Thermo-Mechanically Processed Multi-Phase Ductile Iron: Microstructure Development
Using thermo-mechanical simulator equipped with dilatometry system, two ductile iron alloys with different Mn-content are processed by combining both, well defined deformation process and subsequent controlled cooling in a single processing chain to control the final microstructure. Accordingly, ductile irons with four different structrues are produced namely, martensite, ausferrite, martensite+ferrite and ausferrite+ferrite. Depending on the dilatometric measurments, the ferrite formation temperature-range has been defined for both alloys. Preferential transformation of austenite to ferrite at graphite nodules during cooling is observed. It is also observed that the formation of ferrite during cooling results in both decreased martensite start of the undecomposed austenite and accelerated kinetics of ausferrite formation.
Adel Nofal and Mohamed Waly
M. Soliman et al., "Thermo-Mechanically Processed Multi-Phase Ductile Iron: Microstructure Development", Key Engineering Materials, Vol. 457, pp. 199-204, 2011