| DANG Yuqin,LI Dongjie,LIU Yanmei,ZHAO Zhiwei,BAI Yunlong,KIM Kwang，Ho,LIAN Weifeng,WANG Ziming,WANG Tiegang.Microstructure and Corrosion Resistance of the Laser Cladding Layer on Nodular Cast Iron Surface[J],53(17):126-134, 145 |
| Microstructure and Corrosion Resistance of the Laser Cladding Layer on Nodular Cast Iron Surface |
| Received:February 06, 2024 Revised:July 03, 2024 |
| View Full Text View/Add Comment Download reader |
| DOI：10.16490/j.cnki.issn.1001-3660.2024.17.011 |
| KeyWord:laser cladding nodular cast iron Fe-base Ni-base corrosion resistance |
| Author | Institution |
| DANG Yuqin |
Tianjin Key Laboratory of High Speed Cutting and Precision Manufacturing, Tianjin University of Technology and Education, Tianjin , China |
| LI Dongjie |
Tianjin Huirui Laser Technology Co., Ltd., Tianjin , China |
| LIU Yanmei |
Tianjin Key Laboratory of High Speed Cutting and Precision Manufacturing, Tianjin University of Technology and Education, Tianjin , China |
| ZHAO Zhiwei |
Tianjin Key Laboratory of High Speed Cutting and Precision Manufacturing, Tianjin University of Technology and Education, Tianjin , China |
| BAI Yunlong |
CFHI Tianjin Heavy Industries Research & Development Co., Ltd., Tianjin , China |
| KIM Kwang，Ho |
Global Frontier R&D Center for Hybrid Interface Materials, Pusan National University, Busan 609-735, The Republic of Korea |
| LIAN Weifeng |
Chagnzhou NRB Corporation, Jiangsu Changzhou , China |
| WANG Ziming |
Chagnzhou NRB Corporation, Jiangsu Changzhou , China |
| WANG Tiegang |
Tianjin Key Laboratory of High Speed Cutting and Precision Manufacturing, Tianjin University of Technology and Education, Tianjin , China |
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| Abstract: |
| The work aims to solve the problem of short service life of ductile iron containers used for spent fuel storage due to corrosion on the inner wall, and to improve the surface corrosion resistance and wear resistance of ductile iron. Four different alloys, including 316L stainless steel, Ni625 alloy, 410L stainless steel, and NJ30 alloy, were prepared on the surface of ductile iron by powder feeding laser cladding technology. The microstructure, phase composition, element distribution, and corrosion morphology of the cladding layers were characterized by metallographic microscope, scanning electron microscope, and energy dispersive spectrometer. The microhardness and corrosion resistance of the cladding layers were tested by microhardness tester and electrochemical workstation. The results showed that all four cladding layers had good forming quality without cracks or obvious pores, and formed a good metallurgical bond with the substrate. The changes in the microstructure of the cladding layers from the bottom to the top included planar/cellular crystals, dendritic crystals, and equiaxed crystals. However, the middle part of the cladding layers of 316L stainless steel and Ni625 alloy had a smaller grain size. The microhardness of the deposited 316L, Ni625, 410L, and NJ30 was significantly higher than that of the substrate, which was 1.74, 1.92, 2.35, and 2.4 times that of the substrate, respectively. The hardness improvement of the 316L stainless steel and the Ni625 alloy cladding was attributed to solid solution strengthening, while the high hardness martensite phase generated inside the 410L stainless steel cladding and the generation of a large amount of precipitates inside the NJ30 alloy cladding were important reasons for their hardness improvement. According to the research, in a 3.5% NaCl solution, the self-corrosion potential relationship of the four cladding layers was 316L > Ni625 > 410L > NJ30, and the self-corrosion current density increased in turn, indicating that the corrosion resistance of the cladding layers decreased in turn. The results obtained from EIS impedance testing were highly consistent with those obtained from polarization testing. Combined with the results of element analysis, the γ-Fe phase rich in Cr and Ni elements was mainly generated inside the cladding layer of 316L stainless steel, and the γ-(Ni,Fe) solid solution, Cr2Ni3 phase, and M23C6 precipitate were mainly generated inside the cladding layer of Ni625 alloy. The rich Cr and Ni content inside the cladding layer enabled the formation of a higher quality metal passivation film on the surface, effectively improving the corrosion resistance of the material. Under the action of Mo elements, the corrosion resistance of the cladding layer of 316L stainless steel was further improved, and the self-corrosion potential reached the maximum value of the four cladding materials. Finally, the corrosion morphology of the samples showed that the surface of the cladding layer of 410L stainless steel and NJ30 alloy was severely corroded after electrochemical testing, while the surface of the cladding layer of 316L stainless steel and Ni625 alloy was flat and without obvious corrosion marks. In conclusion, the 316L and Ni625 alloy cladding layers have good comprehensive properties and are suitable for improving the surface modification of large ductile iron containers. |
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