选区激光熔化成形高氮不锈钢组织与力学性能研究  

Microstructure and Mechanical Properties of High-Nitrogen Stainless Steel Manufactured by Selective Laser Melting

作　　者：吕源 李涛[1] 刘捷 王克鸿[1] LüYuan;Li Tao;Liu Jie;Wang Kehong(Key Laboratory of Controlled Arc Intelligent Additive Manufacturing Technology,Ministry of Industry and Information Technology,Nanjing University of Science and Technology,Nanjing 210094,Jiangsu,China)

机构地区：[1]南京理工大学受控电弧智能增材技术工业和信息化部重点实验室,江苏南京210094

出　　处：《中国激光》2022年第22期230-238,共9页Chinese Journal of Lasers

基　　金：江苏省自然科学基金(BK20200502)。

摘　　要：采用选区激光熔化(SLM)技术制备高氮钢构件,研究了激光体积能量密度对氮含量、致密度、物相组成、拉伸性能的影响,探索了高氮钢强韧化机制。研究表明:在体积能量密度从190.5 J·mm^(-3)增大到285.7 J·mm^(-3)的过程中,增材件致密度与拉伸性能呈先升高后降低的变化趋势。当激光扫描功率为200 W、扫描速度为400 mm/s、体积能量密度为238.1 J·mm^(-3)时,试样的氮含量(质量分数)为0.76%,致密度为99.8%,抗拉强度为1275.0 MPa,延伸率为14.7%,力学性能最佳。合适的激光能量密度有助于提高材料的致密度,增加氮在材料中的溶解度,过饱和的氮在奥氏体晶格中起到固溶强化的作用,进而提升增材构件的抗拉强度及延伸率。变形过程中的形变诱导铁素体相变(DIFT)效应使部分奥氏体向铁素体转变,对材料的强度及韧性均有提升作用。Objective High-nitrogen steel has high strength, good corrosion resistance, and low cost. However, its difficulty in processing hinders its application. In this study, selective laser melting(SLM) is used to manufacture high-nitrogen stainless steel, which is suitable for manufacturing complex components and ensuring good mechanical properties. This study focuses on the effects of the laser volume energy density on the nitrogen content, relative density, phase composition, microstructure, and mechanical properties of manufactured samples.Methods In this study, the self-made high-nitrogen steel powder is used, and a vacuum heating furnace is used to dehydrate the powder before the experiment. Three laser parameters are designed for additive experiments. The nitrogen content and relative density of the specimens are measured after grinding and polishing. Phase analysis is performed using X-ray diffraction(XRD). The tensile strength is measured using a universal testing machine and the fracture morphologies of the tensile specimens are observed using scanning electron microscopy. The relationship between the microstructure and mechanical properties is studied. In addition, the phase compositions of the sample before and after a tensile test are measured using high-energy synchrotron XRD to analyze the strengthening mechanism.Results and Discussions The study shows that, when the laser volume energy density increases from190. 5 J·mm^(-3)to 285. 7 J·mm^(-3), the tensile properties first increase and then decrease(Fig. 9). When the laser power is 200 W, the laser scanning speed is 400 mm/s, and the laser volume energy density is 238. 1 J·mm^(-3), the specimen exhibits the best mechanical properties with the tensile strength of 1275. 0 MPa and elongation of 14. 7%. The nitrogen content(mass fraction) of the specimen reaches 0. 76%(Table 3), and the relative density of the specimen is 99. 8%(Fig. 6). An appropriate laser volume energy density can improve the relative density and increase the solubility of nitrogen in

关 键 词：激光技术 激光增材制造 高氮钢 选区激光熔化 显微组织 形变诱导铁素体转变 力学性能 

分 类 号：TB303[一般工业技术—材料科学与工程]