scholarly journals The Effect of Chip Binding on the Parameters of the Case-Hardened Layer of Tooth Surfaces for AMS 6308 Steel Gears Processed by Thermochemical Treatment

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1155
Author(s):  
Robert Fularski ◽  
Ryszard Filip
Keyword(s):  
Mechanical Performance ◽  
Negative Impact ◽  
Gear Tooth ◽  
Surface Hardness ◽  
Thermochemical Treatment ◽  
Hardened Layer ◽  
Case Depth ◽  
Machining Process ◽  
Case Hardening ◽  
Power Skiving

The following article describes influence of pressure welded or bound chips to the gear tooth flank and/or the tooth root on a carburized case and surface layer hardness of Pyrowear 53 steel gears, machined by Power Skiving method. This paper is focused only on one factor, the chips generated while forming gear teeth by power skiving, which could result in local changes in the carburized case parameters as a negatively affecting point of mechanical performance of the carburized case. The chips, due to the specifics of the power skiving process and the kinematics of tooth forming, could be subject to the phenomena of pressure welding or binding of chips to the tooth. During the carburizing stage of the downstream manufacturing processes, the chips form a diffusion barrier, which ultimately could result in localized changes in the carburized case. This work was an attempt to answer the question of how and to what extent the chips affect the case hardening. Performed simulations of chips by a generating cupper “spots”, mentioned in the study, represent a new approach in connection with minimization of errors, which could appear during carbon case depth and case hardness analysis for typical chips, generated during the machining process—assurance that a complete chip was bound to the surface. Hardness correlation for zones, where the chip appears with areas free of chips, gives simple techniques for assessment. Performed tests increased the knowledge about the critical size of the chip—1.5 mm, which could affect the case hardening. Obtained experimental test results showed that the appearance of chip phenomena on the gear tooth might have a negative impact on a carburized case depth and hardened layer.

scholarly journals Effect of Gaseous carburizing thermochemical treatment on tribological behavior of Ti–6Al–4V alloy

2021 ◽  
Vol 15 (58) ◽  
pp. 179-190
Author(s):  
Fedaoui Kamel ◽  
Amar Talhi ◽  
Mohamed Zine Touhami
Keyword(s):  
Wear Resistance ◽  
Treatment Time ◽  
Surface Hardness ◽  
Thermochemical Treatment ◽  
Microscopic Analysis ◽  
Hardness Test ◽  
Indentation Load ◽  
Case Hardening ◽  
Resistance To Wear ◽  
Loss Of Mass

This study, concerns the improvement of the hardness and resistance to wear of the Ti-6Al-4V alloy surface by means of thermochemical treatment, for obtaining coatings on the Ti-6Al-4V alloy gives performance of resistance to wear phenomena. Three-thermochemical treatment time (2h, 4h, and 6h) was chosen for investigation of the effect of such treatment on this alloy. The hardness test under an indentation load of 50 gf with a Vickers pyramidal indenter revealed that the surface hardness is 335 Hv for the untreated samples. On the other hand the hardness reaches approximately 1500 Hv during gas cementation at 930 °C for variable times (2h, 4h, 6h) followed by quenching at 840 °C in an oil medium, which was accompanied by a significant improvement in wear resistance. The characterization of the modified surface layers was made by means of a microscopic analysis and by X-ray diffraction. The case-hardening made it possible to obtain a wear resistance greater than that of the alloy not treated, minimal loss of mass by dry friction and an improvement in roughness as well as a good coefficient of friction.

scholarly journals PROPERTIES OF TUBES FROM Zr-1% Nb ALLOY AFTER THERMOCHEMICAL TREATMENT AND HYDROGENATION

2021 ◽  
pp. 84-87
Author(s):  
V.S. Trush ◽  
V.N. Voyevodin ◽  
P.I. Stoev ◽  
V.N. Fedirko ◽  
A.G. Lukyanenko ◽  
...  
Keyword(s):  
Zirconium Alloy ◽  
Gaseous Medium ◽  
Surface Hardness ◽  
Thermochemical Treatment ◽  
Hardened Layer ◽  
Hydrogen Saturation ◽  
Gaseous Media ◽  
Positive Effect ◽  
Physical And Mechanical Characteristics

