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研究了含氮量和第三代热机械加工工艺(TMCP)参数对低碳微合金V-N钢力学性能和显微组织的影响。对系列超高氮和超低碳含量的微合金V-N钢进行了不同工艺的控制轧制,对轧后试样进行了力学性能测试、显微组织观察以及晶粒大小的测定。结果表明,试验钢中氮含量的增加及终轧温度的降低均可使晶粒细化,强度相应提高,但钢中N含量过高显著损害塑性。试验钢高温变形奥氏体中析出微细VN粒子,该粒子诱导轧后冷却期间γ→α相变初期晶内铁素体的生成,产生细晶强化,是V-N微合金钢的重要强化机制之一。
The effects of nitrogen content and TMCP parameters on the mechanical properties and microstructure of low carbon microalloyed V-N steel were investigated. The series of controlled rolling of the series of ultra-high nitrogen and ultra-low carbon microalloyed V-N steels were carried out. The mechanical properties, microstructure and grain size of rolled samples were measured. The results show that both the increase of nitrogen content and the decrease of the finish rolling temperature can make the grain refine and the strength increase correspondingly. However, the high content of N in the steel significantly deteriorates the ductility. The microstructure of VN particles precipitated in high temperature deformation austenite of the test steel. The grain induces the formation of intragranular ferrite during the initial γ → α phase transformation after rolling, resulting in fine grain strengthening. It is one of the important strengthening mechanisms of VN microalloyed steel .