Spheroidal graphite cast iron GGG 40 was thermo-mechanically tested using thermo-mechanical simulator Gleeble-3500. Three deformation steps were successively applied on test-specimen at temperatures namely;900°C, 850°C and 750°C within the austenitic zone, at the same strain rate of 0.1 s-1. No cracks were observed, up to 50% deformation, after successive deformation steps. Stress-strain relationship obtained is correlated with previous work on SGCI with a different carbon equivalent. It was found that by decreasing the deformation temperature;for the same CE, young’s modulus, yield strength and strain hardening exponent increase. Microstructure of the deformed zone, for a specimen quenched after the final deformation step, reveals fine elongated ferrite and pearlite, as well as elongated graphite. While microstructure of the non-deformed zone subjected to the same treatment, includes coarser ferrite and pearlite with graphite spheres embedded in the matrix.
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