The influence of treatment in controlled gas environments with subsequent hydrogenation on the physical and mechanical characteristics of the Zr-1% Nb zirconium alloy has been investigated. The surface hardness and the size of the diffusion-hardened layer of the ring-samples cut from fuel tubes from the Zr-1% Nb alloy after treatment in oxygen- and nitrogen-containing gaseous media with subsequent saturation with hydrogen have been established. The influence of the parameters of the gaseous medium and the modes of thermochemical treatment (TCT) of specimens-rings on the destructive stresses under static load at temperatures of 20 and 380 °C is shown. It was revealed that treatment in the investigated gas environment increases the resistance to hydrogen saturation and has a positive effect on the long-term strength of ring specimens from the zirconium alloy Zr-1% Nb.

scholarly journals Selection of Optimal Thermochemical Treatment of Steel Guides of Yarn

2019 ◽  
Vol 27 (6(138)) ◽  
pp. 27-33
Author(s):  
Stanisław Płonka ◽  
Robert Drobina ◽  
Dariusz Jędrzejczyk ◽  
Jacek Postrożny
Keyword(s):  
Surface Layer ◽  
Thermochemical Treatment ◽  
Pairwise Comparison ◽  
Case Depth ◽  
Case Hardening ◽  
Ring Spinning ◽  
Individual Decisions ◽  
The Individual ◽  
Optimisation Procedure ◽  
Selection Of

This paper presents a method of selection of an optimal (the best possible) thermochemical treatment of a steel guide of yarn for a ring spinning frame with the use of an optimisation procedure based on assumed criteria, and with consideration of their importance. Yarn guides for a ring spinning frame were manufactured from three brands of steel and were subjected to the following types of thermochemical treatment: 50SiCr4 steel (chrome hardening, diffusion boronising, and titanising); 41CrAlMo7 steel (nitrosulfiding and nitrogen case hardening), and C45 steel (diffusion boronizing). Unit manufacturing costs and six criteria of manufacturing quality: four parameters of surface texture (Rq, Rp, RΔq, rw), maximal hardness of the surface layer (HV0,1), and the case depth of the surface layer (gww), were taken as criteria for assessment. Values of the assessment criteria obtained from calculations and measurements were subjected to normalisation. The knowledge of experts and importance matrix B evaluated with the use of the Saaty method (consisting in pairwise comparison of the successive criteria) were used to determine the importance of the criteria taken for the assessment. Using the Power method, eigenvalues of matrix B were found, as well as corresponding coordinates yt of the eigenvector, which are simultaneously the weights of the corresponding criteria. Normalised decisions were created in the next step by raising each component of the normalised assessments to a power equal to the corresponding weight. In the last step of the procedure, a single optimal lining-up was created comprising the smallest s-th components of the individual decisions d1, d2, …, dm. The best variant of the thermochemical treatment was recognised as corresponding to the largest component of the optimal lining-up, which in our case is the diffusion boronizing.

scholarly journals Influence of Shot Peening on the Isothermal Fatigue Behavior of the Gamma Titanium Aluminide Ti-48Al-2Cr-2Nb at 750 °C

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1083
Author(s):  
Christoph Breuner ◽  
Stefan Guth ◽  
Elias Gall ◽  
Radosław Swadźba ◽  
Jens Gibmeier ◽  
...  
Keyword(s):  
Residual Stresses ◽  
Shot Peening ◽  
Elevated Temperatures ◽  
Stress Amplitude ◽  
Negative Impact ◽  
Fatigue Behavior ◽  
Surface Hardness ◽  
Fatigue Tests ◽  
Positive Effects ◽  
Isothermal Fatigue

One possibility to improve the fatigue life and strength of metallic materials is shot peening. However, at elevated temperatures, the induced residual stresses may relax. To investigate the influence of shot peening on high-temperature fatigue behavior, isothermal fatigue tests were conducted on shot-peened and untreated samples of gamma TiAl 48-2-2 at 750 °C in air. The shot-peened material was characterized using EBSD, microhardness, and residual stress analyses. Shot peening leads to a significant increase in surface hardness and high compressive residual stresses near the surface. Both effects may have a positive influence on lifetime. However, it also leads to surface notches and tensile residual stresses in the bulk material with a negative impact on cyclic lifetime. During fully reversed uniaxial tension-compression fatigue tests (R = −1) at a stress amplitude of 260 MPa, the positive effects dominate, and the fatigue lifetime increases. At a lower stress amplitude of 230 MPa, the negative effect of internal tensile residual stresses dominates, and the lifetime decreases. Shot peening leads to a transition from surface to volume crack initiation if the surface is not damaged by the shots.

