scholarly journals Neutron Diffraction Evaluation of Near Surface Residual Stresses at Welds in 1300 MPa Yield Strength Steel

Materials ◽  
2017 ◽  
Vol 10 (6) ◽  
pp. 593 ◽  
Author(s):  
Ebrahim Harati ◽  
Leif Karlsson ◽  
Lars-Erik Svensson ◽  
Thilo Pirling ◽  
Kamellia Dalaei
Keyword(s):  
Neutron Diffraction ◽  
Yield Strength ◽  
Residual Stresses ◽  
Near Surface ◽  
Surface Residual Stresses

Residual Stress Measurements by Means of Neutron Diffraction

1989 ◽  
Vol 166 ◽  
Author(s):  
H. J. Prask ◽  
C. S. Choi
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Test Specimen ◽  
Hardened Steel ◽  
Fatigue Lifetime ◽  
Near Surface ◽  
Surface Residual Stresses ◽  
Lifetime Test

ABSTRACTEnergy-dispersive neutron diffraction has been developed at the NIST reactor as a probe of sub- and near-surface residual stresses in technological samples. Application of the technique has been made to a variety of metallurgical specimens which includes the determination of tri-axial stresses as a function of depth in a number of uranium-3/4wt%Ti samples with different thermo-mechanical histories, and in two types of 7075-T6 aluminum “ogives”- of interest to the Army. Preliminary results have been obtained for an induction-hardened steel shaft, a fatigue lifetime test specimen for the SAE.

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.

Measurement of Near Surface Residual Stresses Using Electric Discharge Wire Machining

1994 ◽  
Vol 116 (1) ◽  
pp. 1-7 ◽  
Author(s):  
W. Cheng ◽  
I. Finnie ◽  
M. Gremaud ◽  
M. B. Prime
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Electric Discharge ◽  
Theoretical Approach ◽  
Stress Measurement ◽  
Stress Gradient ◽  
Experimental Results ◽  
Residual Stress Measurement ◽  
Near Surface ◽  
Surface Residual Stresses

In previous work it has been shown that near surface residual stresses may be deduced from surface strains produced by making a cut of progressively increasing depth. The process of electric discharge wire machining (EDWM), by providing very narrow cuts, greatly improves the ability of the method to resolve a stress gradient near the surface. However, the EDWM process may also introduce residual stresses. In the present work a model for estimating the influence of EDWM is presented, and a procedure for eliminating its effect on residual stress measurement is developed. Experimental results validate the theoretical approach.

Neutron Diffraction Measurement of Weld Residual Stresses in an UOE Linepipe Subjected to Mechanical Expansion

2013 ◽  
Author(s):  
Shuwen Wen ◽  
Hongbiao Dong ◽  
Shu Yan Zhang ◽  
Adam Bannister ◽  
Martin Connelly
Keyword(s):  
Neutron Diffraction ◽  
Yield Strength ◽  
Residual Stresses ◽  
Parent Material ◽  
Lattice Parameters ◽  
Diffraction Measurement ◽  
Fe Modelling ◽  
Neutron Diffraction Measurement ◽  
Seam Weld ◽  
Expansion Condition

Weld residual stresses in double submerged arc welded (DSAW) UOE linepipes can have significant implications on the integrity and in-service performance of the pipeline from which it is normally constructed, often for deep and ultra-deep water applications. Therefore they have to be considered as a crucial data input for accurate Engineering Critical Assessments (ECAs) of offshore pipelines. This has so far been based on the assumption that the residual stresses in the UOE pipe seam weld are equal to the yield strength of the parent material: an assumption that is likely to cause over-conservatism in conventional pipeline design. In the current study neutron diffraction technique was used to quantify the weld residual stresses of an UOE linepipe (18″ OD × 25.4mm WT, grade X65) in post-expansion condition. The UOE linepipe manufacturing process is briefly introduced first, which involves forming steel plate into pipe, followed by DSAW seam welding and then pipe mechanical expansion. The sample preparation for neutron diffraction measurement of lattice parameters is described next in detail. Neutron diffraction was used to measure the residual elastic strain within the pipe through the precise characterisation of the interplanar crystal lattice spacing and the atomic lattice itself was used as a strain gauge. The measurements were mainly taken in and near the seam weld area of the pipe along the pre-defined lines in through-thickness and cross-weld orientations. The weld residual stresses in three primary directions, namely axial, hoop and radial, were calculated from the measured lattice parameters in as-supplied (welded and expanded) and stress-free conditions using Hooke’s law of linear elasticity, and are systematically presented in the paper. It was found that weld residual stresses of the UOE linepipe in post-expansion condition were significantly lower than the yield strength of the parent material, and in most cases these were less than 50% of the actual yield strength of the parent material. The mechanism of weld residual stress formation and the influence of post-weld expansion on the reduction and through-thickness normalisation of weld residual stresses were studied through finite element (FE) modelling analysis. Finally an example ECA analysis was carried out for the current linepipe under an assumed service loading condition. The degree of over-conservatism that could result by assuming weld residual stresses to be equal to the yield strength of the parent material was demonstrated, as compared to the situation where the values of the required residual stresses were taken from the neutron diffraction measurement. It was therefore shown by the current study that the combined approach of neutron diffraction measurement and FE modelling could greatly enhance the understanding of performance of seam-welded UOE pipes.

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.

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