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A technique for simplified simulation of the forging of large ingots using modern machine-learning methods for constructing models that describe stages of thermomechanical processing is described. [ABSTRACT FROM AUTHOR]

Three stages are developed for forming a Damascus steel structure of high-purity white cast iron BU22A obtained by vacuum melting. In the first stage of the production process, a continuous of carbide sheath is formed along the boundaries of austenitic grains, which morphologically resembles ledeburite inclusions. In the second stage of the process, there is compaction and faceting of large eutectic type carbide formation. In the third stage of the production process (forging), a globular sorbite matrix is formed with faceted eutectic carbides in size from 5.0 to 20 μm distributed unevenly in the deformation direction. It is observed that the stoichiometric composition of faceted eutectic carbides is within the limits of 34 < C < 36 at.%, which corresponds to Fe2C type ε-carbide with a hexagonal close-packed lattice. A two-stage mechanism is considered for conversion of excess secondary cementite into faceted Fe2C type eutectic ε-carbides. It is revealed that isothermal exposure duration on heating to the eutectic temperature, is an integral part of the process of forming new excess Fe2C type carbides with a hexagonal close-packed lattice. [ABSTRACT FROM AUTHOR]

We study the technological specific features of the production of steel ingots without zonal chemical inhomogeneity aimed at manufacturing the billets of various parts of power-generating units made of 15KhN3MFA and 15Kh2MFA steels. The technology of pouring in a vacuum is developed with regard for the results of the numerical analysis of the process of solidification of a steel ingot 13.56 tons in weight by using the Poligon system of automatized modeling of the pouring processes. In order to get high-quality ingots, steel was melted in an EAF-12 according to a special technology guaranteeing low contents of sulfur, phosphorus, nonmetallic inclusions, and hydrogen. The specific structural features of an ingot with a mean diameter of 922 mm and the ratio H/D = 2.05 are taken into account in the development of the technology of forging in a 3000-ton press. Forging is performed for billets 900 × 930 × 1200 mm in size with the axial channel located at the top of the billets. To avoid confusions, sulfur prints were made from the top and bottom surfaces of the billet. The investigations demonstrate that the sulfur prints are practically identical for both surfaces, and small separate sulfur inclusions are uniformly distributed. The macrostructure corresponds to the GOST-10243. The results of UT testing demonstrate that the billets of the parts contain no defects with an area greater than 5 mm2. The mechanical properties at temperatures 20°C and 350°C are practically identical and higher more than the requirements of normative documents by 15-20%. For the additional metallurgical quality examination of the metal, we manufactured a test shell with a height of 1100 mm, an outer diameter of 870 mm, and a wall thickness of 250 mm. [ABSTRACT FROM AUTHOR]

The rational use of metal is determined by the use of alternative methods to produce blanks, including forging a crystallizing metal. Application of external pressure to the melt during crystallization completely eliminates gas porosity, which improves the mechanical characteristics of the products, and substantially increases the crystallization rate, which improves the life of dies. The results of mathematical modeling underlie the selection of thermomechanical conditions for forging of metals (iron, steel, and aluminum alloys) that crystallize under pressure. A number of liquid metal forging processes are mastered. [ABSTRACT FROM AUTHOR]

The thermoplastic characteristics of high-manganese steels with different phosphorus and sulfur contents were investigated. The zero-ductility temperature and plasticity-temperature range of the high-manganese steels were reduced significantly with increase in phosphorus or sulfur content. The relationship between the initial forging temperature of the high-manganese steel and the content of phosphorus and sulfur can be expressed as Tift = 1200 - 1530wS - 1650wP. The final forging temperature is 900°C, and the heating rate during the forging of the high-manganese steel crossing must be slow. The lifetime of the forged high-manganese steel crossing was almost doubled compared with conventional cast high-manganese steel crossing. [ABSTRACT FROM AUTHOR]

