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采用热模拟方法研究了微量B对低碳钢动态CCT曲线的影响。结果表明,随冷却速度增加,S355-J1钢和含硼S355-J1钢先后发生铁素体(珠光体)相变→贝氏体相变→马氏体相变,并且分别在5℃/s和3℃/s出现贝氏体;相同冷速下,含硼钢的铁素体相变温度更低,而贝氏体相变温度更高。微量硼偏聚在奥氏体晶界,抑制铁素体形核并促进贝氏体形成,提高了低碳钢的淬透性。
The effects of trace amount of B on the dynamic CCT curve of mild steel were studied by thermal simulation. The results show that the ferrite (pearlite) transformation → bainite transformation → martensitic transformation occurs successively in S355-J1 steel and boron-containing S355-J1 steel with the increase of cooling rate, And 3 ℃ / s appear bainite; the same cooling rate, boron-containing steel ferrite transformation temperature is lower, and the bainite transformation temperature is higher. Trace boron segregation in the austenite grain boundaries, inhibit ferrite nucleation and promote bainite formation, improve the hardenability of mild steel.