Song XIANG
,
Guoquan LIU
,
Yang LI
,
Changrong LI
,
ong WANG
,
null
,
null
,
null
,
null
,
null
材料科学技术（英）
Microalloying element Nb in low carbon steels produced by compact strip production (CSP) process plays an important role in inhibiting recrystallization, decreasing the transformation temperature and grain refinement. With decreasing the rolling temperature, dislocations can be pinned by carbonitrides and the strength is increased. Based on the two sublattice model, with metal atom sublattice and interstitial atom sublattice, a thermodynamic model for carbonitride was established to calculate the equilibrium between matrix and carbonitride. In the steel produced by CSP, the calculation results showed that the starting temperature of precipitation of Ti and Nb are 1340℃ and 1040℃, respectively. In the range of 890-950℃, Nb rapidly precipitated. And the maximum of the atomic fraction of Nb in carbonitride was about 0.68. The morphologies and energy spectrum of the precipitates showed that (NbTi) (CN) precipitated near the dislocations. The experiment results show that Nb rapidly precipitated when the temperature was lower than 970℃, and the atomic fraction of Nb in carbonitride was about 60%-80%. The calculation results are in agreement with the experiment data. Therefore the thermodynamic model can be a useful assistant tool in the research on the precipitates in the low carbon steels produced by CSP.
关键词:
Compact strip production
,
strip
,
production
,
niobium
,
low
,
car
Hao YU
,
Hao REN
,
Yonglin KANG
,
Kelu WANG
材料科学技术（英）
Two experiments were carried out on the same compact strip production (CSP) line, which differs in that one of them experienced γ→α→γ﹡thermal history. The differences in microstructure, precipitation, misorientation etc between two experiments were investigated by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron back-scattered diffraction (EBSD) and positron annihilation technique (PAT). The carbon concentration in matrix is more inhomogeneous in the experiment than that withγ→α→γ﹡ thermal history. The specific precipitation characteristic in the experiment withoutγ→α→γ﹡ thermal history is discussed on the basis of different carbon diffusion behavior and interaction between dislocation and excess carbon.
关键词:
Compact strip production
,
null
,
null
,
null
,
null
