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Electron microstructure and mechanical properties of silicon and aluminum ductile irons

Journal Article · · Acta Metallurgica et Materialia; (United States)
 [1]; ;  [2]
  1. Univ. of Novi Sad (Yugoslavia). Dept. of Production Engineering
  2. Univ. of Birmingham (United Kingdom). School of Metallurgy and Materials

Samples of unalloyed silicon and aluminum spheroidal graphite cast iron have been studied in the austempered condition. Austempering times of up to 3 h at 400 C for Al SG and 1 h at 350 C for Si SG gives a typical ADI microstructure consisting of carbide-free bainitic ferrite and stable, high carbon enriched, retained austenite. This has an attractive combination of elongation and strength. For longer austempering times transition carbides are precipitated in the bainitic ferrite, [eta]-carbide in the upper bainitic range, i.e. 400 C for Al SG and 350 C for Si SG, and [epsilon]-carbide in the lower bainite range. Increasing amounts of transition carbide reduce the ductility and produce a mixed mode of fracture. For longer austempering times [chi]-carbide is precipitated at the ferrite/austenite boundaries leading to a more brittle fracture mode.

OSTI ID:
6976262
Journal Information:
Acta Metallurgica et Materialia; (United States), Journal Name: Acta Metallurgica et Materialia; (United States) Vol. 42:9; ISSN 0956-7151; ISSN AMATEB
Country of Publication:
United States
Language:
English

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