Influence of High Mn-Cu-Mo on Microstructure and Fatigue characteristics of Austempered Ductile Iron
| Autor: | M Banavasi Shashidhar, K S Ravishankar, S Naik Padmayya |
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| Rok vydání: | 2018 |
| Předmět: | |
| Zdroj: | IOP Conference Series: Materials Science and Engineering. 330:012020 |
| ISSN: | 1757-899X 1757-8981 |
| Popis: | The impacts of high Mn content on microstructure and fatigue characteristics of ADI at 300, 350 and 400 °C for 120 min have been examined. Optical microscopy images reveals bainite morphology only at 300°C. Higher Mn contents hinders bainite transformation in the locales of Mn and Mo segregation, where in stage II reaction initiates near the graphite nodules before stage I reaction ends away from the nodules which creates more unreacted austenite volume after cooling forming martensite around the periphery creating austenite-martensite zone at 350 °C and tremendously articulated at 400°C. Feathery ferrite laths, stable retained austenite and uniform density hardness in the matrix, promotes higher toughness and fatigue properties (250 MPa @ 106 cycles) at 300 °C. Presence of stage II carbides in the eutectic cell and austenite-martensite zone in the intercellular regions, due to their embrittlement in the matrix, makes easy crack path for initiation and propagation deteriorating properties at 350°C and above. SEM images of fatigue fractured surface revealed that at 300°C, showed a regular crack interconnecting graphite nodule, fatigue striation and quazi-cleavage fracture mode, and at 350 & 400°C reveals the carbide, austenite-martensite and porosity/defect final fracture region. |
| Databáze: | OpenAIRE |
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