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利用光学显微镜和力学性能测试方法,研究了不同N含量下热轧结构钢组织和力学性能差异;同时采用透射电镜和化学物相分析的方法,观察和分析了析出相粒子的形态和分布情况。结果表明,对结构钢中增N可有效促进纳米碳化物的析出,从而制备出抗拉强度达815 MPa、总伸长率达23%的超高强输电铁塔钢;当N增加至4.2×10-4时并不明显降低冲击韧性,-40℃冲击条件下冲击功为33.3 J/mm2。N含量增加能明显促进V(C,N)的析出和析出物尺寸的细化,同时减小V(C,N)相间析出的排间距,提高1~10 nm粒子的体积分数,从而提供最强的析出沉淀强化作用,提高钢的力学性能。
The microstructure and mechanical properties of hot-rolled structural steel with different N contents were studied by optical microscope and mechanical property test. The morphology and distribution of precipitated phase particles were observed and analyzed by transmission electron microscopy and chemical phase analysis. The results show that the increase of N in the structural steel can effectively promote the precipitation of the nanocrystalline carbides, so as to prepare ultra-high-strength transmission tower steel with a tensile strength of 815 MPa and a total elongation of 23%. When N increases to 4.2 × 10- 4 does not significantly reduce the impact toughness, impact energy at -40 ℃ impact of 33.3 J / mm2. The increase of N content can obviously promote the precipitation of V (C, N) and the refinement of precipitates, and at the same time decrease the row spacing of V (C, N) precipitates and increase the volume fraction of 1 ~ 10 nm particles, Strong precipitation precipitation strengthening effect, improve the mechanical properties of steel.