cold plastic deformation
Recently Published Documents


TOTAL DOCUMENTS

146
(FIVE YEARS 46)

H-INDEX

11
(FIVE YEARS 2)

2022 ◽  
Vol 960 (1) ◽  
pp. 012023
Author(s):  
D I Poiană ◽  
I Ionel ◽  
G Drăghici

Abstract When perforation by cold plastic deformation processes of long round pipes, the technological problems appear primarily at the deformation of the part section, in the perforation area by losing the stability of the part, in the case of holes made at a distance from the pipe ends. The purpose of the research was to determine the influence of the constructive shape of the pipe clamping devices in the perforation area, in order to determine the device that offers the best stability of the section, to allow obtaining possible holes as large in diameter. The research was based on the application of materials strength methods and the Castigliano method of solving the indeterminacy, related to the process of cold plastic deformation. The research materialized by determining some calculation relations and specific diagrams regarding the diameter’s variation of the perforated holes in the air environment, depending on the dimensions of the part and the mechanical characteristics of the part material, for different forms of clamping devices. The calculations were performed considering that the perforation is performed in air, with a punch applied from the outside of the considered piece. The calculation relations and the obtained diagrams allow the determination of the maximum orifices, for certain dimensions of the pipes and for different mechanical characteristics of the part material. At the conclusions, a comparison was made of the results obtained for the variants of clamping considered devices and the optimal shape of the device was established, which allows the making of the largest perforated holes in the part.


Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7393
Author(s):  
Ruslan Mendagaliyev ◽  
Oleg Zotov ◽  
Rudolf Korsmik ◽  
Grigoriy Zadykyan ◽  
Nadezhda Lebedeva ◽  
...  

The study of the formation of microstructural features of low-alloy bainite-martensitic steel 09CrNi2MoCu are of particular interest in additive technologies. In this paper, we present a study of cold-rolled samples after direct laser deposition (DLD). We investigated deposited samples after cold plastic deformation with different degrees of deformation compression (50, 60 and 70%) of samples from steel 09CrNi2MoCu. The microstructure and mechanical properties of samples in the initial state and after heat treatment (HT) were analyzed and compared with the samples obtained after cold rolling. The effect on static tensile strength and impact toughness at −40 °C in the initial state and after cold rolling was investigated. The mechanical properties and characteristics of fracture in different directions were determined. Optimal modes and the degree of cold rolling deformation compression required to obtain balanced mechanical properties of samples obtained by additive method were determined. The influence of structural components and martensitic-austenitic phase on the microhardness and mechanical properties of the obtained samples was determined.


2021 ◽  
pp. 57-63
Author(s):  
V.S. Vakhrusheva ◽  
V.M. Volchuk ◽  
N.V. Hruzin ◽  
I.A. Tiutieriev

A possibility was considered concerning estimation of grain anisomery in the structure of fuel cladding tubes of corrosion-resistant 026Cr16Ni15Mo3Nb steel of austenitic class rolled according to two flow charts: regular and intensive technologies using fractal formalism. Role of grain boundary hardening during cold plastic deformation was analyzed by studying the effect of the fractal dimension of grains D and their boundaries Dg on 0.2, w, and 5. The best correlation among those that were considered was observed between relative elongation and fractal dimensions of the grain structure (R2 = 0.90). The smallest correlation was observed with the yield stress (R2 = 0.64). It is because of variation of plastic flow processes towards a decrease in the degree of hardening in the material rolled according to the intensive technology. Cold deformation results in refining of the average grain size from 15.50 to 15.42 µm. In this case, extent of the grain boundary length L increased by 17.62% at an iteration step  commensurate with the average grain size which is indicated by a change in the fractal dimension according to L ~ δ1-D. Degree of the grain structure inhomogeneity was estimated using ratios of self-similarity of regions of fractal dimensions of the structure. The obtained results on the level of mechanical properties of fuel cladding tubes made of austenitic steel indicate advantage of the intensive technology over regular one that was confirmed by results of fractal modeling.


