Influence of work material microstructure on vibrations when machining cast Ti-6Al-4V

2015 ◽  
Vol 84 (9-12) ◽  
pp. 2277-2291 ◽  
Author(s):  
Stefan Cedergren ◽  
Constantinos Frangoudis ◽  
Andreas Archenti ◽  
Robert Pederson ◽  
Göran Sjöberg
Keyword(s):  
Material Microstructure ◽  
Work Material

Effect of Local Heating on the Mechanical Characteristics of Repaired Automotive Panels

2019 ◽  
Vol 56 (4) ◽  
pp. 750-758
Author(s):  
Nicolae Navodariu ◽  
Mihai Branzei ◽  
Robert Ciocoiu ◽  
Ion Ciuca ◽  
Razvan Coman ◽  
...  
Keyword(s):  
Mechanical Characteristics ◽  
Cold Working ◽  
Local Heating ◽  
Thin Sheet ◽  
Heating Time ◽  
Steel Plates ◽  
Maximum Temperature ◽  
Material Microstructure ◽  
Technology Process ◽  
Automotive Panels

Flame straightening is a technology process used to eliminate deformations. This method relies on local heating of the material to correct geometry or damaged parts. In the local automobile services its main use is for repairs of less critical deformed components. The maximum temperature and thermal gradient, heating time, cooling rate and number of heating cycles affect the mechanical properties since local heating can alter material microstructure. The aim of this research was to determine the mechanical characteristics of thin steel plates repaired by local heating associated with plastic deformation (similar to hot working) and cold straightening (similar to local cold working) for automotive side and door panels made of structural steel. Thin sheet plates, 0.9mm thickness, were deformed by impact and repaired by local heating using the flame and induction heating then plastically deformed while hot as well as straightened without heating. The heat repaired samples were studied by light microscopy to determine microstructure change and samples were tensile tested to determine their mechanical characteristics. Local excessive grain growth generates anisotropy, the assembly behaves as a composite material with regions that show significant plastic deformations while others little or no deformations at al. Without procedures adjusted to each material repairs involving heating are to be avoided, cold working should be employed when replacement is not possible.

Morphology and Topology of Coherent Scattering Regions of the Fe-Mn-C Steel Fine Structure

2015 ◽  
Vol 1085 ◽  
pp. 84-90
Author(s):  
Anna P. Zykova ◽  
Irina Kurzina ◽  
Mihail Yu. Novomejsky ◽  
Yuriy D. Novomejsky
Keyword(s):  
Fine Structure ◽  
Hyperfine Structure ◽  
Coherent Scattering ◽  
Technological Properties ◽  
Material Microstructure ◽  
And Topology ◽  
Interaction Of Components ◽  
Physical And Chemical ◽  
Comprehensive Study

The interaction of components in modifying mixtures with the elements of Fe-Mn-С alloys hyperfine structure is investigated. Comprehensive study of the modified material microstructure is conducted. The substructure of Fe-Mn-С alloys is shown to undergo significant changes. The produced castings are characterized with enhanced physical-and-chemical and technological properties

A Critical Review of Existing Hydrogen Diffusion Models Accounting for Different Physical Variables

2014 ◽  
Vol 225 ◽  
pp. 13-18 ◽  
Author(s):  
Jesús Toribio ◽  
Viktor Kharin
Keyword(s):  
Plastic Strain ◽  
Continuum Mechanics ◽  
Critical Review ◽  
Hydrogen Diffusion ◽  
Hydrostatic Stress ◽  
Stress And Strain ◽  
Material Microstructure ◽  
Continuum Modelling ◽  
Physical Variables ◽  
Cumulative Plastic Strain

The present paper offers a continuum modelling of trap-affected hydrogen diffusion in metals and alloys, accounting for different physical variables of both macroscopic nature (i.e., related to continuum mechanics, e.g., stress and strain) and microscopic characteristics (material microstructure, traps, etc.). To this end, the model of hydrogen diffusion assisted by the gradients of both hydrostatic stress and cumulative plastic strain,stress-and-strain assisted hydrogen diffusion, proposed and frequently used by the authors of the present paper (Toribio & Kharin) is analysed in addition to other well-known models such as those proposed by (i) McNabb & Foster, (ii) Oriani, (iii) Leblond & Dubois, (iv) Sofronis & McMeeking, (v) Krom and Bakker, showing their physical and mathematical differences and similarities to account for different physical variables.

