超细化针状铁素体/贝氏体组织的热稳定性
Thermo-stability of Ultra-fine Acicular Ferrite / Bainite Microstructure
苑少强1, 梁国俐1, 张晓娟1, 刘 义2
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作者单位：1. 唐山学院 科研处, 河北 唐山 063000; 2. 河北钢铁集团有限公司, 河北 石家庄 050000
中文关键字：超细化； 针状铁素体/贝氏体组织； 硬度； 组织演化
英文关键字：ultra-fine; acicular ferrite/bainite; hardness; microstructure evolution
中文摘要：利用硬度测量和金相观察，研究了Mn-Mo-Nb-B超细化针状铁素体/贝氏体组织在500～700 ℃重新加热过程中组织的演化和性能。结果显示：实验轧制的超细化组织在再加热保温过程中硬度变化有起伏，在550和650 ℃保温情况下， 硬度曲线出现双硬化峰现象；而在700 ℃保温时，只出现一个硬化峰。650 ℃保温20 h时发现有再结晶发生，48 h时大部分非平衡组织均转变为多边形铁素体组织；700 ℃保温48 h的各个阶段组织演化速度明显加快，48 h时，几乎完全由平行排列的多边形铁素体构成，原奥氏体晶界依然可见。同以往的研究结果相比，该实验轧制的超细化非平衡组织具有良好的热稳定性。
英文摘要：Using hardness measurement and metallography observation, the evolution of microstructure and property of ultra-fine acicular ferrite/bainite Mn-Mo-Nb-B steel during reheating at 500～700 ℃ were investigated. The experimental results show that the hardness curves of testing steel fluctuate during reheating and isothermal holding. The two hardness peaks appear when holding at 550 ℃ and 650 ℃. While holding at 700 ℃, only single hardness peak is found. The recrystallization occurs at 650 ℃ for 20 h, when the holding time is 48 h, the most of non-equilibrium microstructure transform into polygonal ferrite. However, while holding at 700 ℃ for 48 h, the evolution process is accelerated at each period. Finally, the complete paralleled polygonal ferrite forms as holding for 48 h, but the prior austenite boundaries can be seen to some extent. Compared with the established works, the ultra-fine non-equilibrium microstructure rolled in labs has better thermal stability.