the influence of aluminium on the microstructure of austempered ductile cast iron (adi) has been studied. the presence of well distributed graphite in the matrix, and a relatively high volume fraction of retained austenite are responsible for the good mechanical properties of the aluminium alloyed austempered ductile irons including excellent wear resistance, higher resistance to thermal shock,...

The growth of niobium carbide in austenite involves the diffusion of both niobium and carbon. These elements diffuse at very different rates. A model is presented for the overall transformation kinetics of niobium carbide precipitation in austenite that takes into account the multicomponent nature of the diffusion process while at the same time allows for the curvature of the transformation fro...

grate bar is an industrial part which is used in the indurating furnace of an iron ore pelletizing plant. steel part ofthe grate bars are expected to have high resistance to atmospheric oxidation because of its contact with hot gases(up to 920 °c) during the normal operation of the process. in this study, different samples from several sections ofused grate bars with apparent defects were selec...

A thermodynamically-based precipitation model, employing the classical nucleation and growth theories, has been adapted to deal with simultaneous precipitation of metastable and stable phases. This model gives an estimation of the precipitation kinetics (time evolution of radius and density of precipitates for both phases, as well as the evolution of solute fraction) in a wide range of temperat...

Vapor grown carbon fiber reinforced pure aluminum matrix composites were fabricated by the hot-pressing method below the melting temperature of pure aluminum. The surface structures of the vapor grown carbon fibers and the interfacial structures between the fibers and the matrix in the composite were observed. The precipitation mechanism of crystalline aluminum carbide was also investigated. An...

Slight amounts of carbon (0:015{0:1mass%) were added into the Fe-30Mn-6Si-5Cr shape memory alloy. The microstructure, precipitation behaviour and shape memory performance of these Fe59Mn30Si6Cr5CX alloys with various thermo-mechanical treatments were investigated. Experimental results show that two particles, the -phase and M23C6 carbide, are observed within the grain-boundary phases. M23C6 car...

To achieve optimal mechanical properties in high manganese steels, the precipitation of nanoprecipitates of vanadium and niobium carbides is under investigation. It is shown that under controlled heat treatments between 850°C and 950°C following hot deformation, few-nanometre precipitates of either carbide can be produced in test steels with suitable contents of vanadium or niobium. The structu...

Nanoscale co-precipitation in a novel high-strength low-carbon steel is studied in detail after isothermal aging. Atom-probe tomography is utilized to quantify the co-precipitation of co-located Cu precipitates and M2C (M is any combination of Cr, Mo, Fe, or Ti) carbide strengthening precipitates. Coarsening of Cu precipitates is offset by the nucleation and growth of M2C carbide precipitate, r...

There is now a large volume of sophisticated steels which rely on silicon as an alloying addition with the purpose of avoiding the precipitation of cementite. But there is also evidence that the silicon can enhance the formation of ε–carbide; the mechanism of this effect is not understood and the absence of appropriate thermodynamic data makes it impossible to conduct calculations. We report he...