Microstructure and mechanical properties of a flash butt welded pearlitic rail
| Autor: | Leonardo Barbosa Godefroid, Gabriela Ribeiro Apolonio, Rodrigo Rangel Porcaro, Elisângela Silva Pinto, Luiz Cláudio Cândido, Geraldo Lúcio de Faria |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Austenite
0209 industrial biotechnology Heat-affected zone Materials science Cementite Metallurgy Metals and Alloys 02 engineering and technology Welding Industrial and Manufacturing Engineering Computer Science Applications law.invention Flash welding Grain growth chemistry.chemical_compound 020303 mechanical engineering & transports 020901 industrial engineering & automation 0203 mechanical engineering chemistry law Modeling and Simulation Ceramics and Composites Pearlite Hardenability |
| Zdroj: | Journal of Materials Processing Technology. 270:20-27 |
| ISSN: | 0924-0136 |
| DOI: | 10.1016/j.jmatprotec.2019.02.013 |
| Popis: | The structural changes resulting from the Flash Butt Welding (FBW) of pearlitic rails have been associated with wear/premature failures, despite this, there are no studies applying dilatometry to correlate the welding thermal cycles with the microstructural development of such material. The microstructural evolution of the heat affected zone is clarified with the aid of dilatometry. The increase in the steel hardenability associated with a larger austenitic grain size promotes the austenite-pearlite transformation at lower temperatures in the grain growth region. This explains why this region has larger pearlite colony size but smaller interlamellar pearlite spacing and higher hardness than the grain refined region. Partial cementite spheroidization in the heat affected zone is responsible for significant decrease in hardness and tensile strength and is correlated to localized dipping, rolling contact fatigue and failures. A dilatometry based methodology is proposed to define a process window and control the post-weld cooling rate at the rail head in order to improve the weld performance due to a better hardness profile, without increasing costs or welding time. For the steel evaluated, a 20% increase in the hardness of the softened area at the HAZ was obtained by dilatometric simulation of a safe accelerated cooling (5 °C/s). |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect