X-ray Measurements of Surface Residual Stresses in Cold Rolled α-Brass

1970 ◽  
Vol 14 ◽  
pp. 389-407 ◽  
Author(s):  
W. Wallace ◽  
T. Terada
Keyword(s):  
Residual Stresses ◽  
Lattice Parameter ◽  
Rolled Sheet ◽  
Near Surface ◽  
X Ray ◽  
Elastic Stresses ◽  
Surface Residual Stresses ◽  
Exposure Method ◽  
Cold Rolled ◽  
Anisotropic Elastic

AbstractResidual elastic stresses have been measured in cold rolled α-brass (30% zinc) using the available x-ray diffractometer methods. Residual stress values obtained by the two exposure and sin2ψ methods of stress analysis are compared with data obtained using Wagner's extrapolation method.For deformations up to 50% reduction in thickness, tensile surface stresses prevailed, and in most cases could be detected by these methods. Uncertainty of the value of a0, the lattice parameter of the deformed' material, presents a serious limitation to the extrapolation technique. Using the approximation a0 = a0ann, residual stresses appear lower than, and frequently of opposite sign to those given by the two exposure method. In addition, lattice parameter variations in the near surface regions of the rolled sheet were opposite to those expected from the true macrostress distributions shown to exist by the two exposure method and by strain gauge techniques. The distributions of ahkl points in the extrapolation plots were in agreement with theory for a combination of anisotropic elastic stresses and low stacking fault density.

The Compliance Method for Measurement of Near Surface Residual Stresses—Application and Validation for Surface Treatment by Laser and Shot-Peening

1994 ◽  
Vol 116 (4) ◽  
pp. 556-560 ◽  
Author(s):  
W. Cheng ◽  
I. Finnie ◽  
M. Gremaud ◽  
A. Rosselet ◽  
R. D. Streit
Keyword(s):  
Residual Stresses ◽  
Surface Treatment ◽  
Hole Drilling ◽  
Ray Method ◽  
Near Surface ◽  
X Ray ◽  
Advantages And Disadvantages ◽  
Surface Residual Stresses ◽  
Ray Methods ◽  
Good Agreement

Residual stresses due to surface treatment are measured using the compliance method. The method makes use of the strains measured on the surface while a cut is extended progressively along a plane of interest. The experimental results for a shot peened specimen show good agreement with those obtained by the X-ray method. This experiment demonstrates that the compliance method is accurate and capable of measuring residual stresses which vary rapidly over a depth of less than 50 μm. Good general agreement with results by the X-ray method is also obtained for a laser treated specimen. Some advantages and disadvantages of the present method relative to hole-drilling, layer removal and X-ray methods are discussed.

Micro-slotting technique for reliable measurement of sub-surface residual stress in Ti-6Al-4V

2018 ◽  
Vol 53 (6) ◽  
pp. 389-399 ◽  
Author(s):  
Elizabeth Burns ◽  
Joseph Newkirk ◽  
James Castle
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Image Correlation ◽  
X Ray Diffraction ◽  
Surface Residual Stress ◽  
Near Surface ◽  
X Ray ◽  
Measurement Volume ◽  
Surface Residual Stresses

Micro-slotting, a relaxation residual stress measurement technique, has recently been shown to be an effective method for measuring local residual stresses in a variety of materials. The micro-slotting method relies on a scanning electron microscope–focused ion beam system for milling and imaging, digital image correlation software to track displacements due to residual stress relaxation after milling, and finite element analysis for displacement–stress correlation and calculation of the original stress state in the imaged region. The high spatial resolution of the micro-slotting method makes it a promising technique for obtaining near-surface residual stress data in Ti-6Al-4V components for input into fatigue life models and crack growth simulations. However, use of the micro-slotting method on this alloy has yet to be evaluated against more established measurement techniques. In this study, spatially resolved sub-surface residual stress measurements were obtained on shot peened and low-stress surface-machined Ti-6Al-4V planar coupons using the micro-slotting method and were compared to measurements obtained using the conventional X-ray diffraction depth profiling technique. The sub-surface measurements were in good agreement for the shot peened sample. Observed differences in the measured near-surface residual stresses on the surface-machined sample were attributed to the larger measurement volume of the X-ray diffraction method, suggesting that the micron-sized measurement volume of the micro-slotting method may be more suitable for capturing shallow stress profiles and steep stress gradients. Prior to performing the micro-slotting measurements, finite element modeled displacements were used to verify the measurement procedure and to address uncertainties in the milled slot geometries. The results of this study demonstrated the validity of the micro-slotting procedure and established the technique as a reliable method for measuring sub-surface residual stresses in Ti-6Al-4V.

