【摘要】 以316L不锈钢焊丝作为沉积材料，分别研究了纯N₂和纯Ar保护气氛对热丝激光增材制造（LAM）试样微观组织、力学性能及晶界腐蚀行为的影响规律。结果表明：增材试样组织主要为奥氏体，枝晶间分布少量铁素体，Ar试样的含氮量为0.047%,N₂试样的含氮量为0.052%。N₂试样枝晶间距较少，晶粒取向以<001>为主，Ar试样枝晶较大，晶粒取向以<101>为主。N₂试样的抗拉强度（602.9 MPa）与屈服强度（430.6 MPa）较Ar试样（541.6 MPa、411.0 MPa）分别提升11.3%和4.8%，同时延伸率保持43.6%。N₂试样的腐蚀速率较Ar试样低，氮元素通过减缓贫铬区形成及晶粒细化，协同阻碍腐蚀的扩展。研究结果为N₂保护增材制造奥氏体不锈钢提供了试验依据和理论指导。更多还原

【Abstract】 This study utilized 316L stainless steel welding wire as the deposition material to systematically investigate the effects of nitrogen and argon shielding gas atmospheres on the microstructure, mechanical properties, and intergranular corrosion behavior of hot-wire laser additive manufacturing(LAM) specimens. The results revealed that the additively manufactured samples primarily exhibited an austenitic matrix with minor ferrite distributed along dendrites. The nitrogen content was 0.047 wt.% in argon-protected samples and 0.052 wt.% in nitrogen-protected samples. Nitrogen-protected samples displayed reduced secondary dendrite arm spacing, predominantly featuring a <001> grain orientation, whereas argon-protected samples exhibited larger dendrites and a predominant <101> orientation. Nitrogen-protected samples demonstrated superior mechanical properties, achieving tensile strength(602.9 MPa) and yield strength(430.6 MPa) values 11.3% and 4.8% higher than those of argon-protected samples(541.6 MPa, 411.0 MPa), respectively, while maintaining an elongation of 43.6%. The corrosion rate of nitrogen-protected samples was lower than that of argon-protected samples. Nitrogen was identified as a critical factor in mitigating chromium depletion zone formation and refining grains, synergistically suppressing intergranular corrosion propagation. These findings provide experimental and theoretical guidance for optimizing nitrogen-shielded additive manufacturing of austenitic stainless steels.更多还原