Strengthening mechanisms of solid solution and precipitation at elevated temperature in fire-resistant steels and the effects of Mo and Nb addition
| Autor: | Jun-Ho Chung, Joonoh Moon, Hyun-Uk Hong, Chang-Hoon Lee, Sung-Dae Kim, Hyo-Haeng Jo, Bong Ho Lee |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
Constant-load test
Fire-resistant steel Mining engineering. Metallurgy Materials science Precipitation (chemistry) TN1-997 Metals and Alloys Atom probe High-temperature strength Surfaces Coatings and Films Carbide law.invention Biomaterials Dislocation annihilation Transmission electron microscopy law Ceramics and Composites Strengthening mechanism Composite material Dislocation Deformation (engineering) Strengthening mechanisms of materials Solid solution |
| Zdroj: | Journal of Materials Research and Technology, Vol 15, Iss, Pp 5095-5105 (2021) |
| ISSN: | 2238-7854 |
| Popis: | Fire–resistant properties of Mo-/Nb-added structural steels were evaluated using hot tension tests and constant-load tests. Hot tension tests showed that an increase in the Mo and Nb contents led to a slow decrease in the strength as the holding time increased at a high temperature (600 °C), enhancing the fire resistance. Transmission electron microscopy (TEM) and atom probe tomography analyses revealed that this improved fire resistance stemmed from the annihilation of dislocations at high temperatures, which was suppressed by the solid solution of Mo atoms and fine precipitation of Ti/Nb-enriched MC carbides. Meanwhile, an increase in Ti content decreased fire resistance via precipitation of coarse TiC particles, i.e., in-situ TEM observations showed that dislocations moved easily along the surface of coarse particles by climb, indicating that coarse particles did not play a role in disturbing dislocation movement during deformation at high temperatures. Next, constant-load tests were carried out with a constant load of 50% of the yield strength, while the temperature was increased linearly until failure. The results were in good agreement with the results of the hot tension tests; i.e., the failure temperature increased with an increase in the Mo and Nb contents, indicating improvement in fire resistance. |
| Databáze: | OpenAIRE |
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