选区激光熔化24CrNiMoY合金钢组织演化与力学性能

目的 为了获取具有高抗拉强度与高伸长率的24CrNiMoY合金钢，用选区激光沉积(SLM)方法进行打印。方法 以24CrNiMoY合金钢粉末为材料，当搭接宽度为0.09 mm、扫描角度为67°、扫描线长度为10 mm、扫描速度为1 000 mm/s时，在能量密度分别为102、116、129、142 J/mm³条件下打印合金钢样品，采用金相、X射线衍射、扫描电镜、透射电镜及拉伸试验等分析手段，对制备样品的微观组织和力学性能进行研究。结果 在所采用的能量密度范围内，SLM制备24CrNiMoY合金钢的显微组织主要是板条马氏体组织，随着能量密度的增加，样品内部的气孔缺陷先减少后增加，硬度和拉伸性能以及冲击韧性呈现先升高后降低的趋势。在能量密度为116 J/mm³时，打印合金钢样品具有最优的综合力学性能，致密度为99.53%，硬度为(388±5.9)HV0.2，抗拉强度为(1 210±11) MPa，屈服强度为(1 124±10) MPa，断后伸长率为(6.2±0.4)%，冲击韧性为80 J/cm²。结论 在SLM打印24CrNIMoY合金钢样品中，较高的致密度及精细的板条马氏体是合金钢样品具有良好力学性能的关键要素，该研究可为SLM打印高抗拉强度与高伸长率的24CrNiMoY合金钢制动盘零件提供重要参考。

Microstructure Evolution and Mechanical Properties of Selective Laser Melting 24CrNiMoY Alloy Steel

The work aims to print through selective laser deposition (SLM) technology to obtain 24CrNiMoY alloy steel with high tensile strength and high elongation. With 24CrNiMoY alloy steel powder as the material, the alloy steel samples with the energy density of 102, 116, 129, 142 J/mm3 were printed by changing the laser power under an overlap width of 0.09 mm, a scanning angle of 67°, a scanning line length of 10 mm, and a scanning speed of 1 000 mm/s. The microstructure and mechanical properties of the alloy steel samples were studied by means of metallography, X-ray diffraction, scanning electron microscope, transmission electron microscope and tensile testing machine. In the range of energy density in the experiment, the microstructure of 24CrNiMoY alloy steel prepared by SLM was mainly lath martensite. With the increase of laser energy density, the porosity defects in the samples first decreased and then increased. The hardness, tensile properties and impact toughness of the sample also showed a trend of first increase and then decrease. It was found that when the energy density was 116 J/mm3, the printed alloy steel sample had the best comprehensive mechanical properties. The density was 99.53%. The hardness was (388±5.9) HV0.2. The tensile strength was (1 210±11) MPa. The yield strength was (1 124±10) MPa. The elongation after fracture was (6.2±0.4)%. And the impact toughness was 80 J/cm2. It can be concluded that the high density and the formation of fine lath martensite in SLM technology are the key factors for preparing 24CrNiMoY alloy steel samples with good mechanical properties. This study can provide an important reference for SLM printed 24CrNiMoY alloy steel brake disc parts with high tensile strength and high elongation.