【摘要】 为研究光丝同轴激光增材技术在制备高氮不锈钢块体材料中的应用潜力，采用直径1.2 mm、氮含量为0.71 wt.%的高氮钢丝材，通过光丝同轴激光增材技术进行多道多层增材试验。利用工业CT扫描、氮含量分析、组织形貌观察、物相分析及力学性能测试等方法，对增材块体的内部质量、氮含量、微观组织及力学性能进行了系统研究。结果表明，增材块体中存在少量未熔合缺陷，主要分布在底部，且一般出现于每一层的前两道附近，等效直径主要分布于200～300μm。内部存在大量细小孔洞状低密度缺陷，其体积占比为0.073%，其中约90%的等效直径区间为1.5～7.5μm。中部和顶部的氮含量都在0.66 wt.%以上，氮损失均低于7.5%；底部氮含量降至0.58 wt.%，氮损失为19%。物相分析表明，增材块体主要为奥氏体γ-Fe相，通过SEM和EDS可发现基体材料中存在少量α-Fe枝晶和Mn的氧化物。金相观察发现，增材块体主要由细小的柱状晶和等轴晶组成。增材块体底部力学性能较好，中部各向异性较小。其增材方向上的硬度分布为315～355 HV，且底部明显高于中部和顶部。块体中部增材方向抗拉强度875 MPa，屈服强度为679 MPa，延伸率为50%；行进方向抗拉强度为908 MPa，屈服强度为685 MPa，延伸率为34%。此外，块体底部行进方向的抗拉强度为997 MPa，屈服强度为770 MPa，延伸率为43%。本研究证实了光丝同轴激光增材技术制备高氮不锈钢块体材料的可行性，为高氮不锈钢增材制造技术的开发和应用提供了重要的理论依据和技术支持。更多还原

【Abstract】 In order to explore the potential application of laser additive technology with coaxial wire feeding in the fabrication of high nitrogen stainless steel block materials, experiments were conducted using a high nitrogen steel wire with a diameter of 1.2 mm and a nitrogen content of 0.71 wt.% through the multi-channel and multi-layer additive experiments manufactured by laser additive technology with coaxial wire feeding. Systematic studies were carried out on the internal quality,nitrogen content, microstructure, and mechanical properties of the additive block by means of industrial CT scanning, nitrogen content analysis, microstructure observation, phase analysis, and mechanical property testing. The results indicated that there were a few unfused defects in the additive block, mainly located at the bottom and usually found near the first two passes of each layer, with an equivalent diameter mostly distributed between 200～300 μm. There were numerous fine porous and low-density defects inside, with the volume proportion of 0.073%, among which about 90% had an equivalent diameter between 1.5～7.5 μm. The nitrogen content in the middle and top parts remained above 0.66 wt.%, with nitrogen losses within 7.5%; the nitrogen content at the bottom decreased to 0.58 wt.%, with a nitrogen loss close to 19%. Phase analysis showed that the additive block was primarily composed of austenitic γ-Fe phase. A small amount of α-Fe dendrites and Mn oxides were found in the matrix materials by SEM and EDS. Metallographic observations revealed that the additive block consisted mainly of fine columnar grains and equiaxed grains. The mechanical properties of the base of the additive block were better and the anisotropy in the middle was small. The hardness distribution in the additive direction was within 315～355 HV, which was significantly higher in the bottom than that in the middle and top. This study confirmed the feasibility of high nitrogen stainless steel block material manufactured by laser additive technology with coaxial wire feeding, and provided important theoretical basis and technical support for the development and application of high nitrogen stainless steel additive manufacturing technology.更多还原