Abstract High chromium white cast iron (HCWCI) is considered a hard machinable material because of its high carbide content, which when associated with a matrix, forms a rigid and very hard microstructure. This work evaluates the effect of the addition of 0.5% niobium (Nb) on the machinability of a HCWCI alloy with 25.6% chromium and 3.2% carbon. The alloys were cast, heat-treated and characterised. The characterisation was performed by X-ray diffractometry, scanning electron microscopy, hardness and carbide volumetric fraction (CVF). The machinability was analysed in materials with and without the addition of Nb during the turning process using polycrystalline cubic boron nitride cutting tools, while varying the cutting speed in dry cutting and lubri-cooling conditions. The output parameters analysed were the tool lifetime, roughness and wear mechanisms. The Nb addition promoted a decrease of CVF and hardness, also resulted in the microstructure refinement, contributing positively to the machinability of HCWCI under both cooling conditions. In general, the use of cutting fluid resulted in lower roughness values and improved life performance of cutting tools, influencing the reduction of the abrasion wear mechanism.

中文翻译：

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添加和不添加铌的高铬淬火白口铸铁的特性和可加工性

摘要 高铬白口铸铁 (HCWCI) 被认为是一种硬质可加工材料，因为其碳化物含量高，当与基体结合时，会形成坚硬且非常坚硬的微观结构。这项工作评估了添加 0.5% 铌 (Nb) 对含 25.6% 铬和 3.2% 碳的 HCWCI 合金的机械加工性的影响。对合金进行铸造、热处理和表征。通过 X 射线衍射、扫描电子显微镜、硬度和碳化物体积分数 (CVF) 进行表征。使用多晶立方氮化硼切削工具在车削过程中添加和不添加 Nb 的材料的可加工性进行了分析，同时在干切削和润滑冷却条件下改变切削速度。分析的输出参数是刀具寿命、粗糙度和磨损机制。Nb 的添加促进了 CVF 和硬度的降低，也导致了微观结构的细化，在两种冷却条件下都对 HCWCI 的可加工性做出了积极贡献。总的来说，切削液的使用降低了刀具的粗糙度值，提高了刀具的寿命性能，影响了磨损机制的减少。