Drawability of Ti-6Al-4V Sheet at Elevated Temperatures

2010 ◽  
Vol 654-656 ◽  
pp. 902-905 ◽  
Author(s):  
Nho Kwang Park ◽  
Jin Gee Park ◽  
Sang Hyun Seo ◽  
Jeoung Han Kim
Keyword(s):  
Residual Stresses ◽  
Slip System ◽  
Process Parameters ◽  
Elevated Temperatures ◽  
Plastic Anisotropy ◽  
Drawing Ratio ◽  
Limit Drawing Ratio ◽  
Blank Holding Force ◽  
Forming Temperature ◽  
Increasing Temperature

Titanium and its alloys are difficult-to-form materials due to limited slip system and plastic anisotropy. Titanium is also prone to change in color due to oxidation at high temperatures. It is thus advisable to conduct deep drawing of titanium and its alloys at temperatures below 600°C. In this study, the drawability of Ti-6Al-4V sheet is evaluated in respect to the process parameters such as forming temperature, forming speed, and blank holding force at elevated temperatures. It is shown that the limit drawing ratio (LDR) increases with increasing temperature, but varies insignificantly with forming speed. The development of residual stresses in the wall of drawn cups during deformation was evaluated.

Effect of Coating Process Parameters on the Development of Residual Stresses in Ceramic Coatings

2019 ◽  
Author(s):  
Ali Gadelmoula ◽  
Khaled Al-Athel
Keyword(s):  
Residual Stresses ◽  
Process Parameters ◽  
Elevated Temperatures ◽  
Ceramic Coatings ◽  
Interface Roughness ◽  
Fe Model ◽  
Computational Framework ◽  
Scientists And Engineers ◽  
Coating Layers

Abstract Ceramic coatings are widely used in many engineering applications, especially applications related to components operating at elevated temperatures. One of the main issues relates to ceramic coatings is the development of residual stresses due to quenching and the thermal mismatch between the deposited coating layers and the substrate. In this work, a computational framework is developed to investigate the effect of various process parameters on the development of the residual stresses. The geometry of the coating layers and the interface roughness between the layers is first generated using SimCoat, a Monte Carlo based statistical algorithm that determines the effect of process parameters (droplet size, spraying speed, etc.) on the characteristics of the developed coating (coating thickness, porosity, etc.). An in-house code is used to convert the statistical data into a finite element (FE) model. Various FE models are generated with different process parameters, and the development of residual stresses is compared between them. The developed framework can be used by material scientists and engineers to predict the quality of the coating and optimize the process parameters to any specific application.

An Analytical Method for Prediction of Limiting Drawing Ratio For Redrawing Stages of Axisymmetric Deep Drawn Components

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Ali Fazli ◽  
Behrooz Arezoo
Keyword(s):  
Process Parameters ◽  
Analytical Method ◽  
Plastic Anisotropy ◽  
Numerical Results ◽  
Analytical Determination ◽  
Strain Hardening Exponent ◽  
Anisotropy Ratio ◽  
Drawing Ratio ◽  
Intermediate Annealing ◽  
Limiting Drawing Ratio

In this paper, an analytical method for estimating the limiting drawing ratio (LDR) of the redrawing stages in deep drawing process of axisymmetric components is represented. In this method, the effects of parameters of blankholder arc, die arc, and punch arc region are taken into account for the analytical determination of LDR. The presented method can predict the limiting drawing ratio for redrawing with/without intermediate annealing processes. The results are compared to numerical results and experimental results reported in the literature and also industrial results reported in handbooks. It is shown that the presented method is in good agreement with the experimental and numerical results. Using the presented method, the effect of some process parameters on the LDR is investigated. It is shown that process parameters such as, coefficient of friction, strain hardening exponent, normal plastic anisotropy ratio, ratio of die arc radius to blank thickness and ratio of blank thickness to diameter has significant effect on the LDR. The effect of intermediate annealing process is also examined.

