Residual Stress in SLM Ti6Al4V Alloy Specimens

2015 ◽  
Vol 828-829 ◽  
pp. 305-310 ◽  
Author(s):  
Ina Yadroitsava ◽  
Stephen Grewar ◽  
Daniel Hattingh ◽  
Igor Yadroitsev
Keyword(s):  
Residual Stress ◽  
Laser Scanning ◽  
Complex Geometry ◽  
Ti6al4v Alloy ◽  
Innovative Technology ◽  
Full Density ◽  
X Ray Diffraction ◽  
Surface Residual Stress ◽  
Principal Stresses ◽  
Before And After

Selective Laser Melting (SLM) presents a modern manufacturing process with an innovative technology which allows the production of full-density objects or fine-structured parts with complex geometry and inner structures. Stability and certification of the properties of SLM parts are important tasks for all producers and end-users. One of the drawbacks of this technology is high residual stress in as-made SLM objects. In this study X-ray diffraction technique was used for investigating the residual stress induced into SLM Ti6Al4V alloy samples. Principal stresses were estimated for the cut rectangular specimen. Two types of the cantilevers were produced and numerical simulation of the stress was performed. The bending of cut cantilevers was measured before and after heat treatment. Next series of the samples had rectangular shapes and different thicknesses from 1 to 46 layers. All as-manufactured specimens attached to the substrate showed the presence of tensile residual stresses near the top surface. Residual stress along the laser scanning direction had magnitudes twice that of the stress in the perpendicular direction. Conclusions regarding directions and values of stresses in SLM objects from Ti6Al4V powder are given.

Revision and extension of the standard laboratory technique for X-ray diffraction measurement of residual stress gradients

2007 ◽  
Vol 40 (4) ◽  
pp. 675-683 ◽  
Author(s):  
Cristy L. Azanza Ricardo ◽  
Mirco D'Incau ◽  
Paolo Scardi
Keyword(s):  
Residual Stress ◽  
Hole Drilling ◽  
Al Alloy ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
Surface Residual Stress ◽  
X Ray ◽  
Stress Gradients ◽  
Layer Removal ◽  
Removal Technique

A new procedure is proposed to determine sub-surface residual stress gradients by laboratory X-ray diffraction measurements at different depths using a chemical layer-removal technique. The standard correction algorithm for stress relaxation due to layer removal is improved by including corrections for X-ray absorption, and by the addition of constraints imposed by the mechanical equilibrium conditions. Besides correcting the data,i.e.providing more reliable through-thickness residual stress trends, the proposed procedure also provides an elastically compatible and plausible estimate of the residual stress inside the component, well beyond the measured region. The application of the model is illustrated for a set of Al-alloy components shot-peened at different Almen intensities. Results are compared with those given by `blind hole drilling', which is an independent and partly destructive method.

Crystallite size and microstrain: XRD line broadening analysis of AgSiN thin films

2019 ◽  
Vol 48 (6) ◽  
pp. 473-480 ◽  
Author(s):  
Umi Zalilah Mohamad Zaidi ◽  
A.R. Bushroa ◽  
Reza Rahbari Ghahnavyeh ◽  
Reza Mahmoodian
Keyword(s):  
Thin Films ◽  
Residual Stress ◽  
Magnetron Sputtering ◽  
Crystallite Size ◽  
Approximation Method ◽  
Ti6al4v Alloy ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
Content Type ◽  
Three Samples

