scholarly journals Analysis of Surface Properties of Nickel Alloy Elements Exposed to Impulse Shot Peening with the Use of Positron Annihilation

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7328
Author(s):  
Agnieszka Skoczylas ◽  
Kazimierz Zaleski ◽  
Radosław Zaleski ◽  
Marek Gorgol
Keyword(s):  
Surface Layer ◽  
Positron Annihilation ◽  
Nickel Alloy ◽  
Shot Peening ◽  
Positron Lifetime ◽  
Experimental Studies ◽  
Maximum Increase ◽  
Small Surface ◽  
The Mean ◽  
The Impact

The paper presents the results of experimental studies on the impact of impulse shot peening parameters on surface roughness (Sa, Sz, Sp, Sv), surface layer microhardness, and the mean positron lifetime (τmean). In the study, samples made of the Inconel 718 nickel alloy were subjected to impulse shot peening on an originally designed stand. The variable factors of the experiment included the impact energy, the diameter of the peening element, and the number of impacts per unit area. The impulse shot peening resulted in changes in the surface structure and an increase in surface layer microhardness. After the application of impulse shot peening, the analyzed roughness parameters increased in relation to post-milling values. An increase in microhardness was obtained, i.e., from 27 HV 0.05 to 108 HV 0.05 at the surface, while the maximum increase the microhardness occur at the depth from 0.04 mm to 0.08 mm. The changes in the physical properties of the surface layer were accompanied by an increase in the mean positron lifetime τmean. This is probably related to the increased positron annihilation in point defects. In the case of small surface deformations, the increase in microhardness was accompanied by a much lower increase in τmean, which may indicate a different course of changes in the defect structure consisting mainly in modification of the dislocation system. The dependent variables were subjected to ANOVA analysis of variance (it was one-factor analysis), and the effect of independent variables was evaluated using post-hoc tests (Tukey test).

scholarly journals Effect of Centrifugal Shot Peening on the Surface Properties of Laser-Cut C45 Steel Parts

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3635 ◽  
Author(s):  
Agnieszka Skoczylas ◽  
Kazimierz Zaleski
Keyword(s):  
Residual Stress ◽  
Surface Layer ◽  
Shot Peening ◽  
Experimental Studies ◽  
Combustion Products ◽  
Stress Distributions ◽  
Machining Center ◽  
Fold Reduction ◽  
Stress Layer ◽  
The Impact

This article presents the results of experimental studies of the impact of centrifugal shot peening parameters on the roughness, microstructure, and microhardness of the surface layer of laser-cut C45 steel parts. Residual stress distributions and the presence of iron oxides on the surface of these elements were also examined. Centrifugal shot peening tests were performed on an FV-580a vertical machining center while using a specially designed peening head. The parameters that were varied during centrifugal shot peening included tangential speed of the tool vg and feed rate vf. The use of centrifugal shot peening for finish machining of laser-cut C45 steel parts allowed for obtaining a four-fold reduction in the surface roughness parameters Ra and Rz. As a result of shot peening, the geometrical structure of the surface of the steel parts was modified and it acquired new beneficial features, such as large values of the rounding radii of the micropeaks and high material ratios (Rmrmax = 92%). At the same time, the surface layer was hardened (microhardness increased by 16%) and a compressive residual stress layer was produced on the surface of the workpieces. Additionally, as the shot impacted the processed surface, combustion products were “blasted” or “sheared” off it. Shot peening using the proposed technique can be successfully performed while using CNC machines.

scholarly journals Selected Properties of the Surface Layer of C45 Steel Parts Subjected to Laser Cutting and Ball Burnishing

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3429 ◽  
Author(s):  
Agnieszka Skoczylas ◽  
Kazimierz Zaleski
Keyword(s):  
Surface Layer ◽  
Residual Stresses ◽  
Laser Cutting ◽  
Experimental Studies ◽  
Hardened Layer ◽  
Ball Burnishing ◽  
Absolute Value ◽  
The Impact ◽  
Compressive Residual Stresses

In this article, we report the results of experimental studies on the impact of ball burnishing parameters on the roughness, microstructure and microhardness of the surface layer of laser-cut C45 steel parts. We also analysed the distribution of residual stresses generated in the surface layer of these parts. Laser-cut parts often require finishing to improve the quality of their surface. The tests performed in this study were aimed at assessing whether ball burnishing could be used as a finishing operation for parts of this type. Ball burnishing tests were performed on an FV-580a vertical machining centre using a mechanically controlled burnishing tool. The following parameters were varied during the ball burnishing tests: burnishing force Fn, path interval fw and the diameter of the burnishing ball dn. Ball burnishing of laser-cut C45 steel parts reduced the surface roughness parameters Sa and Sz by up to 60% in relation to the values obtained after laser cutting. Finish machining also led to the reorganization of the geometric structure of the surface, resulting in an increase in the absolute value of skewness Ssk. This was accompanied by an increment in microhardness (maximum microhardness increment was ΔHV = 95 HV0.05, and the thickness of the hardened layer was gh = 40 µm) and formation of compressive residual stresses in the surface layer.