2021 ◽  
Vol 27 (3) ◽  
pp. 114-121
Author(s):  
Samiul Kaiser ◽  
Mohammad Salim Kaiser

The copper based alloys Al-bronze and α-brass containing each of 10wt% aluminum and zinc were prepared by casting. Afterwards, the specimens were cold-rolled with various percentages of deformation and the cold-rolled samples were aged subsequently at the varied time for four hours and temperatures ranging up to 500°C. Samples underwent characterizations by microhardness testing, electrical resistivity, optical properties, differential scanning calorimetry as well as microstructure analysis using an optical microscope. The results showed that the hardening of Cu-based alloys was taken place due to solid-solution hardening. Al addition accelerated the hardness through ageing due to the formation of various intermetallic copper aluminites into the aged alloy which was hard and brittle in nature. The resistivity decreased marginally through heat treatment due to the stage of stress relieving, recovery, precipitation coarsening as well as recrystallization and increased for arranging different intermetallics into the alloys. The microstructural study revealed that the cold rolled alloys content the different phases of elongated grain at the rolling direction. Meanwhile higher ageing temperatures at 500°C for one hour led to recrystallization and grain growth especially in pure copper and Cu-10Zn alloys.


Author(s):  
Igor Alex VAKULENKO ◽  
Sergey PLITCHENKO ◽  
Bulent KURT ◽  
Hangardas ASKEROV ◽  
Svetlana PROYDAK ◽  
...  

During a study of the combustion process of a direct polarity electric arc, a directly proportional dependence of the electric current value on the degree of cold plastic deformation of carbon steel used as an electrode was found. To calculate the value of the electric current during arc burning, in the indicated ratio, it was proposed to replace the surface tension force of the liquid metal with the surface tension of ferrite of plastically deformed carbon steel. Calculation of the ferrite’s surface tension value on the deformation degree of the steel under study through the size of the coherent scattering regions was used to explain the observed dependence of the electric current during arc burning. From the analysis of the considered correlation ratios, it was found that with an increase in the cold deformation degree, the refinement of the coherent scattering regions results in the ferrite’s surface tension increase and consequently, to an increase in the electric current during arc burning. Comparative analysis of the obtained results of calculating the value of electric current during arc burning through the surface tension of ferrite of cold-deformed carbon steel showed a fairly good coincidence with experimental data. The differences did not exceed 9%.


2021 ◽  
pp. 105-110
Author(s):  
Д.А. Потянихин ◽  
А.А. Синельщиков ◽  
Ко.Х. Мин

В работе представлены результаты моделирования в конечно-элементном программном комплексе ANSYS напряженно-деформированного состояния тонкостенной трубчатой заготовки из титанового сплава ОТ4 в процессе раздачи эластичной средой по жесткой матрице. Рассматривается осесимметричная матрица в виде тела вращения с криволинейной образующей. Задача решается в осесимметричной квазистационарной постановке. Конечно-элементная модель включает пуансон, матрицу, трубчатую заготовку, и эластичное рабочее тело. Пуансон перемещается в вертикальном направлении вниз, передавая усилие на деформируемую деталь через рабочее тело. Фрикционное взаимодействие происходит по закону Кулона. Проведен анализ напряженно-деформированного состояния детали в процессе формообразования. Исследовано распределение остаточных напряжений, упругое пружинение после снятия нагрузки и утонение стенок детали. Показана возможность получения детали типа «переходник» из титанового сплава ОТ4 холодным пластическим деформированием без нагрева заготовки. In this paper, the results of simulation of the stress-strain state of a thin-walled tubular blank made from titanium alloy OT4 in the ANSYS finite element software package in the process of expansion by an elastic medium in the rigid die are presented. The axisymmetric die in the form of a body of revolution with a curvilinear generatrix is considered. The problem is solved in an axisymmetric quasi-stationary setting. The finite element model includes a punch, a die, a tubular blank, and an elastic working body. The punch moves vertically downward, transmitting the force to the deformed tube through the working body. Frictional interaction occurs according to the Coulomb's law. The analysis of the stress-strain state of the deformed detail in the process of shaping is carried out. Distribution of residual stresses, elastic spring back after removal of the load and wall thinning of the detail are investigated. The possibility of obtaining the "adapter" type detail from titanium alloy OT4 by cold plastic deformation without heating the blank is shown.


