Microstructure transformation during plastic deformation of the austempered ductile iron

• Autorzy: Myszka D. , Olejnik L. , Kłębczyk M.
• Języki publikacji: EN

Abstrakty

EN

Excellent properties of ADI (Austempered Ductile Iron) are widely praised by the world technical literature. These properties depend on the cast iron microstructure formed during the heat treatment process of a specific type. The matrix of ADI is a mixture of lamellar ferrite and high-carbon austenite. It seems, however, that it is the austenite that is responsible for the high strength and ductility of this material, although investigations and analyses have proved that it is not homogeneous. Various types of austenite found in the ADI matrix include unreacted austenite, stable austenite, and metastable austenite which will be transferred into martensite during machining of castings. In this study an attempt has been made to determine the fraction of metastable austenite and to evaluate its effect on ADI properties. The heat treatment enabled manufacturing ADI characterised by the following properties: T.S.>1000MPa, El.>10%, Y.S.>600MPa. As a next step, the controlled process of plastic deformation of the samples was carried out. Applying the new method it has been established that due to 15% cold work, the structure of the examined ADI contains 9% of martensite; this volume fraction goes up to 17% after 25% cold work. The results of the investigations were cofirmed by X-ray diffraction pattern analysis and magnetic measurements. Consequently, it has been proved that ADI characterised by properties satisfying the criteria of an international standard developed for this particular material contains a large amount of metastable austenite subject to the TRIP (Transformation Induced Plasticity) effect.

Słowa kluczowe

EN

austempered ductile iron; TRIP (Transformation Induced Plasticity); cold work; microstructure; phase analysis

PL

żeliwo sferoidalne ausferrytyczne; zgniot; mikrostruktura; analiza fazowa

• Wydawca: Komisja Odlewnictwa Polskiej Akademii Nauk Oddział w Katowicach
• Czasopismo: Archives of Foundry Engineering
• Rocznik: 2009
• Tom: Vol. 9, iss. 1
• Strony: 169--174
• Opis fizyczny: Bibliogr. 11 poz., rys., tab., wykr.

Twórcy

autor

Myszka D.

autor

Olejnik L.

autor

Kłębczyk M.

• Institute of Precision Mechanics , Poland,

Bibliografia

• [1] Roedter H.: "ADI - Austempered Ductile Iron", Biuletyn Metals Minerals 2004, nr 2;
• [2] Hayrynen K.L., Keough J.R.: "Austempered Ductile Iron - The State of the Industry in 2003", Keith Millis Symposium on Ductile Cast Iron 2003, Livonia, Michigan, USA;
• [3] PN-EN1564, "Austempered Ductile Iron", 2000;
• [4] www.ductile.org[4] www.ductile.org
• [5] Jeleńkowski J.: "Kształtowanie struktury stali Fe-26Ni-2Ti z wykorzystaniem przemiany martenzytycznej", Oficyna Wydawnicza PW, Warszawa, 2005;
• [6] Biernacki R, Kozłowski J., Myszka D., Perzyk M.: "Prediction of properties of ADI assisted by artificial neural network", Materials Science (Medziagotyra), 2006, Vol.12, no 1, 11-15;
• [7] Zanardi F.: "The development of machinable ADI in Italy", Int. Scientific Conf. "Ductile Iron in 21st Century", Kraków, 2003;
• [8] Santos H., Pinto A., Torres V.: "Żeliwo sferoidalne ADI z dodatkiem Cu i Mn", Przegląd Odlewnictwa, 1992, no 3, 113-119.
• [9] Dymski St.: "Kształtowanie struktury i właściwości mechanicznych żeliwa sferoidalnego podczas izotermicznej przemiany bainitycznej", Wyd. Uczelniane ATR, Bydgoszcz, 1999;
• [10] Garin J. L., Mannheim R. L.: "Strain-induced martensite In ADI alloys", Journal of Materials Processing Technology, 2003, no 143-144, 347-351.
• [11] D.Myszka, T.Borowski, "ADI cyogenic treatment", Materials Science and Engineering, 2006, no 3, 221-224.