Evaluation of olive grove management on various soils at the micro-catchment scale with the AnnAGNPS model to quantify their impacts on organic carbon

2020 ◽  
Author(s):  
Encarnación Taguas ◽  
Ronald L. Bingner ◽  
Henrique Momm ◽  
Robert R. Wells ◽  
Martin Locke
Keyword(s):  
Organic Carbon ◽  
Sandy Loam ◽  
Experimental Studies ◽  
Life Time ◽  
Conventional Tillage ◽  
Catchment Scale ◽  
Maximum Increase ◽  
Small Catchment ◽  
Silty Loam ◽  
The Impact

<p>Soil organic carbon (SOC) stock changes are crucial to identify the risk of desertification in fragile areas such as the Mediterranean Basin and to fulfill environmental protection global conventions. In Spain, 48% of the world’s olive oil is produced with 2.6 Mha dedicated to the crop and there is clear concern over the carbon balance in the context of climate change and the resulting loss of productivity. In this work, 108 scenarios were prepared with the model AnnAGNPS in a small catchment of extensive olive groves by considering the impact of soil type and management using 6 different soil types (with textures sandy, S; sandy loam, Slo; loam, L; clay loam, Clo; silty loam clay, SiLoC; clay, C), 3 different managements (no till, NT; conventional tillage, CT, and cover crop, SC), 3 types of fertilization (two organic with different rates, F2 and F3,  and another inorganic F1) and 2 contrasting reach organic carbon half-life time (0.1 day-730 days). The consistency of the simulated values of annual OC attached to the sediments and of variations of ground SOC (h=200 mm) were evaluated and compared in the context of the region of Andalusia.</p><p>There were significant differences of annual values of the sediment OC for the scenarios of soil and management with a range variation between 0.0 kg.ha<sup>-1</sup> and 368.9 kg.ha<sup>-1</sup>. In addition, S and SC showed the lowest variability intervals while Clo and NT had the highest sediment OC and variation ranges. For the SOC pools, the effects of soil and fertilization types were more evident than of the management. The combination C-SC-F3 presented the maximum increase of SOC (0.150 mg OC.g<sup>-1</sup>soil.y<sup>-1</sup>) while the combination Slo-NT-F1 presented the minimum (0.080 mg OC.g<sup>-1</sup>soil.y<sup>-1</sup>). Despite specific calibrations needed to quantify OC balances, the consistency of the hydrological and erosive parameterization based on the abundance of experimental studies supports the use of AnnAGNPS for simulating the OC loss in agricultural catchments.</p>

scholarly journals Effect of Wave Thermal Deformation Hardening on the Microhardness of the Surface Layer of Steel Parts

2021 ◽  
Vol 2131 (5) ◽  
pp. 052023
Author(s):  
A Kirichek ◽  
S Silantyev ◽  
S Fedonina ◽  
A Yashin
Keyword(s):  
Surface Layer ◽  
Comparative Studies ◽  
Thermal Deformation ◽  
Thermal Strain ◽  
Experimental Studies ◽  
Initial State ◽  
Maximum Increase ◽  
Processing Modes ◽  
Deformation Hardening ◽  
Deformation Treatment

Abstract Preliminary experimental studies of the possibility of increasing the microhardness of the surface layer of the material by the method of wave thermodeformational hardening on the example of austenitic steel class 12X18H10T are carried out. Comparative studies on the hardening of the material with and without heating were also carried out. The possibility of a significant increase in the maximum microhardness in the range from 25 to 50% at a depth of up to 0.6 mm, depending on the hardening mode, in comparison with the deformation treatment in the “cold” state is established. The area of technological modes providing the maximum increase of microhardness in the surface layer is revealed, in particular, the temperature of the treated surface should be in the range from 200°C to 400°C. At the same time, the achieved microhardness values exceed the initial one by 1.8…2.2 times, depending on the processing modes. It is also found that when choosing rational processing modes, the combined wave thermal strain hardening can significantly increase the hardening depth to 4.2 mm of the surface layer compared to the initial state. To establish the possibility of improving the performance of combined processing requires additional research.

