Investigation of the stress-strain state and microstructure transformation of copper busbars in the deformation zone during continuous extrusion

2021 ◽  
Vol 1 (1) ◽  
pp. 36-48
Author(s):  
A. N. Koshmin ◽  
A. V. Zinoviev ◽  
A. Ya. Chasnikov ◽  
G. N. Grachev
Keyword(s):  
Grain Size ◽  
Plastic Strain ◽  
Deformation Zone ◽  
Strain State ◽  
Stress Strain ◽  
Deformation Heating ◽  
Stress Strain State ◽  
The Press ◽  
Metal Deformation ◽  
Continuous Extrusion

The paper describes an extensive study of features peculiar to physical and mechanical processes occurring in metal in the deformation zone during the continuous extrusion of Cu-ETP rectangular busbars 10×60 mm in size. Finite element computer simulation was used to obtain the values of extrusion power parameters. It was noted that moment and force values increase to the point of filling the press chamber free space with metal reaching a maximum of 12.26 kN·m and 1.54 MN, respectively. The stress-strain state analysis of metal in the deformation zone made it possible to obtain distribution fields of accumulated plastic strain, strain rate intensity and average stresses, and to build the graph of metal temperature variation over time during extrusion. Maximum levels of accumulated plastic strain and compressive stresses are observed in the contact zone of the workpiece with the press container abutment. The most intense metal deformation heating also occurs there. The comparison of modeling and microstructural study results indicate that a significant portion of the cast structure grinding work occurs at the entrance to the deformation zone and at the abutment zone subjected to the highest level of compression stresses. Metal deformation during the die passage leads to an oriented crystal structure formed with a grain size of 25–30 μm. Sample hardness measurement results are consistent with the results of structure analysis in the studied areas of the deformation zone. When the workpiece passes through the compression container abutment section, deformation heating occurs, which leads to a decrease in hardness from 93 to 67 HV. After the metal passes through the die, recrystallization processes continue in it leading to a slight increase in grain size and, accordingly, a decrease in hardness from 79 to 74 HV, which continues until the busbar contacts a cooling medium.

scholarly journals Studying the effect of elastic-plastic strain and hydrogen sulphide on the magnetic behaviour of pipe steels as applied to their testing

2018 ◽  
Vol 145 ◽  
pp. 05003
Author(s):  
Anna Povolotskaya ◽  
Eduard Gorkunov ◽  
Sergey Zadvorkin ◽  
Igor Veselov
Keyword(s):  
Plastic Strain ◽  
Initial Stress ◽  
Elastic Deformation ◽  
Hydrogen Sulphide ◽  
Strain State ◽  
Pipe Steel ◽  
Magnetic Behaviour ◽  
Pipe Steels ◽  
Stress Strain ◽  
Stress Strain State

The paper reports results of magnetic measurements made on samples of the 12GB pipe steel (strength group X42SS) designed for producing pipes to be used in media with high hydrogen sulphide content, both in the initial state and after exposure to hydrogen sulphide, for 96, 192 and 384 hours under uniaxial elastic-plastic tension. At the stage of elastic deformation there is a unique correlation between the coercive force measured on a minor hysteresis loop in weak fields and tensile stress, which enables this parameter to be used for the evaluation of elastic stresses in pipes made of the 12 GB pipe steel under different conditions, including a hydrogen sulphide containing medium. The effect of the value of preliminary plastic strain, viewed as the initial stress-strain state, on the magnetic behaviour of X70 pipe steels under elastic tension and compression is studied. Plastic strain history affects the magnetic behaviour of the material during subsequent elastic deformation since plastic strain induces various residual stresses, and this necessitates taking into account the initial stress-strain state of products when developing magnetic techniques for the determination of their stress-strain parameters during operation.

scholarly journals Study of the Stress-Strain State of the Process of Drawing Wire from an Alloy of Palladium with Nickel

2020 ◽  
Vol 992 ◽  
pp. 504-510
Author(s):  
S. Sidelnikov ◽  
V. Lopatin ◽  
M. Dobrovenko ◽  
E. Lopatina ◽  
R. Sokolov
Keyword(s):  
Strain State ◽  
Current Mode ◽  
Wire Drawing ◽  
Stress Strain ◽  
Limit Values ◽  
Stress Strain State ◽  
Limit Value ◽  
Drawing Die ◽  
Metal Deformation ◽  
3D Software

This article present the results of studies of the process of wire drawing from the PdNi-5 alloy, performed using computer simulation in the DEFORM 3D software package. В качестве материала для исследований использовали сплав с содержанием 95% палладия и 5% никеля. An alloy with a content of 95% palladium and 5% nickel was a material for research. The patterns of changes in the stress-strain state for the current processing mode determined, and a more rational drawing mode with a redistribution of drawing coefficients along transitions proposed. For the proposed regime, using the created model, the values of drawing stresses, drawing forces and Cockcroft-Latham criterion determined. It was found that the stress distribution in the deformation zone corresponds to the generally accepted laws of their change, and their maximum values are realized in the metal located in the calibrating zone of the drawing die. In addition was revealed that the stresses in the current mode have limit values at the second and fourth passes. The redistribution of deformation indicators in the proposed mode allowed reduce the magnitude of these stresses and, thereby, reduce the likelihood of wire breaks. The maximum value of the Cockcroft-Latham criterion is achieved in the last transitions, but at the same time, destruction will not occur, since they do not exceed the limit value. The drawing force also decreases with the implementation of the proposed mode and does not exceed the permissible values regulated by the technical characteristics of the equipment. Since it is the proposed mode of wire drawing, it is characterized by a decrease in energy power indicators and the likelihood of wire breakage in the process of metal deformation it can be recommend it for implementation in existing production.

