Production of ADI by hot shake out—microstructure and mechanical properties

TLDR: In this paper, the authors investigated the production of ADI by direct austempering after hot shake out and found a procedure to obtain carbide free ductile iron in a permanent mold, to austemper the samples during the post solidification cooling stage, and to characterize the microstructure and mechanical properties of the resulting ADI.

Abstract: The present study investigates the production of ADI by direct austempering after hot shake out. The aims of the study are to find a procedure to obtain carbide free ductile iron in a permanent mold, to austemper the samples during the post solidification cooling stage, and to characterize the microstructure and mechanical properties of the resulting ADI.The requirements to obtain carbide free microstructures for the present experimental conditions were identified. The austempering thermal cycles were carried out after hot shake out by transferring the casting to a molten salt bath. The influence of the use of an intermediate temperature homogenization stage was also investigated. The microstructure and mechanical properties of hot shake out specimens, were compared to those corresponding to samples of the same heat, solidified and heat treated conventionally. The results show that coarser acicular structures are obtained after austempering during post solidification cooling, as a result of the difference...