scholarly journals Theory and practice of fatigue strength technological support in machinery

2018 ◽  
Vol 2018 (10) ◽  
pp. 38-42 ◽  
Author(s):  
Анатолий Тотай ◽  
Anatoliy Totay
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Surface Layer ◽  
Fatigue Strength ◽  
Theory And Practice ◽  
Surface Layers ◽  
Technological Support ◽  
Dislocations Density ◽  
Temperature Factors

On a basis of the theory of metal plastic deformation there are determined analytical ties between speed, power and temperature factors of machining with parameters of machinery surface layers defining their resistance to fatigue destructions. The paper reports the technological assurance options for resistance to fatigue by means of the control of such surface layer state parameters of machinery as dislocations density and a grain size of structure material.

scholarly journals ANALYTICAL APPROACH TO TECHNOLOGICAL SUPPORT OF FATIGUE LIMIT

2019 ◽  
Vol 2019 (3) ◽  
pp. 13-20
Author(s):  
Анатолий Тотай ◽  
Anatoliy Totay
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Surface Layer ◽  
Analytical Approach ◽  
Critical Density ◽  
Cycle Number ◽  
Technological Support ◽  
Dislocations Density ◽  
Technological Impact ◽  
First Time

In the paper on the basis of the theory of metal plastic deformation there are obtained analytical de-pendences of dislocations critical density and cycle number up to destruction caused by factors technological impact upon the surface under working. For the first time in complex there are taken into account such physical characteristics as an effort, temperature and speed of deformation in the area of cutting and strengthening. A tie between such parameters of surface layer state as a steel grain size and dislocations density is defined.

Surface Layers' Real Structure of Metals Exposed to Inhomogeneous Thermal Fields and Plastic Deformation

2010 ◽  
Vol 163 ◽  
pp. 59-63 ◽  
Author(s):  
Zdenek Pala ◽  
N. Ganev ◽  
Jan Drahokoupil ◽  
Alexej Sveshnikov
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Grain Size ◽  
Surface Layer ◽  
Real Structure ◽  
End Mill ◽  
Surface Layers ◽  
Thermal Fields ◽  
Mill Speed

Inhomogeneous thermal fields and plastic deformation are two basic phenomena present during surface creation and substantially determine future real structure of the surface layers. In the following, a closer look will be taken at some aspects connected with real structure of milled and ground steels. Impact of end-mill speed and thickness of removed layer on grain size, macroscopic and microscopic residual stress is discussed. Possibility of prestrained surface layer in ground steel has been examined on a set of five types of steels.

Investigation of the Impact of Orthogonal Cutting Processes on Nanocrystalline Surface Layer Generation

2013 ◽  
Vol 554-557 ◽  
pp. 2009-2020 ◽  
Author(s):  
Volker Schulze ◽  
Frederik Zanger ◽  
Florian Ambrosy
Keyword(s):  
Grain Size ◽  
Surface Layer ◽  
Cutting Force ◽  
Manufacturing Process ◽  
Orthogonal Cutting ◽  
Work Piece ◽  
Passive Force ◽  
Surface Layers ◽  
Cutting Processes ◽  
The Impact

The present work analyzes the influence of an orthogonal machining process on the generation of nanocrystalline surface layers. Thereby, AISI 4140 is used as work piece material. Metallic parts with a severe nanocrystalline grain refinement in the near-surface area show many beneficial properties. Such surface layers considerably influence the friction and wear characteristics of the work piece in a subsequent usage as design elements working under tribological loads. The focus of this paper is an experimental analysis of a finishing orthogonal cutting operation, carried out with a broaching machine, to generate nanocrystalline surface layers. The influence of process and geometry parameters on the generation of nanocrystalline surfaces is investigated with the aim to massively decrease the grain size in the work piece surface layer. Parameters that are studied and taken into account in the manufacturing process are cutting edge radius rβ, depth of cut h and cutting velocity vc. The cutting edge radius rβ is modified by a drag finishing process. The generation of nanocrystalline surface layers is especially influenced by the design of the uncoated carbide cutting tools. Additionally, cutting force Fc and passive force Fp are determined by a 3-component dynamometer to calculate the relationship between specific cutting force kc and specific passive force kp. The temperature beneath the clearance face is detected by a fiber optic pyrometer. These measurement methods and devices are applied to detect the impact of the most relevant measurement values occurring during machining and causing a drastic reduction of grain size in the surface layer. The evaluation of the manufacturing process is carried out by detailed analyses of the microstructural conditions in the surface layer after processing using a Focused Ion Beam (FIB) system. These material characterizations provide information about the surface engineering concerning the microstructural changes in the surface layer of the work piece due to finishing orthogonal cutting processes.

