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.

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.

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

Determination of surface residual stresses in carburised AISI 8620 steel by the magnetic Barkhausen noise method

2020 ◽  
Vol 62 (7) ◽  
pp. 416-421
Author(s):  
T Kaleli ◽  
C Hakan Gür
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Stress Measurement ◽  
Fatigue Behaviour ◽  
Barkhausen Noise ◽  
Magnetic Barkhausen Noise ◽  
Surface Residual Stress ◽  
Technical Requirements ◽  
Surface Residual Stresses

Management of the residual stress state is vital for the design and production stages of carburised components in order to satisfy the technical requirements related to performance, fatigue behaviour and useful lifetime. This enforces the use of practical, reliable and time- and cost-effective stress measurement methods by manufacturers. This study aims to investigate the efficiency of the magnetic Barkhausen noise (MBN) method in rapid non-destructive determination of surface residual stresses in carburised steels. A series of AISI 8620 steel specimens with different residual stress states was prepared by altering the carburising and subsequent tempering parameters. The specimens were characterised through scanning electron microscopy (SEM) investigations and hardness measurements, and the surface residual stresses were determined using both the MBN and X-ray diffraction (XRD) methods. The results show that a good correlation exists between surface residual stress and the parameters derived from the MBN signals.

Simulation of Quenching in Aluminium and Comparison With Neutron Diffraction Measurements

2008 ◽  
Author(s):  
R. J. Dennis ◽  
S. Phillips ◽  
C. E. Truman ◽  
A. Stiles ◽  
R. Plant
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Finite Element ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Finite Element Methods ◽  
Test Specimen ◽  
Internal Diameter ◽  
Linear Finite Element ◽  
Quenching Process

The through life integrity of engineering components are routinely assessed using complex finite element methods. A critical input to such an assessment is an understanding of the operating environment, including service loading and temperature. Significant effort is expended identifying and understanding the effect of service loads on component integrity however there are many cases where service loading in isolation cannot account for premature failure of components during testing or in-service. A key assumption is that components in the as-built condition are often treated as stress and defect free and of nominal dimensions. This approach can however be inadequate and there are many documented cases where residual stress has influenced the in-service integrity of components. In this paper the magnitude and distribution of residual stresses are investigated in a quenched Aluminium 2014A TB test specimen. The test specimen has been specifically designed to contain design features representative of pressurised aerospace components which are quenched during manufacture. The specimen has two sections, one cylindrical (65mm internal diameter) and one oval (125mm largest internal diameter). The outer wall thickness is 10mm and the overall specimen length is 200mm with the two sections joined by a 30mm bridge section. The specimen has been subject to solution heat treatment at 505°C for five hours. Following heat treatment the specimen is rapidly quenched in cold water at 10°C with the cylindrical end entering the water first. Non-linear finite element methods have been developed to simulate the quenching process making use of user defined subroutines to enhance the standard features available in the finite element code. The accuracy of the predicted residual stresses has been assessed by comparison with neutron diffraction measurements at a range of critical locations. The work provides an extremely useful insight into how non-linear finite element methods can be successfully used to predict the residual stresses that are generated as a result of the quenching process. Where residual stresses are a potential integrity concern an understanding of the magnitude and spatial distribution of residual stress can be used to influence both the design and in-service operation of components.

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.

A Critical Examination of Sachs’ Material-Removal Method for Determination of Residual Stress

2003 ◽  
Author(s):  
Anthony P. Parker
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Critical Examination ◽  
Fatigue Lifetime ◽  
Experimental Procedure ◽  
Linear Elastic ◽  
Order Of Magnitude ◽  
Hoop Stresses ◽  
Elastic Unloading

Sachs’ method is an experimental procedure used primarily in the determination of residual stresses in autofrettaged thick cylinders. In its usual form it involves fixing axial and hoop direction strain gauges to the OD of a tube; strain readings are then obtained after each incremental removal of material from the bore. Sachs’ analysis assumes that the remaining tube unloads in linear-elastic fashion throughout the process and that superposition may therefore be employed to quantify the residual stresses within the original tube. By numerical simulation of two complete Sachs’ experimental sequences with ‘open end’ conditions it is demonstrated that the assumption of elastic unloading is invalidated by the Bauschinger effect. Sachs’ method thereby overestimates compressive residual bore hoop stresses in a typical tube by between 24% and 43%. If used as the basis for cyclic pressurization fatigue lifetime predictions with pre-existing cracks, such discrepancies will cause overestimates in fatigue lifetime of an order of magnitude. Sachs’ experimental procedure is therefore not recommended as a reliable or conservative method for determination of residual stress.

Determination of Residual Stresses Induced by Hardened Steel Turning Using Finite Element Methods

1995 ◽  
Author(s):  
Guang Yang ◽  
Caroline Norma Jane Tite ◽  
Graham Thomas Smith ◽  
Anthony David Hope ◽  
Siamak Noroozi
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Experimental Determination ◽  
Surface Region ◽  
Hardened Steel ◽  
Qualitative Assessment ◽  
Machined Surface ◽  
Steel Turning

Abstract A method of using the finite element mode to predict the residual stresses on the surface of machined hardened steel is proposed. The proposed model is based on the analysis of strain relaxation data obtained from the measurement of residual stresses by material removal methods involving two stages; 1). experimental determination of the thermal residual stresses produced during heat treatment 2). experimental determination of the resultant residual stress on the machined surface due to the interaction between thermal stress relief and the machining stresses induced. The proposed finite element model was used to determine the relationship between the two types of residual stress within the machined surface region of a workpiece. It was found that the remaining residual stresses are determined mainly by stress release rather than induction. Such a finite element approach aims at an improvement in accuracy and reduction in the number of experiments required to determine the nature of residual stresses. Furthermore, it could provide an improved qualitative assessment of residual stresses when applied to hardened steel turning.

Residual Stresses Distribution Measured by Neutron Diffraction in Fabricated Square High Strength Steel Tubes

2014 ◽  
Vol 777 ◽  
pp. 249-254 ◽  
Author(s):  
Fidelis R. Mashiri ◽  
Anna M. Paradowska ◽  
Brian Uy ◽  
Zhong Tao ◽  
Mahbub Khan ◽  
...  
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
High Strength Steel ◽  
Local Buckling ◽  
High Strength ◽  
Civil Engineering Infrastructure ◽  
Stress Line ◽  
Stub Columns

Engineers are increasingly encouraged to consider sustainability in the design and construction of new civil engineering infrastructure. Sustainability can be achieved through the use of high strength materials thereby reducing quantity of materials required in construction where possible. Knowledge of residual stresses in fabricated columns is important in identifying whether the fabricated columns can be classified as heavily welded (HW) or lightly welded (LW). The determination of residual stresses can be used to determine the local buckling of stub columns. Residual stress magnitudes are also essential in the numerical modelling of buckling behaviour of columns. This paper outlines the challenges in measurement of residual stresses using neutron diffraction in fabricated high strength steel square tubes. The residual stress line scans and maps were measured using the Kowari Strain Scanner located at the Australian Nuclear and Science Organisation (ANSTO) in Australia.

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