冷却速度对淬火过程中H13钢中碳化物力学性能和析出行为的影响,Materials Research Express

研究了淬火过程中冷却速率（CR）对H13钢中碳化物的力学性能和析出行为的影响。根据XRD分析和EBSD结果，随着CR的增加，残余奥氏体趋于变得更加不稳定，而马氏体逐渐增加。在较高的CR下，硬度值分别增加，而伸长率和冲击能则降低。拉伸强度保持在2.0 GPa以上。三个样品的加工硬化率显着提高，表明在拉伸试验过程中可能会发生相变诱导的塑性效应。此外，当CR超过15 K s -1时，观察到屈服强度增加。可能是由于马氏体的体积分数高，平均晶粒尺寸下降以及细碳化物的析出。通过电解和XRD分析鉴定获得的沉淀物的类型。结果表明主要存在MC，M 6 C和M 7 C 3，这通过SEM-EDS分析和FactSage热力学计算得到了证实。碳化物的尺寸，体积和分布也在SEM下检查。发现沉淀物的体积分数和尺寸均随着CR的增加而减小。根据这些实验数据，可以确定淬火过程的最佳CR，以实现所需的碳化物分布，进而提高机械性能。

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The effects of cooling rate (CR) on the mechanical properties and precipitation behavior of carbides in H13 steel during quenching process were investigated. The retained austenite tends to be more unstable with increasing CRs, while the martensite increases gradually, based on XRD analyses and EBSD results. The values of hardness are increased, and the elongation along with impact energy is decreased, respectively, at higher CRs. Tensile strength remains above 2.0 GPa. Work hardening rates increase considerably in three samples, suggesting that transformation-induced plasticity effect may take place during the tensile test. Moreover, an increase in yield strength is observed when CR exceeds 15 K s−1, possibly due to a high volume fraction of martensite, decline in average grain size and precipitation of fine carbides. Types of the precipitates acquired were identified by electrolysis and XRD analyses. The results indicate the predominant existence of MC, M6C and M7C3, which are confirmed by SEM-EDS analyses and FactSage thermodynamic calculations. The size, volume and distribution of the carbides were also scrutinized under SEM. It is found that the volume fraction and size of the precipitates both decrease with increasing CRs. Based on these experimental data, an optimum CR for the quenching process could be determined to achieve the desired distribution of carbides, which in turn leads to the enhanced mechanical behaviors.