Evaluation of the Corrosion Resistance of Tubing of Various Strength Groups

Metallurgist - The corrosion resistance of tubing pipes of four strength groups is evaluated: E, Λ, K and D by measuring the saturation current density of steel anodic dissolution. It is shown...     

Crystal and Defect Structure of Nd1.9Ce0.1CuO4±y

The crystal and defect structure of neodymium cerium cu-prate (Nd_1.9 Ce_0.1 CuO_4±y) has been studied as a function of temperature (1200–1500 K) and oxygen pressure (10⁰–10³ atm) via X-ray diffractometry, powder neutron diffraction, and thermogravimetry methods. The oxygen nonstoichiom-etry changes from oxygen-excess (positive y values) to oxygen- deficient oxides (negative y values). The absolute values of oxygen nonstoichiometry y are calculated from the neu-tron diffraction and thermogravimetry data. The materials adopt the tetragonal structure (space group I 4/ mmm ). A defect model is proposed for Nd_2-x Ce_x CuO_4±y. It is con-cluded that oxygen vacancies V Ö (which occupy O(1) crys-tallographic positions (in planes)) and interstitial oxygen O(i (which occupy O(3) "apical" positions) are present simultaneously. Gaseous oxygen intercalates into the Nd_1.9 Ce_0.1 CuO_4±y crystals and replaces oxygen vacancies in the O(1) position and interstitial oxygen atoms in the O(3) positions. The theoretical model and the experimental data are in good agreement with each other, and the equilibrium constants of defect formation have been calculated.     

The Effect of Errors of the Form and Position of the Base Surfaces of a Composite Axisymmetric Body on the Size of an Adjacent Contour

Measurement Techniques - The influence of errors of form (ovalities) of the base surfaces of a composite axisymmetric body on the size of an adjacent contour was studied. It was proved that...     

Complex optimization of arc melting synthesis for bulk Cr2AlC MAX-phase

A complex optimization of the arc melting synthetic approach was performed to enhance the phase purity of Cr₂AlC MAX-phase in the bulk form. Optimization steps included the initial ratio of 2Cr: xAl: 1C, variation through a change in Al content (i.e. x ranging from 1 to 1.5), tuning duration of the post-annealing thermal treatment and adjustment of the melting chamber pressure. The use of Cr₃C₂ as a precursor in place of Cr and C mixture has also been tried. It was found that Cr₂AlC MAX-phase forms as the predominant phase when a stoichiometric ratio 2Cr: 1.3Al: 1C is used. By keeping this stoichiometry constant, the melting chamber pressure was then adjusted to further improve the phase purity of the samples. It has been established that the use of Cr₃C₂ is not an appropriate way to improve sample purity and promote homogeneity in the carbon distribution. The establishment of an optimized arc fusion protocol for parental Cr₂AlC is a necessity for further successful mass synthesis of the substituted (Cr_1-xMn_x)₂AlC MAX-phase.     

Effect of Production Technological Parameters on Corrosion Resistance of Ultralow-Carbon Cold-Rolled IF-Steels

Metallurgist - The influence of production technological parameters on corrosion resistance of cold-rolled ultralow-carbon IF-steels of various compositions (0.003–0.005 wt.% C,...     

Influence of impurities on the solid-solution hardening of low-carbon steel

The influence of impurities on the solid-solution hardening of cold-rolled low-carbon steel components is considered, by calculation and experiment. To confirm the results, data regarding the influence of the chemical composition on the properties of cold-rolled 08?? steel components (produced by Cherepovets Metallurgical Works, OAO Severstal??) are subjected to statistical analysis, with the formulation of a regression model. The factors that underlie the influence of impurities on the properties of 08?? steel are investigated, and the optimal impurity contents for products of the highest extrusion category are established.