The excellent abrasion resistance of high-chromium cast irons (HCCIs) is given by an optimal combination of hard eutectic and secondary carbides (SC) and a supporting matrix. The tailoring of the microstructure is performed by heat treatments (HTs), with the aim to adjust the final properties (such as hardness and abrasion resistance). In this work, the influence of chemical composition on the microstructure and hardness of HCCI_26%Cr is evaluated. An increase in the matrix hardness was detected after HTs resulting from combining precipitation of M₂₃C₆ SC during destabilization, and austenite/martensite transformation during quenching. Kinetic calculations of the destabilization process showed that M₇C₃ secondary carbides are the first to precipitate during heating, reaching a maximum at 850 °C. During subsequent heating up to 980 °C and holding at this temperature, they transformed completely to M₂₃C₆. According to the MatCalc simulations, further precipitation of M₂₃C₆ occurred during cooling, in the temperature range 980–750 °C. Both phenomena were related to experimental observations in samples quenched after 0-, 30-, 60- and 90-min destabilization, where M₂₃C₆ SC were detected together with very fine SC precipitated in areas close to eutectic carbides.

中文翻译：

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热处理和化学成分对高铬铸铁中二次碳化物析出和硬度的影响

高铬铸铁（HCCI）的优异耐磨性是硬质共晶和二次碳化物（SC）与支撑基体的最佳组合。微观结构的调整是通过热处理（HT）进行的，目的是调整最终性能（例如硬度和耐磨性）。在这项工作中，评估了化学成分对HCCI_26％Cr的组织和硬度的影响。在HTs之后，检测到基体硬度增加，这是由于不稳定过程中M ₂₃ C ₆ SC的沉淀与淬火过程中奥氏体/马氏体相结合所致。失稳过程的动力学计算表明，M ₇ C ₃次生碳化物在加热过程中最先析出，在850°C时达到最大值。在随后加热到980°C并保持在此温度下，它们完全转变为M ₂₃ C ₆。根据MatCalc模拟，在980-750°C的温度范围内，冷却期间M ₂₃ C ₆进一步析出。两种现象都与在0、30、60和90分钟去稳定后淬灭的样品中的实验观察有关，其中在靠近共晶碳化物的区域中检测到M ₂₃ C ₆ SC以及非常细的SC沉淀。