Cooling Rate Dependence of Boron Distribution in Low Carbon Steel |
| |
Authors: | Dong Jun Mun Eun Joo Shin Kyung Chul Cho Jae Sang Lee and Yang Mo Koo |
| |
Affiliation: | (1) Graduate Institute of Ferrous Technology, Pohang University of Science and Technology, Pohang, 790-784, Republic of Korea;(2) Neutron Science Division, Korea Atomic Energy Research Institute, Daejeon, 305-353, Republic of Korea;(3) Steel Making Research Group, Technical Research Laboratories, POSCO, Gwangyang, 545-090, Republic of Korea; |
| |
Abstract: | The behavior of boron (B) segregation to austenite grain boundaries in low carbon steel was studied using particle tracking
autoradiography (PTA) and secondary ion mass spectroscopy (SIMS). An effective time method was used to compare the cooling
rate (CR) dependence of this segregation during continuous cooling and its time dependence during isothermal holding. Comparison
of these segregation behaviors has confirmed that the CR dependence of B segregation agrees well with its time dependence
and is mainly a result of the phenomenon of nonequilibrium segregation. Based on the CR dependence of B segregation, the continuous
cooling transformation behavior of B-bearing steel as compared with B-free steel was also investigated using dilatometry and
microstructural observations. The addition of a small amount of B to low carbon steel retarded significantly the austenite-to-ferrite
transformation and finally expanded the range of cooling programs that result in the formation of bainitic microstructures.
Analysis of the B distribution has confirmed that this retardation effect of B on ferrite transformation is attributed to
the CR dependence of B segregation to austenite grain boundaries during cooling after austenitization. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|