K. A. Gogaev

Production of Titanium Powder Sheets by Asymmetric Rolling

The influence of symmetric and asymmetric rolling on the formation and properties of titanium powder rolled sheets is studied. It is established that the asymmetric rolling of powder metal produces sheets with higher density and much better mechanical properties than symmetric rolling does. The effect of the titanium powder rolling conditions on the structure of the material before and after sintering is studied. The rolled metal obtained by asymmetric rolling has best mechanical properties at a sintering temperature lower by 200°C than that of symmetric rolling. The technological feasibility of asymmetric rolling of titanium powder is demonstrated.

Process Approaches for Producing Complex Composite Inoculants by Rolling of Powder Mixtures. I. Inoculant Powder Mixtures. Composition, Structure, and Properties

This series of papers are devoted to the development of process approaches for producing complex composite inoculants to manufacture agricultural machines from spheroidal graphite cast iron. Complex composite inoculants as strips and their fragments can be produced by rolling of powder mixtures. The first paper justifies the choice of inoculants and characterizes the starting powders they consist of. Weight and volume correlations between the brittle and ductile components for different compositions of inoculants are calculated. It is established that all powder compositions belong to critical systems that have approximately 50 vol.% of both brittle and ductile components. Such systems require special process approaches to make high-quality products. Process characteristics of the powders that influence the quality of the rolling strips are determined. These are apparent density of the starting powders and their mixtures, friction index (Hausner ratio), and shear angle and its tangent.

Contact stresses in the deformation zone and average pressure during asymmetric rolling of metal powders

Consideration is given to the contact normal stresses in the deformation zone on the drive rolls of different diameters rotating at the same angular speed during asymmetric rolling of iron and electrolytic titanium powders, as well as aluminum granules. The ratio of roll diameters is 1.12 to 1.42. It is established that the normal contact stresses on both rolls are much lower than those during conventional (symmetric) rolling. It is shown that during asymmetric rolling, the contact stress on the larger roll is lower than the stress on the smaller roll, regardless of the material being rolled and the density of the rolled product.

The Effect of Compacting Rolling on the Properties of Titanium Powder Mill Products

The effect of deformation stress on the consolidating of titanium powder strips obtained by symmetrical and asymmetrical rolling is analyzed. It is determined, that the strength of green strips after asymmetrical rolling is substantially higher than that of conventional strips: for low and medium deformation stress (by a factor of 3–5) and for high deformation stress (by a factor of >10). The repeated rolling improves the mechanical properties of sintered strips. Titanium powder strips produced through optimal asymmetrical rolling possess better mechanical properties than conventional titanium strips.

Finite-Element Optimization of the Asymmetric Rolling Process for Titanium Powder

The selection of resistance-to-deformation model is analyzed and justified. The results of mathematical modeling for the asymmetric rolling of titanium powder using the finite-element method are demonstrated.

Process Approaches for Producing Complex Composite Inoculants by Rolling of Powder Mixtures. II. Compacting Conditions, Structure, and Properties of Two-Component Model Systems Fe–FeSi and Al–FeSi

The optimization of compacting processes for two-component model systems consisting of brittle and plastic components is discussed. Fe–FeSi and Al–FeSi compositions with different volume content of the plastic component are tested. The compaction is conducted by pressing with different compacting force. Mechanical properties of cylindrical compacts are determined by axial compression test and the Brazilian test. It is established that the content of brittle component must be ≤ 60% and the compaction force must be ≥ 400 MPa. With increasing compaction force, the strength of the compacts increases significantly. It is established that the application of both iron and aluminum as binder is acceptable. However, iron and aluminum compositions are the best for low and high content of the brittle component, respectively.

Effect of Deformation Conditions on the Properties of Powder Material AMg5

The effect of deformation conditions on the structure and mechanical properties of powder materials based on aluminum-magnesium alloys produced by ultra-fast crystallization of a melt atomized by high-pressure water is studied. Extrusion of powder compacts into a strip that is then subjected to symmetric or asymmetric rolling is used as a deformation process. The effect of the rolling conditions on the mechanical properties of powder material AMg5 with Zr and Sc added is investigated. It is shown that the use of fractional rolling of strips made of AMg5 powder alloys significantly increases the ductility of the material and has a weaker effect on the strengthening; asymmetric rolling being more efficient than symmetric one.

Production of Co–Cr–Al–Y–Si powder alloys

A more effective process of producing the Co–Cr–Al–Y–Si powder with 40–100 mm particles has been developed. This process yields 70% of this powder fraction, while other existing processes provide 50–60%. The proposed process involves melting of ingots in an electron-beam unit and their subsequent fragmentation using a press and strip rolling mill. It is shown that energy consumption is lower during this mechanical grinding compared to the use of crushers and mills and is almost 20 times higher in atomization. The developed process is waste-free: 40 μm powder fraction is remetled in the ingot production process. The method of producing the Co–Cr–Al–Y–Si powder has been patented. The powder is used as a heat-resistant sublayer of thermal protection coatings for blades of gas turbine engines.

The Influence of Deformation Modes on the Structure and Properties of Al–Mg–X Powder Composites. I. The Influence of Rolling Conditions on the Mechanical Properties of Aluminum Powder Ribbons Strengthened with SiC Nanoparticles

The influence of deformation modes on the mechanical properties of metal matrix composites produced from the aluminum powder strengthened with SiC nanoparticles has been studied. Symmetric and asymmetric rolling processes were employed at room temperature. Rolling as an additional deformation processing step improves the composite structure by refining the SiC agglomerates, asymmetric rolling being a more effective deformation processing technique. This complex hardening mechanism allows the strength to be increased twofold without decrease in the elastic and ductile parameters.

Optimizing the Thermomechanical Processing of Spray-Formed Corrosion-Resistant Steel

The structure and properties of spray-formed corrosion-resistant steel 95Kh18 with subsequent thermomechanical processing are investigated. The optimal conditions for steel deformation and heat treatment are established. With increasing temperature of the rolled hot forming from 800 ± ± 20°C to 1100 ± 20°C, the steel impact strength increases from 80 to 260 kJ/m2.