M. V. Chukin

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.

Protypology: A new stage in the standardization of metal products

Standardization is analyzed as a scientific discipline. The science of standardization may be referred to as protypology. On that basis, the stages in the development of standards for various types of carbon-steel products with ultrafine-grain structure are discussed.

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.

Influence of hybrid plastic deformation on the microstructure and mechanical properties of carbon-steel wire

Since the mechanical properties of metals and alloys with ultrafine-grain structure are of great practical interest, the development of continuous methods of intense plastic deformation deserves attention. The introduction of nanostructuring methods in existing production processes is subject to numerous constraints, mainly associated with the dimensions of the machined workpiece. Continuous methods of intense plastic deformation must be introduced, with corresponding gains of expediency and productivity. The combination of different types of plastic deformation is promising. Carbon-steel wire is studied in the present work. If drawing is combined with external loading, its applicability in wire production may be greatly expanded. If drawing is combined with flexure and torsion, a new production technology may be developed for the production of ultrafine-grain components. In this approach, continuously moving wire is subjected to tensile deformation (by drawing), flexural deformation (on passing through a system of rollers), and torsional deformation. The instruments employed are versatile and compatible with existing industrial equipment. If drawing is combined with flexure and torsion, the carbon-steel wire produced are characterized by ultrafinegrain structure. This approach permits modification of the mechanical properties of the wire over a broad range, without loss of strength or plasticity.

Creating ultrafine-grain structure in high-strength bimetallic steel-copper products

The benefits of continuous deformation of carbon wire are considered. Ultrafine-grain structure may be produced in carbon-steel wire with different carbon contents, so as to obtain a distinctive combination of strength and plasticity. The mechanical properties created in carbon-steel wire permit its use as the core of bimetallic wire used in contact systems for electric trains.

Influence of the Speed of High-Carbon Steel Billet in the Patenting Unit on Its Final Structure and Mechanical Properties

Prestressed ferroconcrete structures are widely used at present. As a result, compressive stress is created in the concrete and tensile stress in the reinforcing rope. The stressed reinforcing rope is better able to withstand the external loads that it experiences throughout the life of the construction. Consequently, larger loads may be applied or, with unchanged load, the size of the construction may be decreased, with accompanying savings of concrete and steel. Today, it is important to develop a manufacturing technology for nanostructured reinforcing rope that may be used in prestressed concrete-steel constructions. This technology is based on patenting, in which the steel acquires the structure of a fine ferrite–carbide mixture characterized by high strength and improved deformability. In the present work, the influence of increased billet speed in the patenting unit on the final structure and mechanical properties of steel 80, 70, and 50 is investigated, with a view to increasing the productivity in patenting, without loss of strength or plasticity of the steel, in the production of blanks for nanostructured reinforcing rope that may be used in prestressed concrete-steel constructions. To determine the heat-treatment time and temperature, the Gleeble 3500 system is used to plot diagrams of the isothermal decomposition of undercooled austenite. In qualitative and quantitative analysis of the microstructure, the interlamellar spacing of the ferrite–carbide mixture is determined for different billet speeds in the patenting system. The mechanical properties are studied in tensile tests. It is found that, for all billet speeds, the interlamellar spacing of the ferrite–carbide mixture is practically the same and is optimal for subsequent drawing: 0.1–0.2 μm. Thanks to the fine structure of the ferrite–carbide mixture formed in patenting, the strength of the billet is increased. Hence, in subsequent drawing, the billet may withstand greater compression without fracture. In the production of patented billet for nanostructured reinforcing rope, its speed in the patenting unit may be increased to 5 m/min. Consequently, the productivity may be increased without loss of strength and plasticity of the billet.

