HAN Qihang
,
KANG Yonglin
,
ZHAO Xianmeng
,
L Chao
,
GAO Lufeng
钢铁研究学报(英文版)
Two kinds of ultrahigh strength cold rolled dual phase steels have been developed by designing CSiMnCr and CSiMnCrMo alloy systems. Tensile strength and elongation of both steels exceed 1100 MPa and 10%, respectively. The microstructures of both steels consist of massive martensite and ferrite. And the massive martensite of Mofree steel disperses in the ferrite with volume fraction of 64%. However, the massive martensite of Mocontaining steel is connected or closed by small martensite islands each other, and martensite volume fraction is 69%. As to Mofree steel, the yield strength, yield ratio, and work hardening exponent n are 548 MPa, 049, and 026, respectively. As for Mocontaining one, the yield strength, yield ratio, and n value are 746 MPa, 066, and 033, respectively. Besides, the ferrite of Mofree steel is deformed at the initial stage of plastic deformation. However, for Mocontaining one, Mo solution strengthened ferrite and small overaged martensite islands are deformed preferentially at small strain, which causes the yield strength to reach approximately 200 MPa higher than that of Mofree steel.
关键词:
Mo
,
dual phase steel
,
microstructure
,
property
,
deformation mechanism
YU Hao
,
KANG Yonglin
,
ZHAO Zhengzhi
,
SUN Hao
钢铁研究学报(英文版)
The morphology of manganese sulfide formed during thin slab continuous casting process in lowcarbon steel produced by compact strip production (CSP) technique was investigated. Using transmission electron microscopy analysis, it was seen that a majority of manganese sulfides precipitated at austenite grain boundaries, the morphologies of which were spherical or close to the spherical shape and the size of MnS precipitates ranged from 30 nm to 100 nm. A mathematical model of the manganese sulfide precipitation in this process was developed based on classical nucleation theory. Under the given conditions, the starting and finishing precipitation temperatures of MnS in the continuous casting thin slab of the studied lowcarbon steel are 1 189 ℃ and 1 171 ℃, respectively, and the average diameter of MnS precipitates is about 48 nm within this precipitation temperature range. The influences of chemical components and thermomechanical processing conditions on the precipitation behavior of MnS in the same process were also discussed.
关键词:
morphology;thin slab continuous casting;precipitation kinetics;compact strip production;TEM
