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用改进的径迹显微照相技术研究了50B钢800—1150℃顶端淬火试样中硼分布状态的变化规律及其与硼钢淬透性的关系。试验表明,硼钢淬透性的变化与冷却时硼向奥氏体晶界偏聚的发展速度密切相关。由硼的成分剖面图可定量测定出这种偏聚的发展速度。晶界硼偏聚发展过快或过慢均不利于硼提高淬透性的效应。只有当晶界硼偏聚的发展速度与基体成分相变孕育期相配合时,硼才能发挥最大效应。利用这种观点可以说明硼钢淬透性的变化特征,分析影响硼钢淬透性的各种因素。
The change of boron distribution in the top quenched sample of 800-1150 ℃ for 50B steel and its relationship with the hardenability of boron steel were studied by the improved track micrograph technique. The experiment shows that the change of hardenability of boron steel is closely related to the development speed of segregation of boron to austenite grain boundaries during cooling. By the composition of boron profile can be quantitatively determined the development of this segregation. Boron segregation of the grain boundary is too fast or too slow are not conducive to boron to improve the effect of hardenability. Only when the growth rate of segregation of boron in the grain boundary phase transformation with the matrix phase matching, boron can play a maximum effect. The use of this point of view can explain the changing characteristics of boron steel hardenability analysis of various factors affecting the hardenability of boron steel.