Study of Quenching Organization Property under Wind Cooling Condition

2014 ◽  
Vol 487 ◽  
pp. 682-686
Author(s):  
Fu Quan Tu ◽  
Yang Mao ◽  
Ren Bo Xu
Keyword(s):  
Surface Hardness ◽  
Hardened Layer ◽  
Spray Cooling ◽  
Cooling Time ◽  
Cooling Condition ◽  
Micro Structure ◽  
Cross Sectional ◽  
Quenching Process ◽  
Quenching Time ◽  
Heavy Rail

In this paper, the steel of U71Mn specifications for 60kg/m heavy rail is seen as a research object. Experimental method is employed to study the heavy rail hardened layer, including surface hardness, micro-structure and cross-sectional hardness under different cooling time during quenching. Experimental results showed that obtained heavy rail after wind cooling quenching finally met the Tb/T2344-2003 43-75 kg/m standard. Best quenching treatment condition is found and the defect is reduced to large extent when quenching time is 40 seconds, cooling time is 40 to 45 seconds, superior to the traditional spray cooling condition. These results provide an important reference for the quenching process of heavy rail.

Basic Understanding of Gears

2005 ◽  
pp. 1-18
Keyword(s):  
Gear Tooth ◽  
Heat Treating ◽  
Case Hardening ◽  
Basic Understanding ◽  
Gear Manufacturing ◽  
Manufacturing Methods ◽  
Processing Steps ◽  
Selection Of

Abstract This chapter begins with a review of some of the terms used in the gear industry to describe the design of gears and gear geometries. It then discusses the types of gears that operate on parallel shafts, intersecting shafts, and nonparallel and nonintersecting shafts. Next, the processes involved in the selection of gear are discussed, followed by information on the basic stresses applied to a gear tooth, the strength of a gear tooth, and the most widely used gear materials. Further, the chapter briefly reviews gear manufacturing methods and the heat treating processing steps including prehardening processes, through hardening, and case hardening processes.

scholarly journals Evaluation of contact fatigue risk of a carburized gear considering gradients of mechanical properties

Friction ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 1039-1050
Author(s):  
Wei Wang ◽  
Huaiju Liu ◽  
Caichao Zhu ◽  
Jinyuan Tang ◽  
Chenxu Jiang
Keyword(s):  
Mechanical Properties ◽  
Fatigue Failure ◽  
Equivalent Stress ◽  
Contact Fatigue ◽  
Surface Hardness ◽  
Engineering Practice ◽  
Case Hardening ◽  
Failure Risk ◽  
Spalling Failure ◽  
Carburized Gear

AbstractCarburized gears are widely used in geared machines such as wind turbines. Contact fatigue problems occur in engineering practice, reducing reliabilities of machines. Contact fatigue failures are related to many factors, such as gradients of mechanical properties of the hardening layer. In this work, an elastic-plastic contact model of a carburized gear is developed based on the finite element method to evaluate contact fatigue failure risk, considering variations in hardness and strength. The Dang Van multiaxial equivalent stress is calculated via Python coding within the Abaqus framework. The gradient of yield strength along the depth from case to core is considered. The concept of local material fatigue failure risk is defined to evaluate the probability of pitting failure. The effects of design factors, such as the case hardening depth (CHD), surface hardness, and contact pressure on fatigue failure risk, are studied. As the CHD increases or the surface hardness decreases, the risk of deep spalling failure reduces. The increase in surface hardness leads to a decreased risk of pitting failure, while the variation in CHD hardly affects the pitting failure risk.