Formation and Structure of Work Material in the Friction Stir Forming Process

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Sladjan Lazarevic ◽  
Kenneth A. Ogata ◽  
Scott F. Miller ◽  
Grant H. Kruger ◽  
Blair E. Carlson
Keyword(s):  
Steel Sheet ◽  
Dissimilar Materials ◽  
Mechanical Interlocking ◽  
Forming Process ◽  
Friction Stir ◽  
Joint Structure ◽  
Work Material ◽  
Formation Zone ◽  
Significant Process ◽  
Geometrical Effects

Friction stir forming (FSF) is a new environmentally friendly manufacturing process for lap joining of dissimilar materials. Fundamentally, this process is based on frictionally heating and mechanically stirring work material of the top piece in a plasticized state to form a mechanical interlocking joint within the bottom material. In this research, the significant process parameters were identified and optimized for Al 6014 alloy and mild steel using a design of experiments (DOE) methodology. The overall joint structure and grain microstructure were mapped as the FSF process progressed and the aluminum work material deformed through different stages. It was found that the work material within the joint exhibited two layers, thermomechanical affected zone, which formed due to the contact pressure and angular momentum of the tool, and heat affected formation zone, which was composed of work material formed through the hole in the steel sheet and into the anvil cavity. Two different geometries of anvil design were employed to investigate geometrical effects during FSF of the aluminum. It was found that the direction and amount of work material deformation under the tool varies from the center to the shoulder.

Deep Hole Machining with a Small Diameter Drill and Ultrasonic Vibration

2017 ◽  
Vol 749 ◽  
pp. 107-110
Author(s):  
Yuta Masu ◽  
Tomohito Fukao ◽  
Taiga Yasuki ◽  
Masahiro Hagino ◽  
Takashi Inoue
Keyword(s):  
Surface Roughness ◽  
Ultrasonic Vibration ◽  
Cutting Tool ◽  
Cutting Speed ◽  
Small Diameter ◽  
Maximum Amplitude ◽  
Depth Of Cut ◽  
Deep Hole ◽  
Work Material ◽  
Finished Surface

The method of imparting ultrasonic vibration to the cutting tool is known to improve the shape accuracy and finished surface roughness. However, a uniform evaluation of this function in drilling has not been achieved, and the cutting process cannot be checked from the outside. The aim of this study is to investigate the cutting characteristics in deep hole drilling when an ultrasonic vibrator on the table of a machining center provides vibration with a frequency of 20 kHz to the work piece. The ultrasonic vibrations in this system reach the maximum amplitude in the center of the work material. We evaluated the change in finished surface roughness between the section where drilling starts to the point of maximum amplitude with ultrasonic vibration. The main cutting conditions are as follows: cutting speed (V) 12.6 (mm/min); feed rate (s) 30, 60 (mm/rev); depth of cut (t) = 32 (mm); work material, tool steel; cutting tool material, HSS; point angle (σ) 118 (°); and drill diameter (φ) 4 (mm). Lubricant powder was also added to clarify the cutting effect, and compared the condition in which there was no ultrasonic vibration. The results showed that surface roughness at the point of maximum amplitude was better than that with no vibration.

Modeling Payne effect on basis of linearization of a visco-hyperelastic model

2021 ◽  
Author(s):  
Safia BOUZIDI ◽  
Hocine BECHIR
Keyword(s):  
Characteristic Property ◽  
Nonlinear Viscoelasticity ◽  
Loss Modulus ◽  
Dynamic Strain ◽  
Material Microstructure ◽  
Payne Effect ◽  
Proposed Model ◽  
Storage And Loss Moduli ◽  
Hyperelastic Model ◽  
Complex Young’S Modulus

Abstract The present work concerns the modeling of the Payne effect in nonlinear viscoelasticity. This effect is a characteristic property of filled elastomers. Indeed, under cyclic loading of increasing amplitude, a decrease is shown in the storage modulus and a peak in the loss modulus. In this study, the Payne effect is assumed to arise from a change of the material microstructure, i.e., the thixotropy. The so-called intrinsic time or shift time was inferred from solving a differential equation that represents the evolution of a material's microstructure. Then, the physical time is replaced by the shift time in the framework of a recent fractional visco-hyperelastic model, which was linearized in the neighborhood of a static pre-deformation. As a result, we have investigated the effects of static pre-deformation, frequency, and magnitude of dynamic strain on storage and loss moduli in the steady state. Thereafter, the same set of parameters identified from the complex Young's modulus was used to predict the stress in the pre-deformed configuration. Finally, it is demonstrated that the proposed model is reasonably accurate in predicting Payne effect.

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