The Compliance Method for Measurement of Near Surface Residual Stresses—Analytical Background

1994 ◽  
Vol 116 (4) ◽  
pp. 550-555 ◽  
Author(s):  
M. Gremaud ◽  
W. Cheng ◽  
I. Finnie ◽  
M. B. Prime
Keyword(s):  
Numerical Simulation ◽  
Residual Stresses ◽  
Random Errors ◽  
Residual Stress Field ◽  
Near Surface ◽  
Surface Residual Stresses ◽  
Zero Shift ◽  
Stress States ◽  
The Stability ◽  
Piecewise Functions

Introducing a thin cut from the surface of a part containing residual stresses produces a change in strain on the surface. When the strains are measured as a function of the depth of the cut, residual stresses near the surface can be estimated using the compliance method. In previous work, the unknown residual stress field was represented by a series of continuous polynomials. The present paper shows that for stress states with steep gradients, superior predictions are obtained by using “overlapping piecewise functions” to represent the stresses. The stability of the method under the influence of random errors and a zero shift is demonstrated by numerical simulation.

Neutron and X-Ray Diffraction Analysis of Residual Stresses in Cold-Rolled Pearlitic Steel Sheet

2006 ◽  
pp. 375-380
Author(s):  
Marc Seefeldt ◽  
Artur Walentek ◽  
Paul Van Houtte ◽  
Miroslav Vrána ◽  
Petr Lukáš
Keyword(s):  
Residual Stresses ◽  
Diffraction Analysis ◽  
Steel Sheet ◽  
Pearlitic Steel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cold Rolled

Residual Stresses and Differential Deformation of Electroplated Structures

1989 ◽  
Vol 33 ◽  
pp. 161-169
Author(s):  
G. Sheikh ◽  
I. C. Noyan
Keyword(s):  
Residual Stresses ◽  
Lattice Parameter ◽  
Stress Profile ◽  
X Ray ◽  
Residual Stress Profile ◽  
Cyclic Loading And Unloading ◽  
Nickel Substrates ◽  
Loading And Unloading

AbstractWe report the results of a recent study where nickel substrates electroplated with chromium were loaded in-situ on an x-ray diffractometer. This technique allows determination of lattice spacings in the vicinity of the interface for both the film and the substrate as a function of the applied load. We used such lattice parameter data, SEM observations of the surface and x-ray peak breadth data to study the partitioning of deformation between the film and the substrate. The data indicates progressive loss of adhesion between the film and the substrate with increasing deformation. We observe significant effect of electroplating residual stresses on the mechanical behavior of the system. The loss of adhesion between the film and the substrate coupled with the initial residual stress profile causes an apparent 'negative Poisson's ratio' for the film during initial stages of the loading. This effect disappears with cyclic loading and unloading.

Residual Stresses Resulting from the Forming of High Strength Aluminium Alloys

1959 ◽  
Vol 63 (578) ◽  
pp. 90-94
Author(s):  
G. A. Hawkes
Keyword(s):  
Heat Treatment ◽  
Residual Stresses ◽  
Residual Strain ◽  
Aluminium Alloys ◽  
Solution Treatment ◽  
High Strength ◽  
Hot Forming ◽  
X Ray ◽  
Back Reflection ◽  
Surface Residual Stresses

Summary:An X-ray back reflection technique has been used to measure the surface residual stresses resulting from the cold and hot forming of certain high strength aluminium alloys. The alloys examined were to specifications DTD 683, DTD 687 and B.S.S. L65, and the residual stresses have been related to the residual strain in bending of these alloys. The results show that, apart from the degree of straining, the residual stresses are affected by the heat treatment (cold or hot quench) and the amount (if any) of controlled stretching that the alloy has had between solution treatment and precipitation.

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