Transient Directional Solidification of Cast Iron: Microstructure Formation, Columnar to Equiaxed Transition and Hardness

• Main Author: Spinola,Thiago Sartorello
• Publication Date: 2016
• Other Authors: Spinelli,José Eduardo
• Format: Article
• Language: eng
• Source: Materials research (São Carlos. Online)
• Download full: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392016000400795
• topic: cast iron; CET; hardness; microstructure; eutectic

A number of applications may require cast iron. Engine cylinder blocks, flywheels, gearbox cases, machine-tool bases may be manufactured by using grey cast iron while bearing surfaces with white cast iron. Thus, understanding the solidification behaviour of eutectic cast iron becomes an essential task, with certain points to be accomplished. Transient directional solidification may provide particular advantages in order to deal with these items, such as the large variation of growth rate (V) and cooling rate (Ṫ) values, which may allow a variety of microstructures and morphologies to be studied. The aim of this work is to examine the macrostructure regions, scale of the dendritic microstructure, proportions of the formed phases and hardness of samples obtained by transient directional solidification of a eutectic cast iron (Fe-3.5wt%C-2.5wt%Si). It was shown that a CET criterion should be based on a critical V value at the solidification front of about 0.6 mm/s. The effects of the formed phases, their proportions and λ2 on hardness of the cast alloy are assessed.