Effects of Vanadium on the Continuous Cooling Transformation of 0.7 %C Steel for Railway Wheels
| Autor: | Antonio J. Ramirez, Domingos José Minicucci, S.T. Fonseca, Paulo Roberto Mei, Conrado R. Afonso, Amilton Sinatora |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Austenite
Radiation Materials science Bainite Metallurgy Vanadium chemistry.chemical_element 02 engineering and technology engineering.material Continuous cooling transformation 021001 nanoscience & nanotechnology Condensed Matter Physics 020303 mechanical engineering & transports 0203 mechanical engineering chemistry Martensite engineering General Materials Science Microalloyed steel Pearlite 0210 nano-technology Hardenability |
| Zdroj: | Defect and Diffusion Forum. 367:60-67 |
| ISSN: | 1662-9507 |
| DOI: | 10.4028/www.scientific.net/ddf.367.60 |
| Popis: | To understand the effect of vanadium on the austenite decomposition of a 0.7 %C steel used in railway wheels the Continuous Cooling Transformation (CCT) diagrams were obtained and the microstructures analyzed with optical, SEM, TEM and XRD techniques. Vanadium refined the austenitic grain (12 and 6 μm for 7C and 7V, respectively), what can be explain by the presence of fine (10 nm in diameter) V4C3 precipitates, which restricts the austenitic grain growth. In addition, vanadium, in solid solution, reduced the pearlite interlamelar spacing (0.13 and 0.11 μm for 7C and 7V, respectively) by depressing the initial temperature pearlite formation (644 and 639 °C for 7C and 7V, respectively). He increased the ferrite volume fraction from 1 to 3 % at cooling rate of 1 oC/s, due the fact that vanadium is a ferrite stabilizer. Vanadium addition did not affect the initial temperature for martensite formation, but increased the hardenability with martensite formation at slower cooling rates (10 and 5 oC/s for 7C and 7V, respectively). For higher cooling rates (20 to 100 oC/s), the austenite transformation to martensite at room temperature was incomplete and all steels presented martensite and retained austenite, which volumetric fraction was near the same for both steels varying from 20 to 40 %. |
| Databáze: | OpenAIRE |
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