Study on Hardness of Heat-Treated CoCrMo Alloy Recycled by Electron Beam Melting
The hardness of heat (thermally) treated CoCrMo ingots, recycled by electron beam melting and refining (EBMR) of a technogenic CoCrMo material (waste from the dental technology) under different process conditions (temperature and residence time) is examined. The heat treatment consists of two-step h...
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MDPI AG
2023-03-01
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| Online Access: | https://www.mdpi.com/1996-1944/16/7/2634 |
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| author | Katia Vutova Vladislava Stefanova Martin Markov Vania Vassileva |
| author_facet | Katia Vutova Vladislava Stefanova Martin Markov Vania Vassileva |
| author_sort | Katia Vutova |
| collection | DOAJ |
| description | The hardness of heat (thermally) treated CoCrMo ingots, recycled by electron beam melting and refining (EBMR) of a technogenic CoCrMo material (waste from the dental technology) under different process conditions (temperature and residence time) is examined. The heat treatment consists of two-step heating up to temperatures of 423 K and 1343 K and retention times of 40 and 60 min, respectively. The influence of various loads (0.98 N, 1.96 N, 2.94 N, 4.9 N, and 9.8 N) on the hardness of the CoCrMo alloy, recycled by EBMR, before and after heat treatment is studied. It has been found that regardless of the EBMR process conditions, the obtained samples after heat treatment have similar hardness values (between 494.2 HV and 505.9 HV) and they are significantly lower than the hardness of the specimens before the heat treatment. The highest hardness (600 HV) is measured in the alloy recycled at 1845 K refining temperature for 20 min. This is due to the smaller crystal structure of the resulting alloy and the higher cobalt content. The results obtained show that the heat treatment leads to considerable changes in the microstructure of the CoCrMo ingots recycled by EBMR. With the increase of the e-beam refining temperature, after the heat treatment, the grains’ size increases and the grains’ shape indicates an incomplete phase transition from γ-fcc to ε-hcp phase. This leads to a slight increase in the hardness of the alloy. |
| first_indexed | 2024-03-11T05:31:58Z |
| format | Article |
| id | doaj.art-90dd9c4494ac4d7ab7cac3d041113079 |
| institution | Directory Open Access Journal |
| issn | 1996-1944 |
| language | English |
| last_indexed | 2024-03-11T05:31:58Z |
| publishDate | 2023-03-01 |
| publisher | MDPI AG |
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| spelling | doaj.art-90dd9c4494ac4d7ab7cac3d0411130792023-11-17T17:02:49ZengMDPI AGMaterials1996-19442023-03-01167263410.3390/ma16072634Study on Hardness of Heat-Treated CoCrMo Alloy Recycled by Electron Beam MeltingKatia Vutova0Vladislava Stefanova1Martin Markov2Vania Vassileva3Institute of Electronics, Bulgarian Academy of Sciences, 1784 Sofia, BulgariaDepartment of Metallurgy of Non-Ferrous Metals and Semiconductors Technologies, University of Chemical Technology and Metallurgy, 1756 Sofia, BulgariaInstitute of Electronics, Bulgarian Academy of Sciences, 1784 Sofia, BulgariaInstitute of Electronics, Bulgarian Academy of Sciences, 1784 Sofia, BulgariaThe hardness of heat (thermally) treated CoCrMo ingots, recycled by electron beam melting and refining (EBMR) of a technogenic CoCrMo material (waste from the dental technology) under different process conditions (temperature and residence time) is examined. The heat treatment consists of two-step heating up to temperatures of 423 K and 1343 K and retention times of 40 and 60 min, respectively. The influence of various loads (0.98 N, 1.96 N, 2.94 N, 4.9 N, and 9.8 N) on the hardness of the CoCrMo alloy, recycled by EBMR, before and after heat treatment is studied. It has been found that regardless of the EBMR process conditions, the obtained samples after heat treatment have similar hardness values (between 494.2 HV and 505.9 HV) and they are significantly lower than the hardness of the specimens before the heat treatment. The highest hardness (600 HV) is measured in the alloy recycled at 1845 K refining temperature for 20 min. This is due to the smaller crystal structure of the resulting alloy and the higher cobalt content. The results obtained show that the heat treatment leads to considerable changes in the microstructure of the CoCrMo ingots recycled by EBMR. With the increase of the e-beam refining temperature, after the heat treatment, the grains’ size increases and the grains’ shape indicates an incomplete phase transition from γ-fcc to ε-hcp phase. This leads to a slight increase in the hardness of the alloy.https://www.mdpi.com/1996-1944/16/7/2634CoCrMo alloyelectron beam melting and refiningheat treatmenthardness |
| spellingShingle | Katia Vutova Vladislava Stefanova Martin Markov Vania Vassileva Study on Hardness of Heat-Treated CoCrMo Alloy Recycled by Electron Beam Melting Materials CoCrMo alloy electron beam melting and refining heat treatment hardness |
| title | Study on Hardness of Heat-Treated CoCrMo Alloy Recycled by Electron Beam Melting |
| title_full | Study on Hardness of Heat-Treated CoCrMo Alloy Recycled by Electron Beam Melting |
| title_fullStr | Study on Hardness of Heat-Treated CoCrMo Alloy Recycled by Electron Beam Melting |
| title_full_unstemmed | Study on Hardness of Heat-Treated CoCrMo Alloy Recycled by Electron Beam Melting |
| title_short | Study on Hardness of Heat-Treated CoCrMo Alloy Recycled by Electron Beam Melting |
| title_sort | study on hardness of heat treated cocrmo alloy recycled by electron beam melting |
| topic | CoCrMo alloy electron beam melting and refining heat treatment hardness |
| url | https://www.mdpi.com/1996-1944/16/7/2634 |
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