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Study on the white layer in wire electrical discharge trim cutting of bearing steel GCr15

  • Zhi ChenEmail author
ORIGINAL ARTICLE
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Abstract

In wire electrical discharge machining (WEDM), a large amount of thermal energy is produced to remove workpiece material, and a certain thickness of white layer is also generated in this process. The white layer has a significantly negative effect on the reliability and service life of workpiece. Hence, predicting and decreasing white layer are important to evaluate and improve the performance of workpiece. In this paper, a multi-pulse thermal model is proposed to obtain the temperature distribution of workpiece during the trim cutting bearing steel GCr15. The temperature measurement experiment demonstrates that this thermal model is feasible and reliable. Additionally, a set of experiments are implemented to reveal the formation mechanism of white layer, such as microstructure observation, XRD measurement, and microhardness measurement. It can be found that the white layer has high microhardness due to high content of Fe3C. The black layer has low microhardness because of high content of retained austenite. In addition, the white layer thickness (WLT) of workpiece is predicted with high precision according to temperature distribution and the critical temperatures of metallographic transformation. Furthermore, the magnetic-assisted method is presented to reduce abnormal discharge status and WLT, and the WLT can be decreased as low as 5 μm.

Keywords

WEDM White layer Thermal model Formation mechanism Magnetic-assisted method 

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Notes

Funding information

This research is supported by the National Natural Science Foundation of China (Grant No. 51805552 and No. 51575533) and the Project of State Key Laboratory of High Performance Complex Manufacturing, Central South University No. ZZYJKT2018-10.

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Copyright information

© Springer-Verlag London Ltd., part of Springer Nature 2019

Authors and Affiliations

  1. 1.State Key Laboratory of High Performance Complex Manufacturing, College of Mechanical and Electrical EngineeringCentral South UniversityChangshaPeople’s Republic of China

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