F. Z. Utyashev

Scientific fundamentals of high-efficiency roll forming technology for axially symmetrical parts of a gas-turbine engine rotor of high-temperature alloy

Fundamentals of the roll forming technology for disks of gas-turbine engines under super-plasticity conditions are stated. Because of deep underlying reasons of materials science, the technology provides a high process efficiency, equipment universality, the possibility of obtaining workpiece blanks with a high accuracy approaching that of the final part, and the development of structural states corresponding to the optimum complex of operational properties of parts [1, 2]. It is shown that a substantial role in roll-forming technology is played by superplastic deformation conditions, which, in contrast to the simple isothermal deformation, allow us to obtain in disks, either the homogeneous structure and isotropic properties, or the regulated gradient structure corresponding to actual temperature-force conditions of the operation of different parts of gas-turbine rotor disks.

Strain Compatibility and Nanostructuring of Bulk Metallic Materials via Severe Plastic Deformation

Nanostructured (NS) metallic materials can exhibit high strength at room temperature and superplastic properties at elevated temperatures. This enables to enhance their technological and structural properties, when producing various parts from them. For producing NS materials by severe plastic deformation (SPD), the development of effective SPD techniques for practical use is an urgent task. It is shown that solution of such a task should take into account strain compatibility on the macro-, meso- and micro-levels. Not only shear but also rotational deformation mode should be considered. Properties of NS materials and possibilities of their structural applications are considered from this point of view.

New Technologies Development and Equipment for Local Shape-Forming of the Complicated Parts Made of Heat-Resistant Alloys under Superplastic Deformation Conditions

The results of development of new resource-saving technologies of local shape-forming under superplastic deformation conditions (SP) by means of roll-forming and rotary swaging are presented. These technologies are efficient for fabrication of discs, shells, rings up to 800 mm in diameter, as well as hollow shafts made of heat-resistant nickel-, titanium-and iron-based alloys that are used in aircraft engines and ground power installations. In particular, to implement innovative technologies a universal SRZhD-800 roll-forming mill has been developed for discs roll-forming made of heat-resistant alloys under SP. An efficiency of using of semi-finished products with prepared ultrafine grained (UFG) structure for generating precise complex geometry profile parts both homogeneous and regulated structure that changing in the radial direction of the disc and for obtaining high mechanical properties that are optimized taking operational conditions into account is proved. The technological process of rotary swaging under SP conditions has been developed for fabrication parts made of high alloy heat-resistant alloys using demountable mandrels. This method allows to obtain precise complex geometry profile parts such as disc with a thin cone flange which is characterized by homogeneous structure and high mechanical properties.

Specific features of rolling of shaft of gas turbine engine under conditions of superplasticity

This work is devoted to the specific features of the rolling of hollow shafts made of nickel-base superalloys under conditions of superplasticity. Limitations are mentioned, which hamper the use of the highly efficient multiroller rolling of the shafts made of these alloys under conditions of superplasticity. The tried and tested procedure of rolling hollow shafts, which involves the use of a mandrel and a single roller, is presented. It is shown that the shaping of a shaft using this procedure requires an expanded bulk deformation zone to appear, which propagates over the entire cross section of the blank under the zone of its contact with the roller. The dimensions of the tool that provide the formation of this deformation zone are determined. The possibility of the use of the axisymmetric formulation of the problem on bulk deformation in the course of the rolling of shafts to determine the stress-strain state of the material is substantiated with the help of the Deform-3D applied software package.

Modeling the structure formation during hot deforming the billets of the parts of gas-turbine engines made of heat-resistant nickel alloy

The results of finite-element and physical modeling of deformation heating and structure formation during high-temperature isothermal upset of a cylindrical billet according to various modes (continuous and fractional deformation) have been presented. The results of numerical modeling, which agree with the experimental modeling data, showed that, in order to minimize the deformation heating and formation of a homogeneous ultrafine-grain structure in bulk billets made of heat-resistant alloys, it is purposeful to perform the deformation fractionally (with a single degree no larger than 30–50%), which allows for the deformation rate and performance of post-deformation annealing. The formation of an ultrafine-grain structure in the billets made of nickel alloys (for example, EP742U) guarantees an increase in the quality of ready wares.

