15-5PH, a martensitic, precipitation hardening stainless steel, can easily form a martensite structure during rapid solidification, especially in the selective laser melting (SLM) process. In our study, the 15-5PH/Gr composites with different mass ratios (0 wt%, 0.1 wt%, 0.2 wt%, 0.5 wt%) of graphene nanoplates (GNPs) were successfully prepared using SLM technology. Through the observation of optical microscopy images and Raman spectra, it is discovered that the GNPs are uniformly dispersed in the 15-5PH/Gr composites. Based on this phenomenon, a flow model is established to explain the process of the secondary dispersion of the GNPs in the molten pool at high temperatures, and then we come up with a mechanism for it. Besides, it is found that GNPs have a strong inhabiting effect on phase transformation of 15-5PH/Gr composites during the rapid solidification of the SLM process, and the inhibition will be enhanced as the GNPs content increases. The mechanical properties of metal matrix composites (MMCs) are significantly influenced by the changes in phase and additive content. According to the mechanical property tests on the 15-5PH/Gr composites, it is found that their ductility and impact toughness have maximum values of 41.1 ± 1.3% and 194.9 ± 3.1 J/cm² respectively, and the friction coefficient of the 15-5PH/Gr composites have a minimum value of 0.34. Compared with the SLM-ed 15-5PH, the improvement of mechanical properties of the 15-5PH/Gr composites on ductility, impact toughness and wear resistance are increased by 130.9%, 97.3% and 45.2% respectively.

15-5PH是一种马氏体、沉淀硬化不锈钢，在快速凝固过程中很容易形成马氏体组织，特别是在选择性激光熔化（SLM）工艺中。在我们的研究中，使用 SLM 技术成功制备了具有不同质量比（0 wt%、0.1 wt%、0.2 wt%、0.5 wt%）的石墨烯纳米片（GNP）的 15-5PH/Gr 复合材料。通过光学显微镜图像和拉曼光谱观察，发现GNPs均匀分散在15-5PH/Gr复合材料中。基于这种现象，建立了流动模型来解释高温下GNPs在熔池中的二次分散过程，并提出了其机理。除了，发现GNPs在SLM快速凝固过程中对15-5PH/Gr复合材料的相变有很强的抑制作用，并且随着GNPs含量的增加，抑制作用会增强。金属基复合材料 (MMC) 的机械性能受相和添加剂含量变化的显着影响。根据对15-5PH/Gr复合材料的力学性能测试发现，其延展性和冲击韧性的最大值分别为41.1±1.3%和194.9±3.1J/cm²分别和15-5PH /石墨复合材料的摩擦系数有0.34的最小值。与SLM-ed 15-5PH相比，15-5PH/Gr复合材料的力学性能在延展性、冲击韧性和耐磨性方面分别提高了130.9%、97.3%和45.2%。