Research the process of cold punching of hex nut blanks of increased height

2019 ◽  
Vol 75 (8) ◽  
pp. 979-984
Author(s):  
I. G. Shubin ◽  
A. A. Kurkin ◽  
A. R. Bazykov ◽  
F. A. Stolyarov
Keyword(s):  
Strain State ◽  
Metal Flow ◽  
Geometrical Parameters ◽  
Stress Strain ◽  
Industrial Testing ◽  
Stress Strain State ◽  
Metal Deformation ◽  
3D Software ◽  
Through Hole ◽  
Power Costs

The high nuts withstand increased load for expansion, facilitating its even distribution along the bolt length. The process of increased height nut blanks plastic deformation characterized by uneven metal flow and changing of stressed state by the blank section. In the process of closed-die stamping of such nuts a risk of their geometry distortion arises. Results of study of the process of production a hex nut of increased height presented. The object of the research was to study the process of the metal deformation when broach a hole for thread in a hexagonal nut blank of increased height. To simulate the stress-strain state, the QForm-3D software package was chosen, which made it possible to predict with sufficient accuracy the metal flow in the blank, calculate the deformation forces and determine the stresses that occur in the tool. The models of the blank and the tool were created in the Compass 3D program without internal and external defects. When performing the work, the parameters of the stress-strain state of a hexagonal nut blank of increased height were calculated. The simulation results showed the need to change the geometry of the end part of the punch to a conical one with an angle of 150 degrees and a reduction in the size of the baffle height from 10.4 mm to 5.4 mm. The adopted changes allowed to reduce the energy and power costs of forming a through hole for the threads. Industrial testing confirmed the correctness of the calculations. Nuts with edges perpendicular to its base and the required geometrical parameters were obtained.

Strain and Friction Effect on the Stress-Strain State in the Deformation Zone during Cold Rolling of Thin Beryllium and Aluminum Foils

2019 ◽  
Vol 822 ◽  
pp. 716-724 ◽  
Author(s):  
Vasiliy V. Mishin ◽  
Ivan A. Shishov ◽  
Vladimir V. Paromov
Keyword(s):  
Friction Coefficient ◽  
Cold Rolling ◽  
Deformation Zone ◽  
Strain State ◽  
Hydrostatic Stress ◽  
Stress Triaxiality ◽  
Fracture Prevention ◽  
Stress Strain ◽  
Stress Strain State ◽  
Contact Arc

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).

scholarly journals Study of stress-strain state during cross-wedge rolling with one tool

2019 ◽  
Vol 64 (2) ◽  
pp. 175-181
Author(s):  
G. V. Kozhevnikova
Keyword(s):  
Computer Simulation ◽  
Comparative Studies ◽  
Deformation Zone ◽  
Strain State ◽  
Average Stress ◽  
Cross Wedge Rolling ◽  
Axial Region ◽  
Stress Strain ◽  
Cross Rolling ◽  
Stress Strain State

The peculiarity of cross-wedge rolling with one tool is the workpiece deformation with one tool and the fact that the workpiece is not supported with the tool from the opposite side. On both sides of the tool outside the contact with the workpiece, the workpiece is fixed with pairs of upper and lower tools, by means of which the axis of the workpiece is held in a constant position. Such conditions of rolling qualitatively change the deformation zone and, as a result, the stress-strain state.The change in the stress-strain state was qualitatively estimated by comparing the fields of slip lines in the traditional two-tools cross rolling and one-tool cross rolling. One-tool cross rolling increases the normal and average stress at the contact by 7.8–14.5 %, changes the average stress of the specimen from tensile to compressive one in the axial region. This circumstance significantly increases the resource of plasticity and allows rolling metals with limited plasticity without opening the axial cavity. Comparative studies of the stress-strain state from the traditional two-tools cross-wedge rolling and one-tool cross-wedge rolling in the axial region of the workpiece have been carried out by computer simulation.

scholarly journals DETERMINATION OF THE OPTIMAL SPEED OF THE MANDREL IN THE CONTINUOUS REELING MILL USING NUMERICAL SIMULATION

2017 ◽  
pp. 86-92 ◽  
Author(s):  
Yu. L. Bobarikin ◽  
Ya. I. Radkin
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Deformation Zone ◽  
Numerical Experiments ◽  
Strain State ◽  
Stress Strain ◽  
Optimal Speed ◽  
Stress Strain State

A proper numerical model of expanding process on a three roll continuous reeling mill was created and number of numerical experiments of the process of tubes rolling were performed. Based on the analysis of the stress-strain state of a rough tubes deformation zone, optimal speed rates of the mandrel providing the decrease in mill rolls and deterioration of mandrel which direct influences on the quality of rough tubes were determined. 

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