Observation of changes in the metallurgical characteristics of Ni-Cr alloys using Nd:YAG laser welding
- Department of Dental Laboratory Science, School of Dental Technology, Catholic University of Pusan, Busan, Republic of Korea
- Min-Ho Hong, Department of Dental Laboratory Science, School of Dental Technology, Catholic University of Pusan, 9 Bugok 3-Dong, Geumjeong-Gu, Busan 609-757, Republic of Korea. Email: mhhong{at}cup.ac.kr
Abstract
This study aimed to determine the effect of hardness change according to penetration depth in the laser fusing zone and observed the correlation of the microstructure as an Nd:YAG laser was irradiated to Ni-Cr alloy for dental use by setting the spot diameter size to various conditions. In all groups, the hardness depth profiles in the laser fusing zone and heat-affected zone (HAZ) had larger values than those of the base metal. In addition, the hardness values in places beyond the fusing zone and the HAZ were measured as being quantitatively lower. The observation result of the diffusion of the constituent elements and microstructure using field emission scanning electron microscopy, energy-dispersive spectroscopy, and electron probe microanalyzer showed that the fusing zone revealed a much finer dendritic form than the base metal due to the self-quenching effect after welding, while no change in constituent elements was found although some evaporation of the main elements was observed. In addition, Mo- and Si-combined intermetallic compounds were formed on the interdendritic area. Through this study, the laser fusing zone had better hardenability due to the intermetallic compound and grain refinement effect.
Article Notes
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Declaration of conflicting interests The authors declare that there is no conflict of interest.
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Funding This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
- Received April 17, 2014.
- Accepted June 25, 2014.
- © The Author(s) 2014
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