In high carbon steel, TTT nose temperature rises and upper baninte becomes easy to be formed with quantity of Si addition. Generation of upper bainite is reduced by boron addition. In this study, the influence of boron addition on isothermal transformation behavior in Si-added high carbon steel was clarified. By boron addition, lamellar spacing and growth rate of pearlite doesn’t change, but the nucleation of pealite is reduced. But nucleation of pearlite is promoted when Fe₂₃(C,B)₆ precipitates. In the Si-added high carbon steel, upper bainite is often formed with the generated ferrite on prior austenite grain boundary. It is inferred that boron reduces ferrite generation in grain boundary which causes upper bainite formation. It is confirmed that effective existence state of boron is grain boundary segregation.

在高碳钢中，随着添加Si量的增加，TTT的鼻端温度升高，并且易于形成上巴氏合金。硼的添加减少了上贝氏体的产生。在这项研究中，阐明了硼添加对添加硅的高碳钢中等温转变行为的影响。通过添加硼，珠光体的层状间距和生长速率不变，但减少了珍珠岩的成核。但是，当Fe ₂₃（C，B）₆时，珠光体的形核得到促进沉淀。在添加了Si的高碳钢中，上贝氏体通常在原奥氏体晶界上形成有生成的铁素体。可以推断出，硼减少了晶界中铁素体的生成，这导致了上贝氏体的形成。可以确认硼的有效存在状态是晶界偏析。