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硼在钢和铸铁中既易偏析,又易形成含B硬相——Fe_2B,Fe_3(C,B)和Fe_(23)(C,B)_6等。在Fe-C-B三元系熔化平衡研究(共6个截面,83个试样)的基础上,选择部分试样进行正常冷却(接近铸造冷却条件)和1050℃加热后(接近平衡条件)的显微组织分析以及X-射线衍射晶体分析,得到化学成分、冷却条件与硬相类型、形成方式、形态之间的关系;在X-射线衍射晶体分析的基础上得出了不同冷却条件下的I/I_0—浓度图,即化学成分与硬相数量之间的关系以及Fe_3(C,B)晶格常数、显微硬度与化学成分的关系。研究结果为简便准确区别不同的含B硬相、合理选择化学成分和热处理工艺提供了重要依据。文中对Fe_(23)(C,B)_6→Fe_3(C,B)+γ-Fe相变对硬相形态的影响等提出了见解。
Boron is easily segregated in both steel and cast iron, and easily forms B hard phases - Fe 2 B, Fe 3 (C, B) and Fe 23 (C, B) 6. On the basis of the Fe-CB ternary system (a total of 6 sections and 83 samples), some samples were selected for normal cooling (near the casting cooling condition) and 1050 ℃ (close to equilibrium conditions) Microstructure analysis and X-ray diffraction crystal analysis, chemical composition, cooling conditions and the type of hard phase, the formation of forms, the relationship between the form; X-ray diffraction analysis based on the crystal obtained under different cooling conditions I / I_0- concentration diagram, that is, the relationship between the chemical composition and the amount of hard phase, as well as the relationship between the lattice constants of Fe_3 (C, B), microhardness and chemical composition. The results provide an important basis for the simple and accurate distinction of different B-containing hard phases, reasonable choice of chemical composition and heat treatment process. In this paper, some opinions are put forward on the influence of the phase transformation of Fe_ (23) (C, B) _6 → Fe_3 (C, B) + γ-Fe on the morphology of hard phases.