Purpose This paper aims to determine the crystallite size and microstrain values of AgSiN thin films using potential approach called approximation method. This method can be used as a replacement for other determination methods such as Williamson-Hall (W-H) plot and Warren-Averbach analysis. Design/methodology/approach The monolayer AgSiN thin films on Ti6Al4V alloy were fabricated using magnetron sputtering technique. To evaluate the crystallite size and microstrain values, the thin films were deposited under different bias voltage (−75, −150 and −200 V). X-ray diffraction (XRD) broadening profile along with approximation method were used to determine the crystallite size and microstrain values. The reliability of the method was proved by comparing it with scanning electron microscopy graph and W-H plot method. The second parameters’ microstrain obtained was used to project the residual stress present in the thin films. Further discussion on the thin films was done by relating the residual stress with the adhesion strength and the thickness of the films. Findings XRD-approximation method results revealed that the crystallite size values obtained from the method were in a good agreement when it is compared with Scherer formula and W-H method. Meanwhile, the calculations for thin films corresponding residual stresses were correlated well with scratch adhesion critical loads with the lowest residual stress was noted for sample with lowest microstrain and has thickest thickness among the three samples. Practical implications The fabricated thin films were intended to be used in antibacterial applications. Originality/value Up to the knowledge from literature review, there are no reports on depositing AgSiN on Ti6Al4V alloy via magnetron sputtering to elucidate the crystallite size and microstrain properties using the approximation method.

Effect of Milling Speed and Feed on Surface Residual Stress of 7050-T7451 Aluminum Alloy

2012 ◽  
Vol 499 ◽  
pp. 217-222 ◽  
Author(s):  
C. Li ◽  
Yi Wan ◽  
R.R. Zhang ◽  
Zhan Qiang Liu
Keyword(s):  
Residual Stress ◽  
Aluminum Alloy ◽  
Cutting Speed ◽  
Diffraction Method ◽  
Cutting Condition ◽  
Feed Speed ◽  
X Ray Diffraction ◽  
Surface Residual Stress ◽  
Orthogonal Direction ◽  
Machined Surface

The residual stress in the milling of 7050-T7451 aluminum alloy was measured using X-ray diffraction method in which Psi-oscillation, Phi-oscillation and peak fit were adopted. Cutting speed and feed are main variables which were considered in this study. The results show that compressive residual stresses are generated in surface for the down milling generally, which is mainly due to burnishing effect between the tools flank face and the machined surface. In feed and its orthogonal direction, the effect of cutting speed and feed speed on residual stress is similar. Therefore, required residual stress can be achieved by controlling the cutting condition such as cutting speed, feed speed etc.

Fatigue Life Variance Prediction Incorporating Residual Stress Scatter Induced by Super-Finishing Grinding Process

2009 ◽  
Vol 416 ◽  
pp. 45-50
Author(s):  
Guang Hui Lu ◽  
Xue Ping Zhang ◽  
Er Wei Gao
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Diffraction Method ◽  
Machining Process ◽  
Stress Distributions ◽  
X Ray Diffraction ◽  
Machining Processes ◽  
Surface Residual Stress ◽  
Bearing Rings ◽  
The Impact

It is well known that there is a lager deviation in the fatigue life of machined components even under nominally identical loading conditions. Understanding and controlling fatigue life variance are essential to enhance reliability. However, few research focus on the impact of machining processes on the fatigue life variance of machined components. In this study, surface residual stress distributions of bearing rings randomly selected from a production line by super-finishing grinding, are measured by X-ray diffraction method in cutting and feed direction, and its scatter is analyzed by statistical tools. Based on the variance prediction theories, build a simplified fatigue life variance prediction model incorporating the resultant residual stresses scatter induced by machining process. Based on the Basquin equation, the model is validated by experimental data published in literature. The predicted fatigue life agrees well with the experimental average fatigue life. Statistical analysis shows that the predicted variances of fatigue life are equal to those estimated from experimental fatigue life.

