Papers by Keyword: Deformation Zone

Abstract: The metal workpiece Surface Layer (SL) Residual Stresses (RS) modeling and computational algorithms creation relevance is shown. The RS forming discrete elastoplastic finite element model at Surface Plastic Deformation (SPD) hardening treatment, including technological inheritance effect, is presented. A model feature is the complex non-monotonic types of metal loading and subsequent unloading and hardened body effect consideration, as well as residual stress tensor components evaluation as a result of these effects. Residual stress tensor components calculations in the workpiece hardened surface layer after treatment with different routines are performed. The metal hardening effect on the residual stresses values and distribution is established. The correlations between the residual stress tensor components and the main treatment routine parameters - the roller tension and profile radius are established.

Abstract: The effect of strain and the friction on the stress-strain state in the deformation zone during cold rolling of thin beryllium and aluminum foils was investigated in this work. Calculations showed that material hardening has a significant influence on the contact pressure distribution along the contact arc. Although it, the distributions of hydrostatic stress and stress triaxiality are favorable for fracture prevention both beryllium and aluminum except narrow regions near the entrance and the exit of deformation zone for all considered cases (strain up to 40%, friction coefficient in range 0.03 – 0.3). The most favorable stress state is observed during cold rolling with a high friction coefficient (rolling without lubrication).

Abstract: The process of continuous extrusion Conform, relating to modern energy-efficient metalworking technologies, is now widespread in the production of hollow and solid long-cut profiles of various cross-sections made of aluminum and copper alloys. However, in questions relating to the metal flow pattern and the formation of microstructure and mechanical properties, directly at the deformation zone, it has not studied sufficiently [1]. The work aimed at studying the nature of the metal flow and the transformation of the microstructure and mechanical properties of the copper alloy GOST-M1 (DIN-ECu-57) in the deformation zone during the pressing of round (Ø 8, 24, 30 mm) and flat (10 × 30, 10 × 60, 10 × 80, 10 × 100 mm) profiles. It was performed on the basis of New Metallurgical Technologies Ltd. and the department of metal forming of the NUST MISiS. In the pressing process, the templates of these profiles were selected, further samples for experiment were made and the study of the nature of the alloy flow in the longitudinal direction were carried out (continuous casting - deformation center - finished profile).

Abstract: The provision of certain information regarding the surface layer of the equipment parts is one of the critical issues for the modern mechanical engineering. The development of new technologies of protective-strengthening treatment of critical parts surface requires the development of improved methods for surface layer material state assessment as a result of high-energy impact typical for ion-plasmatic, ion-implantation and combined treatment method. Moreover, the peculiarities of industrial mechanical engineering production require the development of simple and efficient methods of surface layer parameters checkout. The application of protective coatings complicates the use of universal method of the parts surface layer parameters assessment. The present article is devoted to the development and studying of a new method for the parts surface layer state assessment after its treatment of various types, including the protective-strengthening technologies and the application of protective coatings. The specific features of the proposed assessment method are its simplicity, reliability, and universality.

Abstract: Intensive development of Russian aviation and aerospace industries put an emphasis to the problem of quality of using materials and workpieces and to the value of technical and economical indexes in the context of planned production level [1, 2]. Waste-free technologies are preferred. Cutting by torsion or cutting by shear are preferable technologies if thin-walled tube cutting is the main blanking operation. Build-up of workpiece deformation zone plays an important role in the cutting process. Deformation zone determines stability of details during further processing and exploitation. An extended research was conducted about tube separation process using torsion with an active counterpressure. Some parameters was defined in the result of research, in particular: distribution of deformation zone along length and thickness of workpiece, angular deflection and compression force and workpiece heating temperature impact on build-up of whisker disposition in the cut zone. It allows identifying optimum compression force range and temperature conditions. Compliance with recommended practices allows conducting thin-walled tube separation simultaneously with build-up on the workpieces whisker structure that is fortunate for further pressure treatment and exploitation.

Abstract: With the development of the contemporary industry, a need arises in the production of high - strength steels that can withstand heavy loads and work in harsh conditions. Industrial equipment (in particular, a hot-rolling mill) is subject to high loads that are close to critical. Therefore, the issues related to the development and applications of methods aimed at reducing of energy consumption during rolling are being solved before the product output. One of the efficient ways to reduce energy-power parameters of the process is the use of the rolling lubrication feed systems (RLFS) in the production of hot-rolled products. Accordingly, it is necessary to consider the method of supplying lubricating material (LM), its quantity, shared contact surfaces nature. Currently, one of the significant drawbacks in the RLFS is the lack of correlation between the quantity of fed LM and properties of the rolled material. As a result, RLFS are used in a restricted mode, and power consumption reduction is not significant: 3-6%.

Abstract: The paper considers issues of a mathematical model development of a “deformation zone - main electric drive” concerning hot plate mills. The dependence of the calculation of rolling torque on features of high deformation zone is given. Based on the obtained expressions, the structural diagram of the deformation zone model has been developed. The paper specifies the structure of the mathematical model for electric drive speed control system based on the known equations of synchronous motor. After the comparison of the transient processes of the electric drive coordinates and rolling settings obtained at the modeling and oscillography at the mill the conformity of the developed model to the studied object has been proved. The provided mathematical model is recommended to analyze the dynamic percussion leads that occurred at hot plate mill. The model obtained allows it to improve the reliability of the electromechanical system owing to the adaptation of the rolling schedule at the real-time operation mode.

Abstract: The dislocation theory is applied to study plastic deformation in high-speed cutting to show the formation characteristics of the micro scale deformation zone in high-speed cutting. Through the quick stoppage experiment of aluminum alloy 7050-T7451 in high-speed cutting and the further research of inclined cutting chip formation mechanism and deformation of shear zone in plastic mechanics and dislocation theory respect .The stress, the strain state and microstructure near the front edge of the rake face edge is analyzed. Effective flow stress, effective strain distribution and variation in shear deformation zone is simulated. According to the experimental and simulation results and from the microscopic respect, the traditional cutting deformation zone is reclassified, the deformation zone of the front edge and dislocations compression zone is increased to achieve a more accurate description of the deformation zone and provide a theoretical basis for the study of high-speed cutting deformation mechanism.

Abstract: Applying the research result of the whole corrugated web H-beam to rail structure, a new kind of rail structure, the corrugated web rail was generated. The special structure rail was successfully rolled in the Research Mill Institute of Yanshan University. This experiment proved that rolling force of corrugated web rail was greater. Based on the software ANSYS/LS-DYNY, the rolling process of corrugated web rail is simulated. Comparing with rolling traditional rail, nip condition, deformation zone, elongation modulus, zone of slippage on the delivery side and on the entry side of rolling corrugated web rail are analyzed, Through the analysis of the character of rolling corrugated web rail, the reason of greater rolling force is found out.

Abstract: In order to study the details of deformation and microstructures evolution during rolling and annealing process, magnesium alloy AZ31 blank, cast by unidirectional solidification and then sliced, has been rolled at high temperature with one pass deduction of 50% in a 2-high mill. During the rolling process, the mill was stopped, and the rolled sheet was rapidly cooled by the cold rolls. Samples with full length of rolling bite zone were cut form the semi-rolled sheet. Because twinning deformation can be reserved even the sample was polished and etched. The continuous changes of microstructure, from entrance to exit of roll bite, both rolled and annealed samples, were evaluated by Optical Microscope (OM), Scanning Electron Microscope (SEM). The results revealed that grain refinement mechanism was twinning intersection which segmented large grains into small pieces. The average grain size is 7µm after one pass 50% reduction hot rolling and 350°C, 15min annealing.