Effect of Gear-Side Case-Hardening on Residual Stresses of Case-Hardened Gears

2000 ◽  
Author(s):  
Kouitsu Miyachika ◽  
Satoshi Oda ◽  
Hiroshige Fujio
Keyword(s):  
Residual Stresses ◽  
Three Dimensional ◽  
Case Depth ◽  
Case Hardening ◽  
3D Fem ◽  
Face Width ◽  
Dimensional Finite Element ◽  
The Face ◽  
Standard Pressure ◽  
Three Dimensional Finite Element

Abstract This paper presents a study on effects of the case depth, the case-hardened part, the face width, the rim thickness and the standard pressure angle on residual stresses of case-hardened gears. A heat conduction analysis and an elastic-plastic stress analysis for the case-hardening process of spur gears were carried out by the three-dimensional finite-element method (3D-FEM), and then residual stresses were obtained. It was found that the compressive residual stress σ*θ = 30° at Hofer’s critical section of the end of the face width is smaller in magnitude than that of the middle of the face width, and that the absolute value of σ*θ = 30° of the middle of the face width decreases owing to case-hardening the gear-side and the decreasing rate increases with an increasing case depth and a decreasing face width.

scholarly journals Nonuniform Woven Solar Shading Screens: Shading, Mechanical, and Daylighting Performance

2019 ◽  
Vol 11 (20) ◽  
pp. 5652 ◽  
Author(s):  
Yao Lu ◽  
Hankun Lin ◽  
Siwei Liu ◽  
Yiqiang Xiao
Keyword(s):  
Solar Radiation ◽  
Mechanical Performance ◽  
Structural Strength ◽  
Negative Impact ◽  
Optical Performance ◽  
Clear View ◽  
Performance Factors ◽  
Ansys Simulation ◽  
Solar Shading ◽  
Optimal Configurations

This study investigated the potential of using a nonuniform woven panel with nonuniform strips—thick sticks and thin battens—as an external solar shading screen that addressed daylighting, shading, and mechanical performance factors. The sustainable material, namely, bamboo, was used as the demonstration material for the screen. An on-site experiment and ANSYS simulation were carried out to investigate the basic solar optical performance and structural strength of the proposed screen, respectively. Then, a series of daylighting simulations were conducted to optimize the configuration of the screen. The results showed that the nonuniform woven solar shading screen reduced up to 80.3% of the solar radiation gain in a room during summer months while ensuring a relatively even distribution of useful daylight during the year. Moreover, the screen effectively reduced the negative impact of glare to a level below “imperceptible” and enabled a relatively clear view through the window and shading. Regarding the structural strength, the screen with a size smaller than or equal to 1 × 1 m withstood a wind load of 12 m/s. Furthermore, this study proposed two optimal configurations: a screen woven of square sticks and battens with a distance of 10 mm between them, and a screen woven of round sticks and battens with a distance of 8 mm between them. This study illustrated the superiority of the nonuniform woven solar shading screens, which supports a wider application of solar shading screens made of other materials with similar structures and reflectance values.

scholarly journals A Study on the Effect of Carbon Nanotubes’ Distribution and Agglomeration in the Free Vibration of Nanocomposite Plates

2020 ◽  
Vol 6 (4) ◽  
pp. 79
Author(s):  
D. S. Craveiro ◽  
M. A. R. Loja
Keyword(s):  
Carbon Nanotubes ◽  
Elastic Properties ◽  
Natural Frequencies ◽  
Mechanical Performance ◽  
Negative Impact ◽  
Free Vibrations ◽  
Mode Shapes ◽  
The Finite Element Method ◽  
Agglomeration Effect ◽  
Performance Predictions

The present work aimed to characterize the free vibrations’ behaviour of nanocomposite plates obtained by incorporating graded distributions of carbon nanotubes (CNTs) in a polymeric matrix, considering the carbon nanotubes’ agglomeration effect. This effect is known to degrade material properties, therefore being important to predict the consequences it may bring to structures’ mechanical performance. To this purpose, the elastic properties’ estimation is performed according to the two-parameter agglomeration model based on the Eshelby–Mori–Tanaka approach for randomly dispersed nano-inclusions. This approach is implemented in association with the finite element method to determine the natural frequencies and corresponding mode shapes. Three main agglomeration cases were considered, namely, agglomeration absence, complete agglomeration, and partial agglomeration. The results show that the agglomeration effect has a negative impact on the natural frequencies of the plates, regardless the CNTs’ distribution considered. For the corresponding vibrations’ mode shapes, the agglomeration effect was shown in most cases not to have a significant impact, except for two of the cases studied: for a square plate and a rectangular plate with symmetrical and unsymmetrical CNTs’ distribution, respectively. Globally, the results confirm that not accounting for the nanotubes’ agglomeration effect may lead to less accurate elastic properties and less structures’ performance predictions.

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