , metallurgy , layer (electronics) , composite material
The microstructure transformation of oxide scale in hot‐rolled steel strips during the preheating process is studied by thermal simulation at temperatures ranging from 530 to 800 °C. The results show that the original structure of the oxide scale comprises an outer Fe 3 O 4 layer, an inner Fe 3 O 4 /Fe eutectoid, and some precipitated Fe 3 O 4 . The Fe 3 O 4 /Fe eutectoid structure is first transformed into wüstite. After the eutectoid structure is completely transformed into wüstite, Fe 3 O 4 precipitates are transformed into wüstite with aging. Then, white Fe is dissolved and diffused into wüstite to give a homogenous wüstite layer. The thickness of outer Fe 3 O 4 layer decreases as the temperature increases, indicating that the outer Fe 3 O 4 also transforms into wüstite. The heating rate and temperature are important parameters influencing the phase transformation of the oxide scale. More wüstite is formed at a slower heating rate and higher temperature; a larger number of pores are found inside the wüstite layer with increasing temperature; pores caused by transformation of the oxide scale are created by the density difference between wüstite and Fe 3 O 4 .