Residual Stress Analysis By High Energy Synchrotron Radiation.Ppt

Residual Stress Analysis by Diffraction using

High-Energy Synchrotron Radiation

By ,Aniket Suresh Waghchaure.Michigan Tech University,Houghton.

What is Residual Stress?Definition : Residual Stresses are that remain after the original cause of

the stresses (external forces heat gradient) has been removed. Residual stresses occur for a variety of reasons, including

inelastic deformations and heat treatment. Heat from welding may cause localized expansion, which is

taken up during welding by either the molten metal or the placement of parts being welded.

When the finished weldment cools, some areas cool and contract more than others, leaving residual stresses.

Types of Residual Stresses

I] Macroscopic stresses Long- range in nature, spreads over several grains of the material.

II] Intergranular stresses

Vary over the grain scale.

III] Atomic Scale stresses

Stresses due to coherency at interfaces and dislocation stress fields

Different types of residual stresses.

Figure 1 [1]

Why Residual Stress Analysis? 1) The static loading performance of brittle materials can be improved noticeably

by the intelligent use of residual stress. 2) Compressive residual stress has a beneficial effect on the fatigue life, crack

propagation and stress corrosion of materials whereas tensile residual stress decreases their performance capacity. 3) Residual stress can affect the mechanical behavior of materials causing brittle fracture, fatigue stress and fatigue fracture. 4) The performance of material under thermal, mechanical and other kinds of loading depends on residual stress state.

Residual stress measurement techniques

Residual stresses Destructive Methods

Non Destructive Methods

Hole Drilling Method

Curvature

Method

X ray Diffractio

n

Neutron or

Synchroton

diffraction

Ultrasonics

Magnetic waves

Experimental setup at the high Energy beam line ID 15A at the ESRV,Grenoble,France. [2]

Fig 2.0

Basic Principle Of High Energy Synchrotron Diffraction

Gauge volume and Scanning of the sample

Figure 3 [2] Figure 4 [2]

Gauge volume is given by the intersection of the incoming and the diffracted beam

Formulae's:

d hkl =

Where, dhkl - lattice spacing with hkl denoting Miller’s indexes, θ -Bragg angle ,h -Planck’s constant,c -velocity of light.

=

and are the diffraction elastic constants (DEC).

Gage Volume Dependence

Figure 5 [2] Figure 6 [2]

Applications:

I] Composites (C/SiC-composite): Residual stresses arise due to the shrinkage of the matrix

material and due to the mismatch of the coefficient of thermal expansion (CTE) of the fibers and the matrix

The aim of the HESD analysis was to determine the residual stresses parallel and perpendicular to the fibers within a layer in the bulk of the sample

The penetration depth and the resolution required for experiment cannot be achieved using X-ray or neutron diffraction but can be by employing HESD

Figure 7 Residual stresses parallel and perpendicular to the C fibers in the Sic matrix of a C/Sic-composite. [2]

Results:

a) It was observed by W. reimers, that in the perpendicular direction to the fiber axis, the thermal mismatch is lower and thus the matrix residual stresses become zero in this direction.

b) The average residual stress (Gage volume A) for the two combinations of reflections (6H 110 and 3C 220 resp. 6H 116 and 3C 311) was found to be -30 +/- 40 MPa, while in gage volume B the residual stress in the SiC matrix parallel to the fibers was observed to be 230 +/- 80 MPa.

II] Thermal Barrier Coating : The residual stresses of a duplex thermal barrier coating system consisting of a

plasma sprayed, NiCoCrAlY bond layer with a thickness of 0.15 mm, both deposited on a super alloy in 718 substrate with a thickness of 2 mm (Fig. 9.0), were determined by HESD

Figure 9 Figure 10

Recent research done by ‘Pedro Fernandez’ that hydrostatic M-RS (microscopic residual stress) has following objectives

The investigation of the influence of alloy strength on the matrix RS evolution with deformation.

The evaluation of the reinforcing particles effect (15 vol.% of Al2O3) on the RS evolution.

The assessment of the influence of the loading mode (compressive versus tensile) on the plastic

Recent Research

Strength difference between W2A15A composite and W2A00A alloy is result of ‘Strength Differential Effect(SDE)’

Figure 11 [3]Compressive behavior in T6 condition of 2014Al (W2A00A) and 6061Al (W6A00A)alloys and corresponding composites.

Future ScopeFuture research may be concentrated upon

residual stress analysis and texture analysis of component which is loaded under thermal and mechanical loading .

Dynamic residual stress analysis of thermally loaded components.

SUMMARYHigh-energy synchrotron radiation has been introduced as a

new method which is extensively being used to determine the residual stresses in composites , thermal barrier coating to analyze the residual stresses.

High depth of penetration and high resolution are some advantages of HESD which made it possible to use in variety of applications.

1 .Withers.Bhadeshia, 2001, Overview of Residual Stress Part 1-Measuremnt

Techniques,MST/4640A Vol 17 2. A. Pyzalla ,2000, ‘Methods and Feasibility of Residual Stress Analysis by High-Energy

Synchrotron Radiation in Transmission’ 3. M.E. Fitzpatrick et al,2007, ‘Analysis of Residual Stress by diffraction using Neutron and

Synchrotron Radiation’. 4. Hutchings, et al,’Introduction to the Characterization of Residual Stress by Neutron Diffraction 5. W. Reimers, 18 (1999) , Journal of materials science letters 581-583, ‘The use of high-

energy synchrotron diffraction for residual stress Analyses’ 6. G. Brusch et al, Proceedings of the ICRS 5, Linkrping, Sweden, 1997, pp. 557-562.  7. R. Ostertag et al, in Advanced Structural Inorganic Composites,P. Vincenzini, ed. (Elsevier Science

Publishers, London,New York, 1991), pp. 469-477. 8. W. Reimers et al, ‘Evaluation of Residual Stresses in the Bulk of Materials

by ‘High Energy Synchrotron Diffraction’ 9. Y. M. Chiang et al, Physical Ceramics-Principles for Ceramic

Science and Engineering (John Wiley & Sons, New York, 1997), pp. 26-33. 10. G. Arlt et al. Soc. Am. 37:384 (1965).

References

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