Fiber Push-Out Testing of Intermetallic Matrix Composites at Elevated Temperatures

1992 ◽  
Vol 273 ◽  
Author(s):  
Jeffrey I. Eldridge
Keyword(s):  
Residual Stresses ◽  
Metal Matrix Composites ◽  
Metal Matrix ◽  
Elevated Temperatures ◽  
Matrix Composites ◽  
Fiber Reinforced ◽  
Intermetallic Matrix ◽  
Intermetallic Matrix Composites ◽  
Increasing Temperature ◽  
Push Out

ABSTRACTA newly developed apparatus for performing fiber push-out testing at elevated temperatures has been applied towards testing fiber-reinforced intermetallic and metal matrix composites. This new capability shows the effects of the relief of residual stresses and increased matrix ductility with increasing temperature on fiber debonding and sliding behavior.

scholarly journals Investigation of process parameters and plate local thickening on residual stresses in hot stamping process

2021 ◽  
Vol 22 ◽  
pp. 18
Author(s):  
Jinbo Li ◽  
Xiaohui Chen ◽  
Xianlong Liu
Keyword(s):  
Aluminum Alloy ◽  
Residual Stresses ◽  
Process Parameters ◽  
Hot Stamping ◽  
Experimental Methods ◽  
Small Radius ◽  
Blank Holder Force ◽  
Flat Plates ◽  
Blank Holder ◽  
Forming Temperature

In this paper, local-thickened plates are adopted for aluminum alloy square cups stamping with relatively low values of residual stresses and small radius at the bottom corner. By utilizing numerical and experimental methods, the effects of process parameters and plate local thickening on the residual stress distribution of hot stamped aluminum alloy square cups are studied. Furthermore, the influence of plate local thickening on the radius of bottom corner of square cups is also investigated. The results showed that with an increase in the forming temperature, blank holder force and die corner radius, residual stresses in hot stamped square cups can be reduced. The same effect can be achieved by decreasing the die entrance radius. As opposed to the flat plates, using local-thickened plates can not only reduce the residual stresses values in hot stamped square cups, but also decrease the radius at the bottom corner of square cups. When the optimized thickening scheme of plate is used, the smaller radius at the bottom corner, the lower residual stresses in the square cups are obtained.

The Influence of Process Parameters during Hot Stamping of AA6111 Aluminum Alloy Sheet

2012 ◽  
Vol 572 ◽  
pp. 255-260 ◽  
Author(s):  
Qing Lei Meng ◽  
Bao Yu Wang ◽  
Lei Fu ◽  
Jing Zhou ◽  
Jian Guo Lin
Keyword(s):  
Numerical Simulation ◽  
Aluminum Alloy ◽  
Process Parameters ◽  
Hot Stamping ◽  
Alloy Sheet ◽  
Aluminum Alloy Sheet ◽  
Influence Of Process Parameters ◽  
Blank Holding Force ◽  
Forming Temperature ◽  
Forming Defects

The AA6111 aluminum alloy sheet is widely used in auto-body manufacture. It can make use of good plasticity under high temperature to form more complex parts by using the hot stamping. The influence of process parameters in hot stamping of AA6111 aluminum alloy sheet is investigated through numerical simulation in this paper, including blank holding force (BHF), friction coefficient, stamping velocity and initial forming temperature. Finally forming defects of numerical simulation are verified through the hot stamping experiments. The results show that it can effectively avoid wrinkling and fracture by controlling the BHF, good lubricant is in favor of forming and numerical simulation can accurately predict forming defects to guide the production.

Theoretical study of the prestressing strand's stress by computer modeling methods

2020 ◽  
Vol 76 (11) ◽  
pp. 1139-1148
Author(s):  
A. G. Korchunov ◽  
E. M. Medvedeva ◽  
E. M. Golubchik
Keyword(s):  
Residual Stresses ◽  
High Strength ◽  
Pearlitic Steel ◽  
Internal Stresses ◽  
Steel Microstructure ◽  
Compressive Stresses ◽  
Wide Range ◽  
Prestressing Strands ◽  
Increasing Temperature ◽  
Wire Strand