scholarly journals The Effect Of Pow-Tega As Interactive Technique To Improve Students’ Speaking Ability At Senior High School Student

2021 ◽  
Vol 12 (4) ◽  
pp. 625-630
Author(s):  
Netty Huzniati Andas, Et. al.
Keyword(s):  
Classroom Environment ◽  
Test Score ◽  
Video Recording ◽  
Experimental Studies ◽  
Teaching Technique ◽  
Post Test ◽  
Speaking Skill ◽  
The Mean ◽  
Significant Stage ◽  
The Impact

Speaking is the art of conveying ideas and feelings by generating and sharing meaning through oral contact. Pow-Tega is a speaking skill teaching technique that combines a power teaching technique with a game to allow students to practice their speaking skills. Students' focus and excitement in speaking are developed using the power teaching technique. Students were inspired to study while playing the game because the classroom environment was more colorful. Researchers used a quantitative method by assigning pre-experimental studies with one group pre-test and post-test to determine the impact of the Pow-Tega technique on students' speaking performance. This study included 33 students as participants. The researchers used a spoken test and video recording to gather data. Before beginning treatment, researchers gave all of the samples a pre-test, then began treatment by using the Pow-Tega Technique for six meetings, and eventually, researchers gave all of the samples a post-test. The results revealed that the mean post-test score (3,93) was higher than the pre-test score (3,39). Furthermore, at the significant stage of 0,05 and degree of freedom -19, the ttest (6,75) was higher than the ttable (2.093). H0  has been  refused, while H1 has been accepted. That means there was a significant effect of students’ speaking ability after they were taught by using Pow-Tega.

scholarly journals The Effect of Simulation Technique on Academic Achievement: A Meta-Analysis Study

2020 ◽  
Vol 5 (1) ◽  
pp. 17-36
Author(s):  
Tarik Talan
Keyword(s):  
Academic Achievement ◽  
Publication Bias ◽  
Meta Analysis ◽  
Experimental Studies ◽  
Subject Area ◽  
Simulation Technique ◽  
Bias Analysis ◽  
Analysis Study ◽  
The Mean ◽  
The Impact

This research aims to examine the experimental studies on the impact of simulation technique on students' academic achievement using the meta-analysis method. The previous studies that could be meta-analyzed were examined based on the criteria set out in this study. Finally, 91 studies that were conducted between 2010-2020 years and met the inclusion criteria were subjected to meta-analysis. The sample of the research consisted of 7575 participants. According to the results of the analysis performed using the random-effects model, the mean effect size was calculated as g=0.759 with a standard error of 0.075. Based on the findings, the simulation technique can be said to have a broad impact on students' academic achievement. The results of the publication bias analysis revealed that the present meta-analysis study had no publication bias. On the other hand, the results of the moderator analysis revealed that the impact of the simulation technique on the students' academic achievement did not differ by the teaching levels, course/subject area, and application times, however, it differed by the sample size.

scholarly journals Influence of Shot Peening on Abrasion Wear in Real Conditions of Ni-Cu-Ausferritic Ductile Iron

2016 ◽  
Vol 61 (4) ◽  
pp. 1985-1990
Author(s):  
A. N. Wieczorek
Keyword(s):  
Surface Layer ◽  
Abrasive Wear ◽  
Ductile Iron ◽  
Shot Peening ◽  
Residual Austenite ◽  
Wear Properties ◽  
Surface Layers ◽  
Cast Irons ◽  
Dynamic Surface ◽  
The Impact

Abstract The paper presents results of the wear tests of chain wheels made of austempered ductile iron with various content of residual austenite. The aim of this study was to demonstrate the impact of the dynamic surface treatment (shot peening) on wear properties of surface layers of the chain wheels tested that were subjected to the action of quartz abrasive. Apart from determining the value of the abrasive wear, examinations of the magnetic phase content in the microstructure were carried out and plots of hardness of the surface layer as a function of the distance from the surface and microstructure of the materials were prepared. Based on the results, the following was found: an increase in the abrasive wear and a reduction in the hardness of the surface layer of chain wheels subjected to shot peening, as well as reduction of susceptibility to negative action of the shot for cast irons with the structure of upper ausferrite.