Results are provided for a study of the distribution and location of nonmetallic inclusions in large forgings of steel 38KhN3MFA weighing 24.2 and 23.52 tons with a normal configuration and with a changed shape of the bottom part (“convex” bottom) cast in a vacuum. It is shown that the change in ingot bottom section geometry leads to an increase in temperature gradient and as a consequence to an increase solid phase advance intensity. In turn, this leads to more uniform distribution of oxysulfide inclusions. The sulfide inclusion content in the ingots compared increases from the periphery to the ingot axis. Dependences are obtained for metal ductility properties, i.e., relative elongation, relative reduction of area, and impact strength on sulfide inclusions distribution over ingot levels, and their unfavorable effect on these properties is established. It is shown that a reason for the reduction in ductility properties is sulfide phase location in the form of films of dendrite boundaries that occurs under conditions of a shortage of oxygen in the melt. This leads to a reduction in oxysulfide content and formation of a sulfide component in an unfavorable form distributed over cast grain boundaries. The ingots are destined for domestic power generation engineering forgings. [ABSTRACT FROM AUTHOR]

A criterion is suggested for evaluating steel tendency to forming chemical inhomogeneity based on calculating distribution coefficients and accommodation of elements in steel composition. It is shown that the criterion proposed correlates with carbon liquation coefficients through the cross section of forging ingots of different weight (0.5-650 tons): with an increase in the value of the suggested criterion there is an increase in carbon liquation, and consequently chemical composition inhomogeneity. The use of this criterion in developing steel composition for new grades will make it possible to reduce their inclination for forming chemical inhomogeneity providing greater metal product property stability. [ABSTRACT FROM AUTHOR]

A technology of producing hollow railroad axles by screw piercing and radial forging is developed. The design of hollow axles and the production technology are described. The sequence of piercing and forging operations is presented. Trial rough axles were produced. Their mechanical properties are tested, and the test results are compared to the requirements to solid axles. [ABSTRACT FROM AUTHOR]

The effect of molybdenum in an amount of 0.15% on the microstructure and properties of low-alloy pipe steel plate prepared by controlled rolling technology with accelerated cooling is studied. A favorable effect is established for molybdenum on increasing strength properties and sheet hydrogen induced cracking resistance. [ABSTRACT FROM AUTHOR]

Surface defects of special alloy steel round bar of different grades, reasons for their occurrence and degree of influence with a change in microstructure on the capacity for cold upsetting according to groups 66 and 66T by GOST 10702-78 are studied. It is established that necessary conditions for obtaining positive test results for cold upsetting are simultaneous preparation of a favorable granular pearlite microstructure and the absence of round bar surface defects more than 100 μm deep. The absence of surface defects with an unfavorable microstructure does not guarantee positive test results. [ABSTRACT FROM AUTHOR]

Comparison of mathematical modeling data with results of studying ingot structure show that a higher temperature in a narrow axial part of an actual ingot slows down solidification. This leads to an increase in dendrite parameter, a reduction in dendrite structure density, an increase in porosity, an increase in the amount of readily-melting sulfide and nonmetallic inclusions, and the formation of secondary shrinkage cavities. This location of shrinkage and liquation defects facilitates their removal during ingot forging and makes it possible to prepare hollow forgings from them. There is a fourfold reduction in chemical inhomogeneity and an increase in mechanical property stability over the length in test ingots. Use of lengthened double ingots for preparing hollow ingots makes it possible to increase satisfactory metal output in a forging by 8%. [ABSTRACT FROM AUTHOR]

This article discusses research done on modeling, analyzing, and optimizing the technology used to forge the titanium sections of pressure vessels. The finite-element method was used for computer modeling of the deformation of the material during the forging operation. The study examined the forging force, the uniformity of deformation of the vessel's walls, the filling of the dies, and the probability of crimping. Consideration was given to the possibility of using the phenomenon of superplasticity to forge the given product. The superplastic flow regime is maintained only during the final stage of the forging operation (the last 20% of the stroke of the die) in order to shorten operation as a whole. This is done by setting the die speed at a value which ensures that the material is deformed within a prescribed rate range and that the limits specified for the maximum forces are observed. Several alternatives were examined for making the vessel, these variants differing in the form of the semifinished product and the configuration of the dies. With constraints on the maximum loads and forging time, the technology that was chosen makes it possible to significantly increase the coefficient that characterizes the utilization of titanium in the production process. [ABSTRACT FROM AUTHOR]