Ultrasonic Impact Treatment of Fine- and Coarse Grained Commercial Purity Titanium

2016 ◽  
Vol 1139 ◽  
pp. 12-15
Author(s):  
Rustam Hairullin ◽  
Anna Kozelskaya ◽  
Marina Kazachenok
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Surface Layer ◽  
Electron Backscatter Diffraction ◽  
Coarse Grained ◽  
Commercial Purity ◽  
Ultrasonic Impact Treatment ◽  
Commercial Purity Titanium ◽  
Wide Range ◽  
Purity Titanium

The grain size effect on surface morphology, microstructure and mechanical properties of commercial purity titanium specimens subjected to ultrasonic impact treatment was studied. It was found by atomic force microscope that ultrasonic impact treatment of titanium specimens resulted in surface corrugation happens due to their severe plastic deformation. The profile height of the corrugated surface depends on the grain size of specimens and varies in a wide range. The thicknesses of a modified surface layer of fine-and coarse grained titanium specimens were studied. Electron backscatter diffraction (EBSD) analysis revealed that the plastic deformation was accompanied by twin and low angle boundary formation in the surface layer of titanium specimens. The effect of ultrasonic impact treatment on the microhardness of the surface layer of the specimens under study was investigated.

Surface Nanocrystallization of Low Carbon Steel Induced by Circulation Rolling Plastic Deformation

2005 ◽  
Vol 475-479 ◽  
pp. 133-136 ◽  
Author(s):  
Xin Min Fan ◽  
Bosen Zhou ◽  
Lin Zhu ◽  
Heng Zhi Wang ◽  
Jie Wen Huang
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Surface Layer ◽  
Carbon Steel ◽  
Severe Plastic Deformation ◽  
Low Carbon Steel ◽  
Low Carbon ◽  
Surface Nanocrystallization ◽  
Average Grain Size ◽  
The Matrix

In this paper, the circulation rolling plastic deformation(CRPD) surface nanocrystallization technology is proposed based on the idea that the severe plastic deformation can induce grain refinement. The equipment of CRPD is designed and manufactured. A nanocrystallization surface layer was successfully obtained in a column sample of low carbon steel. The average grain size in the top surface layer is about 18 nm, and gradually increases with the distance from the surface. The hardness increases gradually from about 200HV0.1 in the matrix to about 600HV0.1 in the surface layer.

TECHNOLOGY OF COMBINED ELECTROMECHANOULTRASONIC TREATMENT OF SURFACE LAYERS OF MACHINE PARTS

2020 ◽  
Vol 2 ◽  
pp. 26-33
Author(s):  
V.R. EDIGAROV
Keyword(s):  
Plastic Deformation ◽  
Surface Layer ◽  
Residual Stresses ◽  
Ultrasonic Treatment ◽  
Mechanical Treatment ◽  
Surface Plastic Deformation ◽  
Surface Plastic ◽  
Surface Layers ◽  
Machine Parts ◽  
Acoustic Treatment

The technology of combined electro–mechanical–acoustic treatment is presented, which is a combination of electro–mechanical treatment and surface plastic deformation by ultrasonic treatment. Microhardness and residual stresses in strengthened EMUzO surface layer of machine parts investigated.

Technological Features of Obtaining of Nanostructured Coatings on TiNi Base by Magnetron Sputtering

2014 ◽  
Vol 1064 ◽  
pp. 160-164
Author(s):  
P.O. Rusinov ◽  
Zh.M. Blednova
Keyword(s):  
Grain Size ◽  
Surface Layer ◽  
Phase Composition ◽  
Experimental Design ◽  
Magnetron Sputtering ◽  
Performance Criteria ◽  
Surface Layers ◽  
Determining Factors ◽  
Process Studies

Using the methods of experimental design made ​​the choice determining factors for the calculation of modes magnetron sputtering coating SME steel 321H; received mathematical-statistical model that relates the performance criteria with the main parameters of the process. Studies on developing the technology of magnetron sputtering materials with shape memory TiNi-based study of the structure and formed surface layers showed that the recommended spraying regimes provided obtain a homogeneous quality of the surface layer with a grain size of 15 nm to 50 nm, chemical and phase composition which provides the memory effect.

scholarly journals Functional grading of viscoelastic defined hot mix asphalt layers

2020 ◽  
Vol 19 (3) ◽  
pp. 258-271
Author(s):  
Murat Bostancıoğlu ◽  
Keyword(s):  
Surface Layer ◽  
Fatigue Strength ◽  
Hot Mix Asphalt ◽  
Flexible Pavements ◽  
Field Studies ◽  
Real Field ◽  
Surface Layers ◽  
Mechanical Responses ◽  
Study Results

In the design of layered flexible pavements with the mechanistic-empirical (M-A) method, the material characterization of layers is critical for the correct calculation of mechanical responses. The surface layers of flexible pavements produced as hot mix asphalt (HMA) behave as a visco-elastic material under real field conditions. In this study, in which the HMA surface layer was defined viscoelastic by creep-compliance method, functional grading was applied to the surface layer at the same time to increase the fatigue strength of the pavement. Functional grading application was performed in the form of 3, 5, 7, and 9 sub-layers with linear and exponential functions. The pavement life values due to the mechanical responses that occurred in the pavement were determined by the Asphalt Institute and Shell methods. The study results show that the fatigue strength of the viscoelastic surface layer increases significantly as a result of functional grading. Especially in sections with exponential grading, an improvement of more than 10% was achieved even when a small number of sub-layers used. These results show that functional grading can also be successfully applied in field studies, and even with three sub-layers, significant improvements can be provided

scholarly journals Оn wear resistance of steel-containing composites under extreme friction conditions