Laser Modification of Metal Cutting Tool: Assessment of the Influence on Wear Resistance and Quality of the Processed Surface

2020 ◽  
Vol 836 ◽  
pp. 118-123
Author(s):  
S.K. Kargapol’tsev ◽  
V.I. Shastin ◽  
V.E. Gozbenko
Keyword(s):  
Wear Resistance ◽  
Surface Layer ◽  
Metal Cutting ◽  
Cutting Tool ◽  
Experimental Studies ◽  
Machined Surface ◽  
Laser Modification ◽  
Metal Cutting Tool ◽  
The Impact

The paper reflects the relevance of hardening the working surfaces of the tool, where the surface layer plays a fundamental role. The main factors determining the wear resistance of the tool and their influence on the quality of the processed surface are analyzed. The purpose of the research is to study the effect of laser modification of tool alloys on wear resistance and on the roughness parameters of the machined surface. A small-sized drill bit (steel P6M5) and carbide inserts T15K6 are used as objects of research. The paper presents the results of experimental studies on the impact of laser radiation on the microstructure of materials, indices of wear resistance and quality parameters of the treated surface. It is established that there is a certain relationship between these indices. The modes of laser modification of the tool most acceptable for practical use are determined. Along with an increase in the wear resistance of a metal-cutting tool, a manifestation of the effect of an increase in surface roughness indices is found and experimentally confirmed. It is established that hardening of the surface layer is caused by structural and phase transformations with enhanced physical and mechanical properties, and the roughness indices depend on the degree of dispersion (amorphization) of the modified layer.

scholarly journals Gradient Microstructure Induced by Surface Mechanical Attrition Treatment (SMAT) in Magnesium Studied Using Positron Annihilation Spectroscopy and Complementary Methods

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4002
Author(s):  
Konrad Skowron ◽  
Ewa Dryzek ◽  
Mirosław Wróbel ◽  
Paweł Nowak ◽  
Marianna Marciszko-Wiąckowska ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Positron Lifetime ◽  
Electron Backscatter Diffraction ◽  
Electrochemical Corrosion ◽  
Positron Beam ◽  
Corrosion Current ◽  
Surface Mechanical Attrition Treatment ◽  
Mechanical Attrition ◽  
Gradient Microstructure ◽  
The Mean

Surface mechanical attrition treatment (SMAT) was used to generate a gradient microstructure in commercial grade magnesium. Positron annihilation lifetime spectroscopy and variable energy positron beam measurements, as well as microhardness tests, electron backscatter diffraction, X-ray diffraction, and electrochemical corrosion tests, were used to investigate the created subsurface microstructure and its properties. It was found that SMAT causes an increase in dislocation density and grain refinement which results in increased hardness of the subsurface zone. The mean positron lifetime values indicate trapping of positrons in vacancies associated with dislocations and dislocation jogs. The increase of the SMAT duration and the vibration amplitude influences the depth profile of the mean positron lifetime, which reflects the defect concentration profile. Electrochemical measurements revealed that the structure induced by SMAT increases the susceptibility of magnesium to anodic oxidation, leading to the enhanced formation of hydroxide coverage at the surface and, as a consequence, to the decrease in corrosion current. No significant effect of the treatment on the residual stress was found.

Positron Lifetime in Deformed AlSi10.9Mg0.17Sr0.06 Alloys

2007 ◽  
Vol 261-262 ◽  
pp. 55-60 ◽  
Author(s):  
M.A. Abdel-Rahman ◽  
M.S. Abdallah ◽  
Emad A. Badawi
Keyword(s):  
Dislocation Density ◽  
Positron Annihilation ◽  
Material Science ◽  
Positron Lifetime ◽  
Defect Concentration ◽  
Positron Annihilation Lifetime Spectroscopy ◽  
Positron Annihilation Lifetime ◽  
Nuclear Techniques ◽  
Mean Lifetime ◽  
The Mean

Positron annihilation lifetime spectroscopy (PALS) is one of the nuclear techniques used in material science. (PALT) measurements are used to study the behaviour of the defect concentration in a set of AlSi10.9Mg0.17Sr0.06 alloys. It has been shown that positrons can become trapped at imperfect locations in solids, and that their mean lifetime can be influenced by changes in the concentration of such defects. No changes have been observed in the mean lifetime values following saturation of the defect concentration. The mean lifetime and trapping rates were studied for samples deformed up to 34.9 %. The concentrations of defects range vary from 5.194x1015 to 1.934x1018 cm-3 for thickness reductions of 2.2 to 34.9 %. The range of the dislocation density varies from 1.465x 108 to 5.454x1010 cm/cm3 over the same range of deformations.

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