| XING Yuhan,YIN Yingyue,ZHANG Jianhua,YUE Xiaoming.Corrosion Resistance of SLM-fabricated Hastelloy X Alloy[J],53(6):67-79 |
| Corrosion Resistance of SLM-fabricated Hastelloy X Alloy |
| Received:March 24, 2023 Revised:July 03, 2023 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2024.06.006 |
| KeyWord:laser selective melting electrochemical machining Hastelloy X alloy microstructure electrochemical behavior |
| Author | Institution |
| XING Yuhan |
School of Mechanical Engineering, Shandong University, Jinan , China;National Demonstration Center for Experimental Mechanical Engineering Education, Key Laboratory of High Efficiency and Clean Mechanical Manufacture, Ministry of Education of China, Jinan , China |
| YIN Yingyue |
School of Mechanical Engineering, Shandong University, Jinan , China;National Demonstration Center for Experimental Mechanical Engineering Education, Key Laboratory of High Efficiency and Clean Mechanical Manufacture, Ministry of Education of China, Jinan , China |
| ZHANG Jianhua |
School of Mechanical Engineering, Shandong University, Jinan , China;National Demonstration Center for Experimental Mechanical Engineering Education, Key Laboratory of High Efficiency and Clean Mechanical Manufacture, Ministry of Education of China, Jinan , China |
| YUE Xiaoming |
School of Mechanical Engineering, Shandong University, Jinan , China;National Demonstration Center for Experimental Mechanical Engineering Education, Key Laboratory of High Efficiency and Clean Mechanical Manufacture, Ministry of Education of China, Jinan , China |
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| Abstract: |
| Electrochemical machining is a kind of non-traditional technology for the machining of difficult-to-cut alloy. It is widely used in modern industry by machining complex shape work pieces based on the electrochemical anodic dissolution reaction principle. The problem of low machining accuracy is normally caused by stray corrosion in electrochemical machining. In this paper, the effect of the microstructure on the corrosion resistance of SLM-fabricated Hastelloy X alloy during electrochemical machining (ECM) at low current density was investigated. A theoretical foundation was built to prevent stray corrosion on the surface of Hastelloy X alloy during electrochemical machining at low current density, and an outstanding machining accuracy was obtained. Scanning electron microscope images, Electron Backscatter Diffraction images and Electron probe X-ray microanalyser images of SLM-fabricated and wrought Hastelloy X alloy, were obtained with a scanning electron microscope and an electron probe X-ray microanalyzer equipped with electron backscattering diffraction. By analyzing the images of SLM-fabricated and wrought Hastelloy X alloy, it was found that there were differences in average grain size, subgrain boundary content and surface carbide precipitation. The optimized process parameters were determined by the compared measurement results of open circuit potential and polarization curve under low current density. Through integrating the temperature control and energy angle, the optimal process parameters of electrochemical machining under low current density were finally determined, so as to ensure that the alloy could be dissolved efficiently and stably without causing serious electrolyte loss and other problems resulting in energy waste. Key electrochemical parameters such as self-corrosion potential, passivation current density, polarization resistance, breakdown potential, were analyzed in the potentiodynamic polarization curves of SLM-fabricated and wrought Hastelloy X alloy, obtaining the influence law of microstructure characteristics on the corrosion resistance of SLM-fabricated and wrought Hastelloy X alloy during ECM processing at low current density. The results showed that SLM-fabricated Hastelloy X alloy had a finer grain size and less recrystallization ratio in comparison with the wrought counterparts. And a large number of dispersed M23C6 carbides were precipitated in the grain boundary and intragranular of the wrought Hastelloy X alloy. In addition, the SLM-fabricated Hastelloy X alloy existed a little corrosion current density of 2.01×10−6 A/cm2 and passive current density of 3.01×10−5 A/cm2 at the optimized processing parameter condition. Based on experimental results, it is concluded that SLM-fabricated Hastelloy X alloy has a finer microstructure and no M23C6 carbide precipitation, leading to lower self-etching current density and passivation current density compared with wrought Hastelloy X alloy under the same conditions. Therefore, it has higher anode passivation characteristics and higher corrosion resistance, and the passivation film is thicker and denser. The SLM-fabricated Hastelloy X alloy has high corrosion resistance in electrochemical machining, which can effectively inhibit the phenomenon of stray corrosion, and then achieve the purpose of improving the machining accuracy. The effect of microstructure on corrosion resistance of SLM-fabricated Hastelloy X alloy is analyzed and discussed in this paper, which lays a foundation for suppressing stray corrosion of nickel-based superalloy in the actual processing of electrochemical machining. |
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