大厚度高氮钢多层多道等离子弧增材构件的组织与性能分析  

Microstructure and Mechanical Properties of the Large Thickness High Nitrogen Austenitic Stainless Steel Component Deposited by Multi-layer and Multi-pass Plasma Arc Additive Manufacturing Process

作　　者：孙跃 冯曰海[1,2] 刘思余 王克鸿[1,2] SUN Yue;FENG Yuehai;LIU Siyu;WANG Kehong(School of Materials Science and Engineering,Nanjing University of Science and Technology,Nanjing 210094,China;MIIT Key Laboratory of Intelligent Controlled-arc Additive Manufacturing,Nanjing University of Science and Technology,Nanjing 210094,China)

机构地区：[1]南京理工大学材料科学与工程学院,南京210094 [2]南京理工大学工业和信息化部受控电弧增材制造与焊接重点实验室,南京210094

出　　处：《材料导报》2020年第22期22118-22123,共6页Materials Reports

基　　金：国家部委项目(17-H863);国防研究项目(41423050125)。

摘　　要：以自研的高氮奥氏体不锈钢焊丝为增材丝材,采用等离子弧成功堆敷了25 mm大厚度高氮钢构件。采用X射线检测、光学显微镜、扫描电镜、能谱仪和机械试验机对增材构件的缺陷、成分、组织和力学性能进行了检测分析,详细考察了堆敷速度对组织和力学性能的影响,揭示了大厚度多层多道增材制造的组织变化规律和性能增强机制。结果表明:大厚度高氮钢增材构件内部存在少量气孔,并且构件内合金元素分布均匀。试样的组织大部分为奥氏体,还有少量的δ铁素体和弥散分布的氮化物,层间和道间均分布着铁素体带。当堆敷速度由30 cm/min下降到18 cm/min时,上下两层相邻焊道交界处铁素体带的宽度由160μm降低到35μm,每层热输入量由1.275×104 kJ降到1.042×104 kJ;试样的横向和纵向平均抗拉强度分别提高90 MPa、76 MPa,横向和纵向平均延伸率分别提高6.5%、7.0%,横向和纵向平均冲击韧度分别提高12.07 J/cm 2、4.02 J/cm 2,试样的平均显微硬度提高了22.2HV。High nitrogen austenitic stainless steel(HNS)components of 25 mm thick were deposited successfully by wire and plasma arc additive manufacturing process,in which the self-developed HNS wire is selected as the filling material.Then weld defects,chemical composition,microstructures and mechanical properties of HNS components were tested and analyzed by X-ray detection,SEM,EDS and mechanical testing machine.Moreover,the influences of deposited speed on microstructure and mechanical properties were investigated in details,then the microstructure evolution and enhancement mechanism of multi-layer and multi-pass additive manufacturing process were revealed.Experiment results show that only few tiny pores are found in the deposited samples,and all the alloy elements is evenly distributed in deposited components.The microstructure of the effective deposited layers is composed of large amount of austenite,few d-ferrite and some nitrides.Meanwhile,lots of ferrite bands are also found at the interfaces of both adjacent deposited layers and adjacent deposited beads.Furthermore,with the deposited speed reducing from 30 cm/min to 18 cm/min,the width of the ferrite band between the upper and lower layers decreases from 160μm to 35μm,and the heat input of each deposited layer decreases from 1.275×104 kJ to 1.042×104 kJ.In addition,the ultimate tensile strength of the deposited samples in horizontal direction and that in vertical direction individually increased by 90 MPa and 76 MPa on an average,the mean elongation in both horizontal direction and vertical direction individually improved by 6.5%and 7.0%,and the average impact toughness in two directions individually enhanced by 12.07 J/cm 2 and 4.02 J/cm 2.Hardness testing results exhibited the microhardness of the HNS samples raised by 22.2 HV on an average.

关 键 词：高氮钢 等离子弧增材 多层多道 显微组织 力学性能 

分 类 号：TG456.2[金属学及工艺—焊接]