The modern construction industry widely uses reinforced concrete structures, where high-strength prestressing strands are used. Key parameters determining strength and relaxation resistance are a steel microstructure and internal stresses. The aim of the work was a computer research of a stage-by-stage formation of internal stresses during production of prestressing strands of structure 1х7(1+6), 12.5 mm diameter, 1770 MPa strength grade, made of pearlitic steel, as well as study of various modes of mechanical and thermal treatment (MTT) influence on their distribution. To study the effect of every strand manufacturing operation on internal stresses of its wires, the authors developed three models: stranding and reducing a 7-wire strand; straightening of a laid strand, stranding and MTT of a 7-wire strand. It was shown that absolute values of residual stresses and their distribution in a wire used for strands of a specified structure significantly influence performance properties of strands. The use of MTT makes it possible to control in a wide range a redistribution of residual stresses in steel resulting from drawing and strand laying processes. It was established that during drawing of up to 80% degree, compressive stresses of 1100-1200 MPa degree are generated in the central layers of wire. The residual stresses on the wire surface accounted for 450-500 MPa and were tension in nature. The tension within a range of 70 kN to 82 kN combined with a temperature range of 360-380°С contributes to a two-fold decrease in residual stresses both in the central and surface layers of wire. When increasing temperature up to 400°С and maintaining the tension, it is possible to achieve maximum balance of residual stresses. Stranding stresses, whose high values entail failure of lay length and geometry of the studied strand may be fully eliminated only at tension of 82 kN and temperature of 400°С. Otherwise, stranding stresses result in opening of strands.

scholarly journals Comparison of Phase Characteristics and Residual Stresses in Ti-6Al-4V Alloy Manufactured by Laser Powder Bed Fusion (L-PBF) and Electron Beam Powder Bed Fusion (EB-PBF) Techniques

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 796
Author(s):  
Aya Takase ◽  
Takuya Ishimoto ◽  
Naotaka Morita ◽  
Naoko Ikeo ◽  
Takayoshi Nakano
Keyword(s):  
Electron Beam ◽  
Residual Stresses ◽  
Cooling Rate ◽  
Process Parameters ◽  
Phase Evolution ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Solidification Temperature ◽  
Powder Bed ◽  
Β Phase

Ti-6Al-4V alloy fabricated by laser powder bed fusion (L-PBF) and electron beam powder bed fusion (EB-PBF) techniques have been studied for applications ranging from medicine to aviation. The fabrication technique is often selected based on the part size and fabrication speed, while less attention is paid to the differences in the physicochemical properties. Especially, the relationship between the evolution of α, α’, and β phases in as-grown parts and the fabrication techniques is unclear. This work systematically and quantitatively investigates how L-PBF and EB-PBF and their process parameters affect the phase evolution of Ti-6Al-4V and residual stresses in the final parts. This is the first report demonstrating the correlations among measured parameters, indicating the lattice strain reduces, and c/a increases, shifting from an α’ to α+β or α structure as the crystallite size of the α or α’ phase increases. The experimental results combined with heat-transfer simulation indicate the cooling rate near the β transus temperature dictates the resulting phase characteristics, whereas the residual stress depends on the cooling rate immediately below the solidification temperature. This study provides new insights into the previously unknown differences in the α, α’, and β phase evolution between L-PBF and EB-PBF and their process parameters.

scholarly journals The influence of freeform bending process parameters on residual stresses for steel tubes

2021 ◽  
pp. 100047
Author(s):  
Daniel Maier ◽  
Sophie Stebner ◽  
Ahmed Ismail ◽  
Michael Dölz ◽  
Boris Lohmann ◽  
...  
Keyword(s):  
Residual Stresses ◽  
Process Parameters ◽  
Steel Tubes ◽  
Bending Process

scholarly journals Influence of High-Productivity Process Parameters on the Surface Quality and Residual Stress State of AISI 316L Components Produced by Directed Energy Deposition

2021 ◽  
Author(s):  
Gabriele Piscopo ◽  
Alessandro Salmi ◽  
Eleonora Atzeni
Keyword(s):  
Surface Roughness ◽  
Residual Stresses ◽  
Surface Quality ◽  
Process Parameters ◽  
Energy Deposition ◽  
Industrial Applications ◽  
High Productivity ◽  
Directed Energy Deposition ◽  
Productivity Process ◽  
Directed Energy

AbstractThe production of large components is one of the most powerful applications of laser powder-directed energy deposition (LP-DED) processes. High productivity could be achieved, when focusing on industrial applications, by selecting the proper process parameters. However, it is of crucial importance to understand the strategies that are necessary to increase productivity while maintaining the overall part quality and minimizing the need for post-processing. In this paper, an analysis of the dimensional deviations, surface roughness and subsurface residual stresses of samples produced by LP-DED is described as a function of the applied energy input. The aim of this work is to analyze the effects of high-productivity process parameters on the surface quality and the mechanical characteristics of the samples. The obtained results show that the analyzed process parameters affect the dimensional deviations and the residual stresses, but have a very little influence on surface roughness, which is instead dominated by the presence of unmelted particles.

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.

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