A. G. Korchunov

Numerical Study of Grain Evolution and Dislocation Density during Asymmetric Rolling of Aluminum Alloy 7075

The paper gives a mathematical model of grain evolution and dislocation density during asymmetric cold rolling of aluminum alloy 7075 in an SPD mode. Correlations between the effect of equivalent and shear strain on Al 7075 structure are obtained. An agreement of simulation results with experimental data is shown.

Finite Element Modeling of Shear Strain in Rolling with Velocity Asymmetry in Multi-Roll Calibers

Severe plastic deformation is now recognized the most efficient way of producing ultrafine grained metals and alloys. At the present time a lot of severe plastic deformation methods have been proposed and developed. They differ in the deformation schemes. Unlike such severe plastic deformation methods as high pressure torsion and equal-channel angular pressing, rolling with the velocity asymmetry is a continuous process. It helps to solve the problem of the limited length of manufactured bars with semi ultrafine structure. Rolling process with roll velocity asymmetry generates high shear strain necessary for obtaining ultrafine structures of the processed material. A new process of asymmetric rolling of profiles in multi-roll passes has been developed. This process can be used for production of high-strength profiles such as circles, hexagons, wire rods, etc. Compression of the bar in multi-roll passes can be done not only from two, as usual, but from three or four sides. In case of a multi-crimped bar, a uniform compression scheme with large hydrostatic pressure is created in the deformation zone. It enhances the ductility of the material and allows increasing the strain intensity. Simulation in DEFORM 3DTM proved that the process of asymmetric rolling in multi-roll calibers allows to obtain higher values of shear strain and strain effective.

Forming ultrafine-grain structure in steel wire by continuous deformation

Attention focuses on means of increasing the strength of steel wire, without loss of plasticity. A fundamentally new continuous method of free extension in bent uniform channels permits the formation of ultrafine-grain wire structure.

Multiscale Computer Simulation of Drawing with Statistical Representation of TRIP Steel Microstructure

The drawing of TRIP steel rod is analyzed. Such steel offers a range of performance benefits. For the case where the microstructure of TRIP steel must be taken into account, problems with traditional process design based on finite-element computer simulation are noted. By means of multiscale simulation, the microstructure of the steel and the dynamic structural and phase transformations (the TRIP effect) may be taken into account. The proposed approach to multiscale modeling is tested for the drawing of TRIP 700 steel in a traditional system. The possibility of controlling the distribution of the steel’s properties by means of the process parameters is assessed. By the proposed method, the deformational interaction of the microstructural elements of TRIP steel may be studied, and the computer resources required by the model may be dramatically decreased.

Variation in the mechanical properties of high-strength rebar during the production process

The variation in strength and plastic properties of high-strength rebar (diameter 9.6 mm) for use in ferroconcrete cross ties is traced through the production process. The contribution of each operation to the specified rebar quality is assessed.

Methodology of Developing Mathematical Models for Quality Indices Control

It is proposed to set the structure of metal products quality as a hierarchical tree of properties. Input and output variables and also control parameters of technological processes are represented as universal multitudes in formalization of the process of production quality indices handling in hardware industry technologies. Presence of simultaneously diversified information initiating different types of independence, is characteristic of solving problems of metal products quality indices control.

Assessing the effectiveness of intense plastic deformation of structural carbon steel

The production of a specified ultrafine-grain structure and mechanical properties of carbon steel in intense plastic deformation is formalized. Stochastic and statistical models are considered for the description of intense plastic deformation with different degrees of information regarding the relation between the control parameters and the mechanical properties of carbon steel with ultrafine-grain structure. A new approach is developed for assessing the effectiveness of intense plastic deformation of carbon steel.

Controlling the structure and properties of nanostructural carbon steel

A control algorithm is proposed for the structure and properties of nanostructural carbon steel in intense plastic deformation. The formalization of the control problem takes account of the indeterminate character of the state parameters and mechanical properties of the nanostructural carbon steel.

Shaping high-strength rebar for redesigned ferroconcrete cross ties

Cold deformation of high-strength rebar is considered. By statistical control methods, control charts are formulated for the shaping of a periodic rebar profile by two technologies. Two-section, six-roller drawing cells prove preferable to single-section, three-roller cells.