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采用物理化学相分析、高分辨透射电镜等手段研究V-N微合金化钢在正火过程中第二相行为,并进行相应的理论计算,讨论该行为对材料性能产生的影响.正火加热保温过程中,V-N钢有约32.9%的V(C,N)未溶解,阻止奥氏体晶粒长大.在正火冷却过程中,未溶解的V(C,N)诱导晶内铁素体形核,细化铁素体晶粒,而溶解的V(C,N)重新析出,起到析出强化作用.V(C,N)析出相行为的变化导致材料力学性能的改变.与热轧态V-N钢相比,正火态V-N钢细晶强化贡献值增加31 MPa,而析出强化贡献值减少45 MPa.
The second phase behavior of VN microalloyed steels in normalizing process was studied by means of phase analysis and high-resolution transmission electron microscopy, and the corresponding theoretical calculations were carried out to discuss the effect of this behavior on the material properties. V (C, N) in VN steels is undissolved at about 32.9%, preventing austenite grains from growing in. During normalizing cooling, undissolved V (C, N) induces intragranular ferrite nucleation , The ferrite grains are refined, and the dissolved V (C, N) re-precipitates, which will precipitate and strengthen.The change of V (C, N) precipitation phase behavior leads to the change of the mechanical properties of the material.Compared with hot rolled VN In comparison with steel, the contribution of fine grain strengthening of normalized VN steel increases by 31 MPa, while the contribution of precipitation strengthening decreases by 45 MPa.