Non-destructive Surface Residual Stress Profiling by Multireflection Grazing Incidence X-Ray Diffraction: a 7050 Al Alloy Study

2020 ◽  
Vol 60 (4) ◽  
pp. 475-480
Author(s):  
V. A. N. Righetti ◽  
T. M. B. Campos ◽  
L. B. Robatto ◽  
R. R. Rego ◽  
G. P. Thim
Keyword(s):  
Residual Stress ◽  
Grazing Incidence ◽  
Al Alloy ◽  
X Ray Diffraction ◽  
Surface Residual Stress ◽  
X Ray ◽  
Non Destructive

Wear and Surface Residual Stress Evolution on Twin-Disc Tests of Rail/Wheel Steels

2013 ◽  
Vol 768-769 ◽  
pp. 707-713
Author(s):  
António Castanhola Batista ◽  
Daniel F.C. Peixoto ◽  
Joao P. Nobre ◽  
Luís Coelho ◽  
Diogo Mesquita Ramos ◽  
...  
Keyword(s):  
Residual Stress ◽  
Fatigue Behavior ◽  
Contact Fatigue ◽  
Major Influence ◽  
Stress Evolution ◽  
X Ray Diffraction ◽  
Surface Layers ◽  
Surface Residual Stress ◽  
X Ray ◽  
Initiation And Propagation

Twin disc tribological tests were performed in wheel and rail materials, with specimens taken from a Spanish AVE train wheel and a UIC60 rail, in a program intended to characterize their contact fatigue behavior. The X-ray diffraction technique was used to characterize the residual stress distribution at the initial and damaged stages, as well as in intermediate stages, since existing residual stresses in the surface layers of the railways steels and its evolution during contact loading can have a major influence on crack initiation and propagation.

Effects of Residual Stresses on the High Cycle Fatigue Behavior of Ti-6Al-4V

2010 ◽  
Author(s):  
Yu-Jia Li ◽  
Fu-Zhen Xuan ◽  
Zheng-Dong Wang ◽  
Shan-Tung Tu
Keyword(s):  
Residual Stress ◽  
Fatigue Limit ◽  
Stress Ratio ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
X Ray Diffraction ◽  
Surface Residual Stress ◽  
Manufacturing Techniques ◽  
Stress Ratios ◽  
Effect Of Surface

Axial force-controlled fatigue tests are conducted at various stress ratios (R) on Ti-6Al-4V specimens prepared by two different manufacturing techniques (hard turning plus polishing with and without vacuum stress relieve anneal carried out after polishing). Residual stress is measured by using X-ray diffraction. Results indicate that the surface compressive residual stress lead to an increase of fatigue limit at a given life and stress ratio. This effect decreases with increasing stress ratio R. At R = 0.6, the effect of surface residual stress on fatigue limit fades away. In addition, the location of crack initiation shifts from surface to interior when the stress ratio changes from −1 to 0.6.

X-Ray Diffraction Study of the Effects of Uniaxial Plastic Deformation on Residual Stress Measurements

1968 ◽  
Vol 12 ◽  
pp. 269-300 ◽  
Author(s):  
A. L. Esquivel
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Diffraction Study ◽  
Stress Factors ◽  
X Ray Diffraction ◽  
Test Fixture ◽  
X Ray ◽  
Stress Measurements ◽  
Iron Aluminum ◽  
Before And After

AbstractUniaxial Plastic Deformation (UPD) has been known to produce anomalies in residual stress measurements based on x-ray diffraction techniques. This study was undertaken to determine the magnitude of the effects, if any, on residual stress calculations from various materials subjected to UPD. An x-ray diffraction study using the two-exposure method ( ψ = 0° and ψ = U5°) was made on several iron, aluminum, and titanium alloys (AISI 4340, 4330M, 4130; 2024-13, 7075-T611; Ti-6Al-4V) before and after these alloys were deformed plastically by bending on a U-bend test fixture. The x-ray peak shifts, Δ2θ0-ψ, were recorded and the x-ray stress factors, Ki, calculated by three different methods. The results indicate that UPD of the calibration specimens will increase or decrease Ki depending on the alloy. These results are discussed together with observations on the additivity of residual and applied stresses, and the per cent differences in the stress measurements based on stress factors calculated by three different methods.

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