Technological features of a process and equipment for superplastic rolling of axially symmetric heat-resistant alloy components of rotors for modern aircraft engines

Scientific bases of a technology for superplastic roll forming of axially symmetric parts of gas turbine engines that are made of heat-resistant alloys are described. It is shown that a formed microcrystal structure allows their deformation under conditions of superplasticity, thereby providing changes in physical and mechanical and processing properties. Parts manufactured by superplastic rolling feature a highly homogeneous microstructure over the entire volume and isotropic mechanical properties or an optimized gradient microstructure allowing for nonuniform temperature and power loading in the process of operation. Technological features of the equipment for superplastic roll forming of discs for motors and requirements for the equipment and the control system are described and methods of calculation of major unit strength are covered.

Manufacturing of Axisymmetric Components out of Superalloys and Hard-to-Deform Steels by Roll Forming

Heat-resistant alloys are the basic material of gas turbine engine (GTE) design. Fine-grained structure in these alloys can be formed by isothermal forging and then different axisymmetric GTE components as wheels, shafts, rings can be superplastic roll formed. Examples of the superplastic and isothermal deformation use for manufacturing components out of superalloys and steels for critical applications are given. The possibility of roll forming parts as rings with a diameter up to 800 mm and as flange - cone with a diameter up to 600 mm out of superalloys (Inconel 718, EK79, EP741NP), accordingly, on SRZHD-800 and modified PNC-600 mills were showed. The macrostructure investigations of the components after the roll forming showed that the homogeneous structure was formed. The microstructure at the flange portion was fine-grained and at membrane zone was coarse-grained. Cone part was roll formed at isothermal condition from pre-stamped chromium martensitic steel sheet. Manufacturing technology of roll forming was tested by computer and physical simulation. Service properties of components were obtained by subsequent heat treatment. The effectiveness of the technology associated with increased service properties of components and decreases the labor content by automated equipment.

Deformation Nanostructuring and Superplastic Processing of Metallic Materials

Theoretical and practical aspects of fabrication and processing of bulk metallic nanomaterials are presented. The effect of different deformation modes on the structure formation is shown. Development of nanotechnology with respect to fabrication of gas turbine engines (GTE) parts made of nanostructured superalloys is exemplified.

Superplastic Behavior of ATI 718Plus Superalloy

Complex shaped, ultra thin-walled parts can be manufactured using superplastic forming. Hot working temperature for the production of fine-grained billets (d=5-15 μm) out of ATI Allvac 718Plus® superalloy is in the range of 982-1038°C. An ultrafine-grained structure (d=0.3 μm) was produced by multi-axial forging with a gradual decrease of the forging temperature from 950 to 700°C. Superplastic properties of the alloy were carried out in the temperature interval of 700-950°C. It has been revealed that the fine-grained alloy provided superplastic elongations about 300% at 950°C and strain rate of 10-4 s-1. The highest elongation of ultrafine-grained alloy was about 1450% and very low flow stresses were reached at 900°C and strain rate of 3×10-4 s-1. The ultrafine-grained alloy showed superplastic properties also at 700°C (0.62Tm). The microstructure and superplastic properties of the alloys 718 and 718Plus are compared.

Physical and numerical modeling of the process of rolling off of a tapered shaft of aviation purpose

One of the most promising methods of manufacturing axisymmetric parts of gas turbine engines is local deformation on specialized rolling mills. To design this class of manufacturing operations and equipment, it is effective to use physical and numerical modeling. The article has provided the method and results of physical and numerical finite-element modeling of local deformation process of a detail of a cone-with-cylinder type made of EI962–Sh chromium steel. Analyses of the energy-power parameters of the technical process and the possibility of the destruction of a part during the deformation process have been carried out.