METALS AND METAL MATRIX COMPOSITES |
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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 |
SUN Yue1,2, FENG Yuehai1,2, LIU Siyu1, WANG Kehong1,2
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1 School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China 2 MIIT Key Laboratory of Intelligent Controlled-arc Additive Manufacturing, Nanjing University of Science and Technology, Nanjing 210094, China |
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Abstract 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 160 μm to 35 μm, 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/cm2 and 4.02 J/cm2. Hardness testing results exhibited the microhardness of the HNS samples raised by 22.2 HV on an average.
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Published: 02 December 2020
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Fund:This work was financially supported by the National Defense Innovation Project Foundation of China (17-H863), the Ministry Equipment Pre-research Project Foundation of China (41423050125). |
About author:: Yue Sunreceived his B.S. degree in material forming and control engineering from Nanjing University of Science and Technology in 2017.He is currently pur-suing his M.S. at School of Materials Science and Engineering, Nanjing University of Science and Technology under the supervision of A.P. Yuehai Feng. His research interest is plasma arc additive manufacturing process, advanced welding methods and processes.Yuehai Feng, doctor of engineering, associate professor of Nanjing University of Science and Technology, master instructor. He performed collaborative research from 2014 to 2015 in Welding and Laser engineering Research Centre of Cranfield University. He concentrated on researches about advanced welding process, controlled-arc additive manufacturing, automatic wel-ding equipment, welding process control system design and through-arc process sensing and control. He authorized more than 20 invention patents; published SCI, EI included more than 30 articles; won the second prize of the Jiangsu provincial science and technology and second prize of military science and technology process. |
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