Influence of Strain Rate, Temperature and Chemical Composition on High Silicon Ductile Iron

Abstract

Today, the use of solution hardened ductile iron is limited by brittleness under certain conditions. If chassis components are subjected to loads having high strain rates exceeding those imposed during tensile testing at sub-zero temperatures, unexpected failure can occur. Therefore, it is the purpose of this review to discuss three main mechanisms, which have been related to brittle failure in high silicon irons: intercritical embrittlement, the integrity of the ferritic matrix and deformation mechanisms in the graphite. Intercritical embrittlement is mainly attributed to the formation of Mg- and S-rich grain boundary films. The formation of these films is suppressed if the amount of free Mg- and MgS-rich inclusions is limited by avoiding excess Mg and/or by the passivation of free Mg with P. If the grain boundary film is not suppressed, the high silicon iron has very low elongations in the shakeout temperature regime: 300 to 500 °C. The integrity and strength of the ferrite are limited by the reduced ordering of the silicumferrite with increasing silicon content, once the “ordinary” ferrite is saturated at 3% silicon, depending on the cooling conditions. Finally, the graphite damaging mechanisms are what dictate the properties most at low temperatures (sub −20 °C).

Influence of Austempering Temperatures on the Microstructure and Mechanical Properties of Austempered Ductile Cast Iron

“…so called onion-like mechanism, which is induced by graphite external shell coming from the reduced carbon solubility in γ phase during cooling [35]. The loss of graphite outer shell around the graphite nodule itself, in which the shell de-bonds from the nodule core, could be analyzed as a major failure mechanism [36]. The fracture surfaces of the samples were analyzed in order to determine the fracture mechanism at different austempering temperatures.…”

“…The loss of graphite outer shell around the graphite nodule itself, in which the shell de-bonds from the nodule core, could be analyzed as a major failure mechanism [36]. The fracture surfaces of the samples were analyzed in order to determine the fracture mechanism at different austempering temperatures.…”

Study on the Effects of Stress Corrosion Cracking (Scc) in Austenitic Stainless Steels – A Review

“…The welding of this material requires precision, without damaging its property, so special treatment were implied to weld stainless steel. The possibility of degradation of quality during welding is studied in this research review [1]- [3]. The stress in the region of welded region and its corrosion were studied.…”