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为了开发新一代冷轧低合金超高强钢,利用连续退火实验机对Ti-0.12%、Nb-0.076%的冷轧低合金超高强钢进行连续退火实验,设计了760~830℃四种不同退火温度,研究了退火温度对实验钢的相组成、晶粒尺寸和力学性能的影响.在800℃退火、400℃过时效的条件下,可得到铁素体和少量贝氏体的组织,铁素体晶粒尺寸约为1.4μm,屈服强度可达700MPa.同时利用扫描电镜和透射电镜观察到钢中存在大量纳米尺寸的亚晶结构、少量位错以及纳米级的Ti、Nb的析出物,这些微结构单元对强度有较大的提升作用.
In order to develop a new generation of cold-rolled low-alloy ultra-high strength cold-rolled steel, the continuous annealing experiments of Ti-0.12%, Nb-0.076% cold- Temperature, the influence of annealing temperature on the phase composition, grain size and mechanical properties of the experimental steel was studied.The microstructure of ferrite and a small amount of bainite can be obtained by annealing at 800 ℃ and aging at 400 ℃, The bulk grain size is about 1.4μm and the yield strength is up to 700MPa. Meanwhile, a large number of nano-scale subgrain structures, a few dislocations and precipitates of nano-sized Ti and Nb are observed in the steel by scanning electron microscopy and transmission electron microscopy. Microstructure unit has a greater role in enhancing the strength.