The results show that higher Nb content is favorable for obtaining acicular ferrite (AF).Accelerated cooling promotes AF transformation, and refines lath size of AF.

• 结果表明，铌含量高有利于在极低的冷却速率下获得针状铁素体组织，提高冷却速率则能进一步促进针状铁素体转变，并使铁素体板条得到细化。