Results are provided for a study of features of the structure of extended double hot-topped ingots. In the upper half of a test ingot, there is significant development of defects of shrinkage origin (closed secondary shrinkage cavities and zone of axial porosity), and they are significantly developed over the height and insignificantly over the diameter. Defects of shrinkage origin are concentrated within the upper half of an ingot body. It is established that within a double ingot nonmetallic inclusion distribution and cast structure parameters differ from the distribution for an ingot of normal geometry. Comparison of mathematical modeling data with results of studying ingot structure shows that a higher temperature in a narrow axial part of an actual ingot slows down solidification. This leads to an increase in dendrite parameter, a reduction in dendrite structure density, an increase in porosity, the amount of readily melting sulfide and complex oxysulfide nonmetallic inclusions, and also formation of a closed secondary shrinkage cavities. This position of defects of shrinkage and liquation origin facilitates their removal during ingot forging, and provides the possibility of obtaining hollow forgings from them. In test ingot forgings, there is a fourfold reduction in their chemical inhomogeneity and an increase in mechanical property stability over an object's length. Use of extended double ingots for preparing hollow billets makes it possible to increase output of finished metal in a forging by 8%. [ABSTRACT FROM AUTHOR]

Results are presented from the use of numerical modeling to perform an empirical assessment of the effect of the initial process parameters in hot die forging (the temperatures to which the deforming tools and semifinished product are heated) on the temperature field in the semifinished product during deformation. A series of numerical experiments is performed on the basis of the finite-elements method, the resulting data are analyzed, and relationships between the parameters are established and explained. [ABSTRACT FROM AUTHOR]

Data on the production of blanks for gas-turbine engines and power units in the 200 MN die-forging press at the Electrostal Metallurgical Plant are presented. The range of geometries and grades of blanks produced in the 200 MN press is described. [ABSTRACT FROM AUTHOR]

The effect of volume factor on the microstructure of forgings produced by developed technology is considered. The identical nature is established for microstructure of forgings 100 and 250 mm thick. The level of β-phase dispersion is determined. It is shown that presence of different structural components has a favorable effect on alloy mechanical properties and operating capacity indices. Microstructure parameters are determined facilitating an improvement in level of crack resistance. [ABSTRACT FROM AUTHOR]

Examples are presented of using computer simulation for evaluating the effect of production parameters on billets' quality properties and development based upon this of rational production regimes. Criteria evaluated during simulation for solidification and forging criteria are described. The possibility is considered of using results obtained during simulation of solidification as starting data in modeling forging processes. [ABSTRACT FROM AUTHOR]

This article examines questions related to improving the quality of hot-worked bimetallic powder materials. It analyzes the technological factors in the first stage of the process of producing a bimetal - cold pressing of the outer layer. A description is given of a technology that eliminates the need for auxiliary structural elements for the compression mold (shells, connectors, etc.), better protects the preform from oxidation while it is being heated prior to finish forging, and improves the quality of the transition layer and the bimetal as a whole. [ABSTRACT FROM AUTHOR]

Certain general trends in the radial and axial distribution of segregates in forging ingots are identified based on computer modeling and a generalization of data from studies of chemical heterogeneity in such ingots. Recommendations are developed on optimizing the geometry of forging ingots to minimize this heterogeneity. [ABSTRACT FROM AUTHOR]

The Bakor Scientific-Technical Center has developed a new material with a corundum-mullite-zirconium composition to line the bottom of pusher heating furnaces. The material owes its high strength to the use of high-tech raw materials and a modified binder. Positive results have been obtained from the use of preshaped blocks in a continuous furnace at a forging-machine plant (in Ukraine). [ABSTRACT FROM AUTHOR]

The crystallization of a steel ingot is physically modeled to determine features of its solidification and the growth of shrinkage defects. The modeling is done using ingots with a standard hot top and ingots with a chilled top. The results obtained in the modeling were substantiated by a study of the cast structure of actual ingots. The character of the development of carbon, sulfur, and phosphorus segregation over the cross section of ingots is determined along with the location and size of shrinkage defects in ingots cast with tops having different thermal properties. Results are presented from a study of the quality of the metal of tubular forgings obtained from experimental and control ingots. [ABSTRACT FROM AUTHOR]

