Creep of the Matrix During Coalescence and Overgrowth of Graphite Precipitates in a High-Silicon Spheroidal Graphite Iron Submitted to Thermal Cycling in the Ferritic Domain

Tito Andriollo (1) , Jacques Lacaze (2) , Niels Tiedje (1)

1 Department of Health Technology, Technical University of Denmark
2 CIRIMAT - Centre interuniversitaire de recherche et d'ingenierie des matériaux

Thermal cycling of a high-silicon spheroidal graphite cast iron within the ferritic domain leads to coalescence of graphite particles with dendritic protuberances on the largest ones. This phenomenon occurs if there is some dissolution of graphite at the maximum temperature of the thermal cycle. Upon cooling, carbon redeposits in preferred locations, leading to the protuberances. This communication demonstrates that the ferritic matrix around the overgrowths can creep and remain in close contact with graphite. Thermal cycling of a high-silicon spheroidal graphite cast iron within the ferritic domain has recently been shown to lead to marked coalescence of graphite particles with the development of dendritic protuberances on the largest ones [1]. The alloy which was investigated consisted of 3.10 wt.% carbon, 4.45 wt.% silicon, 0.25 wt.% manganese and 0.0037 wt.% antimony (Fe balance) and had an as-cast fully ferritic matrix stable up to 850°C as verified with differential thermal analysis. Samples 2·10·10 mm 3 were subjected to thermal cycles which were each 480 seconds long and included a hold at 800°C±10°C for 60 seconds. The evolution of the microstructure was investigated after 1000, 2000 and 3000 cycles, this later value corresponding to a cumulative length of time at 800°C of 50 hours. Comparing the microstructure of the as-cast material in figure 1-a and after 2000 cycles in

Domaines: Matériaux

Tito Andriollo, Jacques Lacaze, Niels Tiedje. Creep of the Matrix During Coalescence and Overgrowth of Graphite Precipitates in a High-Silicon Spheroidal Graphite Iron Submitted to Thermal Cycling in the Ferritic Domain. Metallurgical and Materials Transactions A, 2020, 51, pp.2685-2688. ⟨10.1007/s11661-020-05727-y⟩. ⟨hal-02517975⟩