【摘要】 选区激光熔化（SLM）技术是目前WC-Co硬质合金增材制造的主要工艺之一，但由于金属相和陶瓷相在物理性质上存在显著差异，如何基于SLM工艺打印得到无裂纹和孔洞、且具有高性能的硬质合金零件仍然面临重要挑战。本文首先基于熔点差异相对较小的WC-Ti粉，研究了激光功率、扫描速率、扫描间距对成形试样孔隙率的影响规律，由此建立了激光工艺参数与打印件致密性的函数关系，发现扫描速率对成形试样致密性的影响最为显著。在此基础上，通过进一步协同优化激光光斑尺寸和粉末粒径，SLM打印WC-Co硬质合金的孔隙率降低至1.5%，完全消除了裂纹，并结合分子动力学模拟揭示了激光光斑尺寸和粉末粒径的优化匹配对抑制打印硬质合金中形成裂纹、孔洞等缺陷的作用机理。基于优化的WC-Co复合粉末、SLM成形和后续热处理条件，打印获得了具有双晶组织特征、近全致密的硬质合金切削刀片，维氏硬度为（1 300±20）HV30，抗弯强度为（1 020±130）MPa，压缩强度达到（3 520±240）MPa，综合力学性能与同成分、类似晶粒尺寸的烧结硬质合金相当，显示出良好的应用前景。更多还原

【Abstract】 elective laser melting(SLM) technology is currently one of the primary processes for additivemanufacturing of WC-Co cemented carbides. However, due to the significant differences in physical properties between themetallic and ceramic phases, obtaining crack-free and pore-free cemented carbide components with high performancethrough SLM printing remains a significant challenge. This work first investigated the influence of laser power, scanningspeed, and hatch spacing on the porosity of the fabricated specimens by using WC-Ti powder, which has a relatively smalldifference in melting points. On this basis, a function relationship between laser process parameters and the density of theprinted parts was established. It was found that the scanning speed had the most significant impact on the density of thefabricated specimens. Moreover, by further synergistically optimizing the laser spot size and powder particle size, the porosity of SLM-printed WC-Co cemented carbides was reduced to 1.5%, and cracks were eliminated. Molecular dynamicssimulations were employed to reveal the mechanism by which the optimized matching of laser spot size and powder particlesize inhibited the formation of cracks, pores, and other defects in the printed cemented carbides. Based on optimized WCCo composite powder, SLM technology, and subsequent heat treatment conditions, a nearly fully dense cemented carbidecutting insert with a bimodal grain microstructure was fabricated. The insert exhibited a Vickers hardness of(1 300 ± 20)HV30, a bending strength of(1 020 ± 130) MPa, and a compressive strength of(3 520 ± 240) MPa. The overall mechanicalproperties of this material are comparable to those of sintered cemented carbides with similar compositions and grain sizes,demonstrating promising application prospects.更多还原