The technologies that are used to make hollow ingots are analyzed. Their characteristic features are discussed along with their intrinsic advantages and disadvantages. A new technology that significantly alleviates the formation of defective regions in hollow ingots during their crystallization is proposed. [ABSTRACT FROM AUTHOR]

Results are presented from physical modeling of the crystallization of killed-steel ingots. The article also describes structural features of the axial zone of industrial ingots cast in molds with a reconfigured bottom and explains the mechanism by which defects form in this zone. [ABSTRACT FROM AUTHOR]

This is the third and final article on a method developed by TsNIITMASh to design forging ingots so as to prevent the formation of an axial shrinkage cavity in the body of the ingot. Theoretical and experimental results from use of the method and factory-designed casting equipment to obtain such ingots are compared together with requirements of the standard OST 108.962.02-85. It is shown that the theoretical and experimental results agree satisfactorily with one another . [ABSTRACT FROM AUTHOR]

With the aim of excluding defects and scrap during manufacture of disk and plate forgings of steel EP742-ID at the Chelyabinsk Metallurgical Combine work is carried out for studying alloy microstructure (including use of electron diffraction studies) for determining process ductility and the effect of microalloying on alloy process ductility. A connection is established between alloy process ductility and microalloying addition (cerium and lanthanum) content, and their optimum content in starting metal is determined. [ABSTRACT FROM AUTHOR]

The main capabilities of software developed by the ESI Group to model welding is briefly reviewed. The article describes the principal data needed to formulate a welding problem and presents results that a user of the software can obtain after performing the calculations. [ABSTRACT FROM AUTHOR]

Results are presented from a determination of how the geometric characteristics and location of nonaxial segregation strings in large ingots are affected by the change in the shape of the ingots' bottom part when they are cast in molds with a convex bottom plate. Refined data are obtained on the boundaries of regions affected by such segregation in the reconfigured ingots and in ingots having the normal geometry. [ABSTRACT FROM AUTHOR]

The advantages and disadvantages of different types of shaping operations (extrusion, forging, combination variants) for sintered semifinished products of powder molybdenum alloys are examined. The article presents the mechanical properties and microstructure of bars of cast and powder molybdenum alloys obtained from semifinished products deformed by different methods. [ABSTRACT FROM AUTHOR]

The use of superplastic regimes in drop forging, the shaping of flat-rolled semifinished products, and various special processes that have been developed for metal-shaping is making it possible to expand the capabilities of these operations by unprecedented amounts while reducing energy consumption in the shaping operation, saving significant quantities of metal, decreasing the volume and labor-intensiveness of the machining operations that are required, and improving the quality of the finished product. As examples, the article examines the superplastic forming of shells from flat-rolled products, the fabrication of cellular structures by superplastic forming combined with diffusion welding (SPF-DW), the formation of ribbed shells on thermoelastic presses, and the drop forging of large thin-walled panels on hydraulic presses in the superplastic regime. [ABSTRACT FROM AUTHOR]

A method is proposed for determining the residual ductility of the material of a semifinished product. The method makes it possible to forge bars on a radial forging machine with the use of technically sound regimes for the reduction of semifinished products. The investigation that was performed involved both theoretical and experimental research. The theoretical part included determination of the stress state in the deformation zone in accordance with a new mathematical model, determination of the shear strain and ductility of the metal, and evaluation of its residual ductility in the forging of bars on a radial forging machine. In addition, an experiment was performed which involved the multi-pass forging of bars of different alloys with different reductions in each pass. The adequacy of the model was checked by comparing the calculated data with the experimental results obtained by forging bars made of different alloys. [ABSTRACT FROM AUTHOR]

This article examines the choice of the computer program DEFORM for finite-element analysis of transients in metal-shaping operations (MSO). The possibilities of the program for solving nonsteady problems that are fairly difficult to model are explored by using two different MSO as an example – forging on an AVS radial-forging machine with complex motion of the tool and the rolling of strip with the formation of fins on one side. The results of the solution are analyzed using the DEFORM post-processor. The availability of experimental data on the rolling of unilaterally finned strip and the forging of bars on AVS machines made it possible to evaluate the accuracy of the theoretical results. It is concluded that use of the DEFORM program is effective for studying transients in MSO. The data obtained in the process make it possible to design new and improve existing technologies and machines for shaping metals. [ABSTRACT FROM AUTHOR]