2019 ◽  
Vol 62 (8) ◽  
pp. 621-626
Author(s):  
V. V. Fadin ◽  
A. V. Kolubaev ◽  
M. I. Aleutdinova
Keyword(s):  
Plastic Deformation ◽  
Wear Resistance ◽  
Surface Layer ◽  
Solid Solutions ◽  
High Wear Resistance ◽  
Dry Sliding ◽  
Extreme Conditions ◽  
Surface Layers ◽  
Strong Adhesion ◽  
Low Wear

The interrelation between the mechanisms of surface layer deterioration of powder composites and the elemental compositions of their primary structures under extreme conditions of friction was studied. Extreme conditions were set by sliding under high pressure (higher 100 MPa) in boundary lubrication or by dry sliding under high density electric current (higher 100 A/cm2). It caused plastic deformation of the surface layers and their deterioration due to lowcycle fatigue. High wear resistance of materials in such conditions should be achieved due to satisfactory stress relaxation in the surface layers. It was suggested that stresses should be relaxed due to local plastic deformation in vicinity of the emerging stress concentrators. The ease of plastic deformation (and ease of relaxation) should be ensured by reducing the doping of the composites structural components, i.e. due to the lack of solid solutions. It was shown that the composites having the Cu – steel (alloy) – TiC compositions obtained by the method of self-propagating high-temperature synthesis with simultaneous pressing of the burning charge had strong adhesion in the sliding contact and showed low wear resistance under high pressures boundary friction. The absence of solid solutions in the primary structure of the Cu – Fe – TiC composite corresponded to high wear resistance due to the absence of adhesion in the contact and easy stress relaxation. Composites of Cu – steel-graphite compounds, made by sintering in vacuum, showed strong adhesion in a dry sliding electrical contact and low wear resistance due to the high content of alloying elements. It was noted that the absence of solutions in the composite composition of Cu – Fe – graphite caused the absence of adhesion in contact and the corresponding high wear resistance. In addition, stresses in the surface layer were also relaxed by the formation of FeO oxide in the contact space during sliding with the current collector. Composites containing solid solutions were not capable of forming FeO oxide on the sliding surface. It was an additional reason for the low wear resistance realization. It was noted that solid solutions caused a decrease in the thermal conductivity of the surface layer. Therefore, it led to an increase in temperature gradients on the sliding surface and to a сorresponding acceleration of the friction zone deterioration.

scholarly journals Structural Transformations and Mechanical Properties of Metastable Austenitic Steel under High Temperature Thermomechanical Treatment

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 645
Author(s):  
Igor Litovchenko ◽  
Sergey Akkuzin ◽  
Nadezhda Polekhina ◽  
Kseniya Almaeva ◽  
Evgeny Moskvichev
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
High Temperature ◽  
Austenitic Steel ◽  
Structural Transformations ◽  
Initial State ◽  
Twin Boundaries ◽  
Metastable Austenitic Steel ◽  
Average Grain Size ◽  
Heating Up

The effect of high-temperature thermomechanical treatment on the structural transformations and mechanical properties of metastable austenitic steel of the AISI 321 type is investigated. The features of the grain and defect microstructure of steel were studied by scanning electron microscopy with electron back-scatter diffraction (SEM EBSD) and transmission electron microscopy (TEM). It is shown that in the initial state after solution treatment the average grain size is 18 μm. A high (≈50%) fraction of twin boundaries (annealing twins) was found. In the course of hot (with heating up to 1100 °C) plastic deformation by rolling to moderate strain (e = 1.6, where e is true strain) the grain structure undergoes fragmentation, which gives rise to grain refining (the average grain size is 8 μm). Partial recovery and recrystallization also occur. The fraction of low-angle misorientation boundaries increases up to ≈46%, and that of twin boundaries decreases to ≈25%, compared to the initial state. The yield strength after this treatment reaches up to 477 MPa with elongation-to-failure of 26%. The combination of plastic deformation with heating up to 1100 °C (e = 0.8) and subsequent deformation with heating up to 600 °C (e = 0.7) reduces the average grain size to 1.4 μm and forms submicrocrystalline fragments. The fraction of low-angle misorientation boundaries is ≈60%, and that of twin boundaries is ≈3%. The structural states formed after this treatment provide an increase in the strength properties of steel (yield strength reaches up to 677 MPa) with ductility values of 12%. The mechanisms of plastic deformation and strengthening of metastable austenitic steel under the above high-temperature thermomechanical treatments are discussed.

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