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Effects of cooling rate on the precipitation behavior of grain boundary carbide and corrosion resistance of 5Cr15MoV stainless steel
Author(s) -
Yan Han,
He Zhijun,
Lü Nan,
Wei Chongyi,
Xu Taixu,
Liu Jihui
Publication year - 2020
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.202011505
Subject(s) - intergranular corrosion , materials science , metallurgy , grain boundary , carbide , corrosion , chromium , chromium carbide , alloy , precipitation , pitting corrosion , carbon steel , microstructure , physics , meteorology
High‐carbon and high‐chromium alloy steels are prone to pitting and intergranular corrosion, which reduces corrosion resistance. The precipitation behavior of the carbides of high‐carbon and high‐chromium alloy steels is one of the main factors affecting pitting and intergranular corrosion of stainless steel. In this study, 5Cr15MoV stainless steel was heated to 1,200℃ and then cooled by cooling rates varying from 25 to 150°C/min. The precipitation behavior of grain boundary carbides of 5Cr15MoV steel at different cooling rates, and its effect on the corrosion resistance of materials was studied. The results show that the carbides of 5Cr15MoV steel mainly precipitate along the grain boundaries, which leads to the formation of chromium‐depleted zones near the grain boundaries and reduces resistance to intergranular corrosion. It has been found that a higher cooling rate shortens the width of the Cr‐depleted zone near the boundary from 0.871 to 0.569 μm, reduces the Cr‐concentration gradient near the grain boundary from 36.422% to 12.667%, and suppresses the nucleus growth rate of grain boundary carbides. As the cooling rate increases, the corrosion current density decreases from 13.29 to 2.42 μA/cm 2 . The corrosion rate is the lowest, while the cooling rate is 150°C/min. The corrosion rate decreases from 218.339 to 158.488 mm/a. The phenomenon of intergranular corrosion and pitting corrosion was found to be weakened; and thereby, it is shown that an intensive cooling rate can improve the corrosion resistance of 5Cr15MoV steel.