Scrap metal: The problem of its shortage and efficient use

The most important element of manufacturing processes that employ new metallurgical technologies is improving the quality of the scrap metal used in the given process. Introducing modern scrap-processing equipment is especially important in this regard. At the same time, it is also necessary to use the latest technological advances in order to reduce the oxidation loss of iron during refining in arc steelmaking furnaces.     

Simulation of contact stresses and forces during hot rolling of thin wide strips with allowance for a stick zone and elastic regions in the deformation zone

A new procedure for the calculation of contact stresses and hot-rolling forces for wide strips 0.8–1.5 mm thick has been developed and tested. This procedure takes into account the presence of a stick zone in the deformation zone and stress distributions in both elastic and plastic regions in the deformation zone. The average error in the force calculation according to the new procedure is 5%, which is more than two times smaller than the calculation error of well-known force calculation procedures. The developed procedure is used to simulate the contact stresses in the deformation zones of working stands in a six-stand 1700 mill during rolling of strips thinner than 1.0 mm. A number of new relations for the state of stress in a strip have been revealed upon simulation. Some of these relations are as follows: in the last stands, the length of elastic regions accounts for 10–17% of the total deformation-zone length; the maximum normal contact stresses are 1300–1400 MPa, which corresponds to the stresses in the deformation zones of cold-rolling mills; the stick-zone length accounts for 85–99% of the deformation-zone length; and the contact stresses in the stick zone are virtually independent of the friction coefficient. The developed calculation procedure can be used to optimize the technological regimes of wide-strip mills.     

An assessment of the θ-projection method for the representation and extrapolation of creep data for a 1%Cr, 12%Mo, 14%V steel tested at 565°C

Constant stress creep data for a wrought 1%Cr, $\text{1}\text{2}\text{\%}\text{Mo}$, $\text{1}\text{4}\text{\%}\text{V}$ steel obtained from six tests carried out at 565°C have been fitted and extrapolated using the θ-projection method. Creep curves for high stresses were fitted well, but curves extrapolated to stress levels below those used in the θ-projection did not represent well the available data for primary-secondary creep. To enable a satisfactory extrapolation of results, it was found necessary to redefine the failure condition to be less sensitive to the shape of the latter sections of the tertiary creep curve. This was achieved by defining lifetime as the point on the curve at which the strain rate reached a fixed multiple of the creep rate at half the rupture time. The extrapolated data compare well with the results of tests carried out independently on a cast 1%Cr, $\text{1}\text{2}\text{\%}\text{Mo}$, $\text{1}\text{4}\text{\%}\text{V}$ steel. The extrapolation procedure not only predicts the ‘knee’ in the log stress-log lifetime curve but allows extrapolation of lifetimes by over a factor of thirty. In addition, acceptable predictions have been made of constant load experimental data.     

Preliminary model of the Ribeira Grande geothermal field (Azores Islands)

On the basis of a geological - volcanological - geophysical survey, integrated with petrological and geochronological data, a structural model, including a shallow magmatic body, was defined for the Ribeira Grande area, Sao Miguel island (Azores). Two series of production tests were carried out in the Pico Vermelho 1 and Ribeira Grande 1 wells, which led to a preliminary definition of the deep fluid circulation. The data obtained from these studies were used to reconstruct a preliminary model of the Ribeira Grande geothermal field.     

Synthesis and properties of zinc nanoparticles: The role and prospects of radiation chemistry in the development of modern nanotechnology

Zinc-containing nanoparticles stable in the liquid phase are synthesized by the radiation chemical reduction of zinc ions in solutions of inverse micelles. The effects of the absorbed radiation dose and the size of the micelle water pool on the spectral characteristics of samples are studied. The HPLC and electron microscopy results indicate that the composition of nanoparticles synthesized depends on the salt nature. Original Russian Text ? A.A. Revina, E.V. Oksentyuk, A.A. Fenin, 2007, published in Zashchita Metallov, 2007, Vol. 43, No. 6, pp. 613–618.     

Effect of cationic surfactant and inorganic anions on the electrochemical behavior of carbon steel in formation water

Corrosion behavior of carbon steel in formation water associated crude oil from Egyptian western desert was studied at various concentrations of dodecyl dimethyl ammonium chloride (CS) as a cationic surfactant. Polarization curves indicate that CS has a good inhibition efficiency for carbon steel in formation water and behaves as cathodic inhibitor. The inhibition efficiency was found to increase with increase in CS concentration until reaches a maximum constant value corresponding to the critical micelle concentration of CS and decrease with increase in solution temperature. The adsorption of CS follows the kinetic thermodynamic model and Flory-Huggins isotherm. Thermodynamic parameters obtained indicate that that the presence of the CS increases the activation energy. Polarization and Impedance measurements indicate that the addition of KI has a significant synergistic effect with CS and results in increase the inhibition efficiency of CS in formation water.