Results are presented from a study of the macrostructure, chemical nonuniformity, and mechanical characteristics along and across propeller shafts made from 39.5-ton ingots. The optimum parameters for casting large forging ingots are determined, these ingots serving as the semifinished product for obtaining finished products used in machine construction. The uniformity of the carbon distribution in the ingots and the forgings is maximized so as to minimize variations in the mechanical characteristics along and across the finished products. [ABSTRACT FROM AUTHOR]

This article examines questions related to the development of a technology for producing large ingots of good quality. It identifies problems encountered in obtaining quality metal in large ingots and forgings within the context of advanced metallurgical methods and equipment now being used to treat steel outside the furnace. An evaluation is made of technological measures developed to improve the mechanical characteristics and special properties of products obtained from large forgings. [ABSTRACT FROM AUTHOR]

This article examines the problem of constructing a mathematical model to describe the process of deformation carried out on an AVS radial forging machine to prepare the ends of tubes for further processing. The model makes it possible to determine the energy-force parameters of the reduction process – the most important factors for drawing up production schedules and choosing the composition and design of the equipment. A computational program is created to determine the reducing forces in tubes and bars. The program accounts for strain-hardening and makes it possible to determine the extent to which the ductility of the tube material is used. It also allows variation of the parameters of the forging operation, including the angle of the die, the friction index, the front and rear thrust of the semifinished product, and the feed. Experiments involving the shaping of different types of semifinished products on an AVS radial forging machine fully substantiate the accuracy of the mathematical model. [ABSTRACT FROM AUTHOR]

This article discusses the use of information technologies in modeling technologies for shaping metals. Design techniques are illustrated by using the multi-functional computational complex SPLEN as an example. Methods that have been developed to analyze the operations involved in drop forging and rolling are now being successfully used at several machine plants. [ABSTRACT FROM AUTHOR]

In order to study the behavior of surface cracks in the initial roughing stands of a wide-strip hot-rolling mill, a special laboratory study was performed in order to determine the subsequent effect of the cracks on the quality of the rolled product. This was done using lead samples serving as analogs for the continuouscast blanks. The results obtained supported qualitative and quantitative determination of the primary laws governing changes in the shape of blanks during rough milling. [ABSTRACT FROM AUTHOR]

A method has been proposed for classifying internal defects in forgings based on the flaw-detection patterns obtained in ultrasonic testing. The reliability of the method is greater than 75%. Also, a program has been developed to classify internal defects in relation to their length and their location through the thickness and width of forgings. The method is valid for flaw-detection patterns in groups I and III. The method is now being used at the Chelyabinsk affiliate of the Ural Forging Company. The method of classification can also be used to identify internal defects in cylindrical specimens obtained by free forging on presses. [ABSTRACT FROM AUTHOR]

The proposed measurement method and the structure of the recommended measurement system offer a wide range of possibilities for completing all the operations that need to be performed with the signals received in the system. The signals and their extrema are digitally analyzed and recorded with the computer’s processor and are subjected to arithmetic and logic operations, differentiation, integration, etc. The proposed measurement system was installed on universal mill PVP 20-60 (VILS) and has been used to roll bars made of hypereutectoid aos and pierce them into shells. The given measurement method makes it possible to perform a whole range of measurements and calculations of energy-force characteristics and other process parameters that collectively can satisfactorily describe the operation of helical rolling. [ABSTRACT FROM AUTHOR]

This article examines the issue of reducing noise and vibration in forging shops. Results are presented from studies organized to develop designs of vibration-proofing devices for hammers in these shops’ since such hammers are the main vibrationally active equipment in the shops. Durable and highly efficient sound suppressors have been designed to alleviate aerodynamic noise from the most active sources — the air distributors of the control systems of presses in forging shops. Recommendations are given on use of the proposed measures in these facilities. [ABSTRACT FROM AUTHOR]