Assessment of austenite static recrystallization and grain size evolution during multipass hot rolling of a niobium-microalloyed steel
Double-deformation isothermal tests and multipass continuous-cooling hot torsion tests were used to study the evolution of austenite microstructures during isothermal and non-isothermal hot deformation of an Nb microalloyed steel. These tests, coupled with microstructural characterization, have veri...
| Autores: | , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2009 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/56421 |
| Acceso en línea: | http://hdl.handle.net/10261/56421 |
| Access Level: | acceso abierto |
| Palabra clave: | Microalloyed steels Hot rolling Static recrystallization Austenite grain size Non-isothermal softening |
| Sumario: | Double-deformation isothermal tests and multipass continuous-cooling hot torsion tests were used to study the evolution of austenite microstructures during isothermal and non-isothermal hot deformation of an Nb microalloyed steel. These tests, coupled with microstructural characterization, have verified that the no-recrystallization temperature (Tnr) corresponds roughly to the temperature where recrystallization starts to be incomplete during rolling. An accurate method to estimate the recrystallized fraction during hot rolling based on stress-strain data, and which does not require metallographic studies, is proposed. The results of this method have been successfully compared to metallographic measurements, the values of non-isothermal fractional softening and the accumulated stress measured in the plots of mean flow stress (MFS) versus the inverse of temperature. A remarkable austenite grain refinement occurs in the first hot rolling passes after reheating. The correlation of isothermal and continuous cooling tests is better understood if the effect of grain size on recrystallization and precipitation is taken into account. |
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