基于SLM工艺制备的C250马氏体时效钢的工艺优化及其组织

采用SLM工艺制备C250马氏体时效钢,并通过金相显微镜(OM)、X射线衍射(XRD)、扫描电镜(SEM)、能谱仪(EDS)、电子背散射衍射(EBSD)、透射电镜(TEM)、密度测量仪等,探究SLM工艺参数对C250马氏体时效钢致密度与组织的影响,并对优化SLM工艺制备所得C250马氏体时效钢的形貌与显微组织进行分析。结果表明,当能量密度处于85～120 J/mm³时,试验钢致密度高于99.5%,组织致密无明显缺陷。当激光功率270 W、扫描速率700 mm/s、扫描间距0.11 mm、铺粉层厚0.03 mm时,致密度可达100%。最优SLM工艺下C250钢的主要相成分为马氏体,可达到97.13%,其内部晶粒极其细小,约为2.7μm,基体内部存在强化相和位错,对C250钢起强化作用。

Process optimization and microstructure of C250 maraging steel prepared by SLM process

C250 maraging steel was prepared by SLM process. Effect of SLM process parameters on relative density and microstructure of the C250 maraging steel by means of metallographic microscopes (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), electron backscattered diffraction (EBSD), transmission electron microscopy (TEM) and density measurement devices. Morphology and microstructure of the C250 maraging steel prepared by optimizing SLM process were analyzed. The results show that when the energy density is 85-120 J/mm³, relative density is higher than 99.5%, and the microstructure is dense without obvious defects. When the laser power is 270 W, the scanning rate is 700 mm/s, the scanning spacing is 0.11 mm, and the powder layer thickness is 0.03 mm, the density of the C250 maraging steel reaches 100%. Under the optimal SLM process, main phase composition of the C250 steel is martensite, which reaches 97.13%, and its internal grains are extremely fine, about 2.7 μm. In the martensite matrix there are also strengthening phases and dislocations to strengthen the C250 steel.