Author(s):  
І. О Vakulenko ◽  
D. M Bolotova ◽  
S. V Proidak ◽  
B Kurt ◽  
A. E Erdogdu ◽  
...  

Purpose. The aim of this work is to assess the effect of ferrite grain size of low-carbon steel on the development of strain hardening processes in the area of nucleation and propagation of deformation bands. Methodology. Low-carbon steels with a carbon content of 0.06–0.1% C in various structural states were used as the material for study. The sample for the study was a wire with a diameter of 1mm. The structural studies of the metal were carried out using an Epiquant light microscope. Ferrite grain size was determined using quantitative metallographic techniques. Different ferrite grain size was obtained as a result of combination of thermal and termo mechanical treatment. Vary by heating temperature and the cooling rate, using cold plastic deformation and subsequent annealing, made it possible to change the ferrite grain size at the level of two orders of magnitude. Deformation curves were obtained during stretching the samples on the Instron testing machine. Findings. Based on the analysis of stretching curves of low-carbon steels with different ferrite grain sizes, it has been established that the initiation and propagation of plastic deformation in the jerky flow area is accompanied by the development of strain hardening processes. The study of the nature of increase at dislocation density depending on ferrite grain size of low-carbon steel, starting from the moment of initiation of plastic deformation, confirmed the existence of relationship between the development of strain hardening at the area of jerky flow and the area of parabolic hardening curve. Originality. One of the reasons for decrease in Luders deformation with an increase of ferrite grain size of low-carbon steel is an increase in strain hardening indicator, which accelerates decomposition of uniform dislocations distribution in the front of deformation band. The flow stress during initiation of plastic deformation is determined by the additive contribution from the frictional stress of the crystal lattices, the state of ferrite grain boundaries, and the density of mobile dislocations. It was found that the size of dislocation cell increases in proportion to the diameter of ferrite grain, which facilitates the development of dislocation annihilation during plastic deformation. Practical value. Explanation of qualitative dependence of the influence of ferrite grain size of a low-carbon steel on the strain hardening degree and the magnitude of Luders deformation will make it possible to determine the optimal structural state of steels subjected to cold plastic deformation.


Author(s):  
Vasyl Muzychuk

The article considers the process of forming the inner slot profile on a pipe billet by the method of cold plastic deformation, by compressing them with a matrix on a profile slotted mandrel (by the method of "covering" drawing). A comprehensive study of the mechanics of shaping products to assess their quality and study the possibility of improving the process itself. In the case of three-dimensional molding, the surface of plasticity depends on the history of deformation, which is determined by the change in the stress state with increasing accumulated intensity of deformation. The surface of plasticity in this case is not fixed and can be constructed using the criterion of deformability, which provides the position of the point of the fracture surface, taking into account the history of deformation. The planes of deformation and boundary surfaces of plasticity are constructed, which showed a sufficient margin of plasticity for the process of forming the inner splined profile. It is substantiated that when constructing the load trajectory in the space of dimensionless indicators and its type is unambiguously determined by the conditions of formation characteristic of the studied process and practically does not depend on the mechanical properties of the deformed metal. The areas of deformation closest to the failure are determined by indicators that take into account the influence of the first and third invariants of the stress tensor (lateral region and area of depressions of the profile relative to the process of forming the internal splined profile), in which the used plasticity reaches values = 0,34 ... 0,4. From the point of view of providing a margin of safety, such calculations must be performed taking into account the indicator that takes into account the influence of the third invariant of the stress tensor.


Sign in / Sign up

Export Citation Format

Share Document