INFLUENCE OF HIGH-CARBON STEEL BILLET MOVEMENT SPEED IN PATENTENING UNIT ON STRUCTURE AND MECHANICAL PROPERTIES FORMATION

At present, intensive reinforced concrete constructions of various purposes have got considerable distribution, in which, as a rule, compressive stresses in concrete and stretching in the reinforcement are created. At the same time, the prestressed reinforcement better perceives the loads exerted on it by external forces during the whole lifetime of the construction, which allows increasing the load on the structure in comparison with the construction with non-tensioning reinforcement or at the same load value to reduce the dimensions of the construction and achieve savings in concrete and steel. One of the urgent problems of modern hardware production is considered to be development of the technology of nanostructured reinforcing ropes manufacturing, which are the main element of stressed reinforced concrete constructions for responsible use. The most important technological operation is patenting in which steel acquires the structure of a fine ferrite-carbide mixture (FCM), which has high strength and, at the same time, the deformation ability with large degrees of compression. The authors have investigated the effect of increasing speed of rod movement in the patenting unit on the structure and mechanical properties formation in steel of grades 80, 70 and 50 with the aim of determining the possibility to increase the productivity of the patenting unit without reducing the strength and plastic characteristics of steel in the production of nanostructured reinforcing ropes billets for reinforced concrete stressed constructions for responsible use. To determine temperature-time parameters of heat treatment, the isothermal diagram decomposition of the undercooled austenite was constructed using Gleeble 3500 research complex. A qualitative and quantitative analysis of the microstructure with the determination of the FCM interlamellar spacing was carried out at different speeds of the rod movement in the patenting unit. The mechanical properties under tension were tested. It was established that at all processing speeds, the values of the FCM interlamellar spacing in the range 0.1  –  0.2  μm are practically identical and optimal for the subsequent drawing. Due to the formation in the patenting of the disperse structure of FCM, an increase in the strength of the billet is achieved, which, with subsequent drawing, can withstand large crimps without breakage. It is shown that in the production of patented nanostructured billets for reinforcing ropes, one can increase the speed in patenting unit to 5 m/min without reduction of strength and plastic characteristics of the billet.

Analysis of the properties and functions of metal components

The properties of a metal component are analyzed and classified. It is established that the structure of the properties of some object may be described in terms of the determination of functions at different levels. The properties of metal components are analyzed and, on that basis, the concept of a function is defined. The concept of a component’s useful phase is introduced on the basis of the functional principle of property analysis. A design definition of the quality of metal products is proposed: the quality is the degree of fulfillment of three functions—transportation, installation, and operation. The methods of quality analysis based on investigation of the functions of the product over the duration of its useful phase also constitute the essence of functional–goal analysis. On the basis of this approach, the algorithm for quantitative quality assessment is improved. In the proposed approach, the stages of the life cycle are specified; the functions are arranged in a multilevel structure; and a single material body is regarded as a system of properties that will be differently expressed, depending on the purpose for which it is employed. Accordingly, functional–target analysis may be regarded as a new approach to studying the structure of the functions and properties of a metal component.

Status and Prospects of Deformational Methods For Refining the Microstructure of Bulk Materials

The current interest in obtaining metals and alloys with an ultrafine-grained structure is due to the qualitatively new level of their mechanical properties. Since an ultrafine-grained structure is formed as a result of high-rate plastic deformation (HPD), this article presents several alternative definitions of HPD. Continuous HPD methods are the methods that are of practical interest. However, several unresolved scientific-technical, technological, and organizational problems are making it necessary to resort to fundamentally new approaches to developing deformation-based methods of refining microstructural components. This article presents examples of the best-known continuous deformational methods of refining the structural components of metals and alloys. On the other hand, it is also necessary to consider that certain bulk metals and alloys with an ultrafine-grained structure have properties that limit or prevent their practical use. The results obtained from an analysis are used to determine the main avenues being pursued in the development of deformational methods of refining structural components. It is particularly important to consider the use of mini-mills, which can create technological systems based on integrated and consolidated components of modular equipment.

The Possibility of Manufacturing Long-Length Metal Products with Ultra-Fine Grain Structure by Combination of Strain Effects

It is shown that combination of strain effects leads to possessing the ultra-fine grain structure in carbon wire. The continuous method of wire deformation nanostructuring was developed on the basis of simultaneous applying of tension deformation by drawing, bending deformation when going through the system of rolls and torsional deformation on a continuously moving wire. One of the main advantages of the developed method is that various hardware devices and tools already applied for steel wire production can be used to implement this method thus simplifying its introduction to the current industrial equipment. The efficiency estimation of the developed continuous method of deformation nanostructuring was carried out using carbon wire with different carbon content. It is shown that the mechanical properties of the wire after combination of different kinds of strain can vary over a wide range. This method makes it possible to choose such modes of strain effect, which can provide the necessary combination of strength and ductile properties of carbon wire depending on its further processing modes and application.