Cementite dissolution in hypereutectoid steels containing Cr is analyzed using dilatometry combined with the consideration of the carbon content in the austenite. The results suggest that the austenite transformed from the mixture of ferrite and cementite can be approximated to have a carbon content corresponding to equilibrium with ferrite. The overall dissolution behavior of cementite is desc...

To support quantitative design of ultra-high-strength (UHS) secondary-hardening steels, the precipitation of cementite prior to the precipitation of the M2C phase is investigated using a model alloy. The microstructure of cementite is investigated by transmission electron microscopy (TEM) techniques. Consistent with earlier studies on tempering of Fe-C martensite, lattice imaging of cementite s...

perature range between 260° and 360°C. Jack showed that thin platelets of cementite formed at the beginning of this stage(10). In high carbon steels, the transformation twin interfaces are potent nucleation sites for the cementite formation and the cementite is related to the ferrite by Bagaryatskii's orientation relationship(2)(3)(11). Although there is no direct evidence of its existence in s...

High-silicon steels have long been known to possess exceptional resistance to tempering, but the reasons for this effect were unknown. We report here a study of the third stage of tempering of these steels, in which cementite is formed. In a 0.75 wt% C 1.4 wt% Si alloy steel, tempered for 1 hour at 380°C, it is found that silicon atoms are rejected from the growing cementite into the ferrite ma...

The mechanism by which relatively small concentrations of silicon influence the precipitation of cementite from carbon supersaturated austenite and ferrite are investigated. It is found that one condition for the retardation of cementite is that the latter must grow under para-equilibrium conditions, i.e. the silicon must be trapped in the cementite. However, this is not a sufficient condition ...

A long-standing challenge in physics is to understand why cementite is the predominant carbide in steel. Here we show that the prevalent formation of cementite can be explained only by considering its stability at elevated temperature. A systematic highly accurate quantum mechanical study was conducted on the stability of binary iron carbides. The calculations show that all the iron carbides ar...

Passing one electric-current pulse through deformed pearlitic steel wires at room temperature causes the formation of cementite particles around 30 nm in size. This is found not only in some particular locations but throughout the cementite area, which reveals a different mechanism from traditional spheroidization of cementite plates because the latter leads to the formation of particles with m...

We report results of gradient-corrected pseudopotential-based density functional theory calculations on bulk Fe3C in the cementite structure and its (0 0 1), (1 1 0), (0 1 1), (1 0 0), (1 0 1), (0 1 0), and (1 1 1) surfaces. Bulk properties are in reasonable agreement with available experimental data. The cementite local density of states shows predominantly metallic character, along with some ...

The decomposition of austenite to ferrite or cementite begins at the equilibrium phase boundary of austenite/ (ferrite austenite) or austenite/(cementite austenite) in binary Fe–C phase diagram. The temperature values on the phase boundaries of austenite/(ferrite austenite) and austenite/(cementite austenite) at a certain carbon content are called Ae3 and Acm temperatures of the steel, respecti...