Residual Stress Measurements Using the Contour, Deep-Hole Drilling and Neutron Diffraction Methods in T-Section Specimens

2016 ◽  
Author(s):  
Karim Serasli ◽  
Douglas Cave ◽  
Ed Kingston
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Complex Geometry ◽  
Contour Method ◽  
Hole Drilling ◽  
Deep Hole ◽  
Premature Failure ◽  
Deep Hole Drilling ◽  
The Wire

The presence of high magnitude residual stresses in welded components causes material degradation, local yielding and plastic deformation. Their presence provides the potential for premature failure and compromises the integrity of a structure. This paper presents a review of work carried out to ascertain the residual stresses present within T-section specimens, made from ferritic steel, in their as-welded condition. The standard and incremental deep hole drilling (DHD and iDHD) techniques, the neutron diffraction (ND) and the contour method were applied to characterise the residual stresses in the regions in and around the two fillet welds of the specimens and the surrounding parent material within which the balancing residual stresses needed to be measured. The results of these measurements are presented and compared to highlight agreements and discrepancies in the measured residual stress distributions using these different techniques. A compendium of measurements at a similar location in various T-sections and their comparison with the BS7910 standard show that the measured longitudinal distributions are similar despite the observed scatter. Finally, this paper briefly attempts to investigate and discuss the technical challenges identified when applying the contour method to complex geometry components. The constraint of the specimen during the wire electro-discharge machining (EDM) process, the quality of the wire EDM cut made and the analysis of the raw data for the conversion into residual stresses directly affect the accuracy of the contour method results. The identification and investigation of these challenges lead to continuous improvements of the contour method procedure and reduce uncertainties of the measurement.

Simulation and Measurement of Residual Stresses in a Stainless Steel Ring Welded Circular Disc

2012 ◽  
Author(s):  
Gang Zheng ◽  
Sayeed Hossain ◽  
Mike Smith ◽  
David Smith
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Stress Measurement ◽  
Circular Disc ◽  
Hole Drilling ◽  
Deep Hole ◽  
Deep Hole Drilling ◽  
Hole Drilling Method ◽  
Drilling Method

Residual stresses were predicted and measured in a circular disc containing a partial ring weld. This study first created an axisymmetric finite element model so that the process of introducing the ring weld was simulated using thermal and mechanical modelling. The resulting residual stresses were then mapped onto a 3D model which included the necessary mesh and boundary conditions to simulate the process of residual stress measurement using the deep hole drilling method. Then an experimental programme of residual stress measurement using the deep hole drilling method and the neutron diffraction technique was conducted on the welded circular disc. The results from the deep hole drilling measurements matched well with the neutron diffraction results on the original stress field in the ring weld. While comparison between measurements and predicted residual stresses show that predicted hoop stresses are slightly higher than measured, there is in general a fair comparison between measured and predicted residual stress.

Analysis and Optimization of the Deep-Hole Drilling Technique in Measuring Complex Residual Stress

2017 ◽  
Author(s):  
Gang Zheng ◽  
Sayeed Hossain ◽  
Feng Shen ◽  
Chris Truman
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Longitudinal Axis ◽  
Hole Drilling ◽  
Internal Diameter ◽  
Deep Hole ◽  
Element Analysis ◽  
Deep Hole Drilling ◽  
Drilling Technique ◽  
Technique Comparison

The aim of the present study was to utilize a complex residual stress generated within a welded circular disc to further investigate the standard deep-hole drilling (DHD) technique and the newly developed over-coring deep-hole drilling (oDHD) technique in accurately measuring residual stresses well over yield stress. Finite Element Analysis (FEA) was used to optimize and extend the deep-hole drilling technique and improve its accuracy. The standard DHD procedure involves 4 steps. (1) A reference hole is gun-drilled through the component. (2) The internal diameter of the reference hole is measured at different angular positions through the depth of the component. (3) A cylindrical section with the reference hole as its longitudinal axis is trepanned free from the component. (4) Finally, the relaxed internal diameter is re-measured at the same angular positions and the same depths. The drilling, trepanning procedures and the parameters of the deep-hole drilling technique were all studied in detail to optimize the technique. Comparison is made between the FEA predicted residual stress in the weld, the measurements and the reconstructed residual stresses of the measurements. The close correlations confirmed the suitability of new modifications made in the deep-hole drilling technique to account for plasticity when measuring near yield residual stresses present in a component.

Measurement of residual stresses in T-plate weldments

2003 ◽  
Vol 38 (4) ◽  
pp. 349-365 ◽  
Author(s):  
R. C Wimpory ◽  
P. S May ◽  
N. P O'Dowd ◽  
G. A Webster ◽  
D J Smith ◽  
...  
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Plastic Zone ◽  
Residual Stresses ◽  
Plate Thickness ◽  
Welding Process ◽  
Plastic Zone Size ◽  
Hole Drilling ◽  
Stress Distributions ◽  
Premature Failure

Tensile welding residual stresses can, in combination with operating stresses, lead to premature failure of components by fatigue and/or fracture. It is therefore important that welding residual stresses are accounted for in design and assessment of engineering components and structures. In this work residual stress distributions, obtained from measurements on a number of ferritic steel T-plate weldments using the neutron diffraction technique and the deep-hole drilling method, are presented. It has been found that the residual stress distributions for three different plate sizes are of similar shape when distances are normalized by plate thickness. It has also been found that the conservatisms in residual stress profiles recommended in current fracture mechanics-based safety assessment procedures can be significant—of yield strength magnitude in certain cases. Based on the data presented here a new, less-conservative transverse residual stress upper bound distribution is proposed for the T-plate weldment geometry. The extent of the plastic zone developed during the welding process has also been estimated by use of Vickers hardness and neutron diffraction measurements. It has been found that the measured plastic zone sizes are considerably smaller than those predicted by existing methods. The implications of the use of the plastic zone size as an indicator of the residual stress distributions are discussed.

Uncertainty in Residual Stress Measurements

2008 ◽  
Author(s):  
D. M. Goudar ◽  
S. Hossain ◽  
C. E. Truman ◽  
D. J. Smith
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Measurement Techniques ◽  
Diffraction Method ◽  
Hole Drilling ◽  
Invasive Technique ◽  
Deep Hole ◽  
Deep Hole Drilling ◽  
Integrity Assessment ◽  
Path Lengths

Accurate characterization of residual stress in engineering components is important in structural integrity assessment. Two commonly used methods of measuring residual stress include the neutron diffraction technique and the deep-hole drilling (DHD) technique. The former is a well-known nondestructive measurement method and the latter is a semi-invasive technique which is readily available and portable. Both these measurement techniques depend on a number of physical quantities and are therefore sensitive to errors associated with the measured data. The resulting stress uncertainties can easily become significant and compromise the usefulness of the results or lead to misinterpretation of the behaviour of stress distribution. This paper describes briefly the error analysis for both techniques. Results from earlier neutron diffraction and deep hole drilling measurements are used to illustrate the errors. It is found that the average error for both techniques is about ±20MPa. In the case of the neutron diffraction method this error is acceptable for path lengths less than a few centimetres. At greater path lengths the errors become unacceptably large. In contrast the error in the DHD is independent of depth.

Residual Stress Investigation in a Stainless Steel Ring Welded Circular Disc by Over-Coring Deep Hole Drilling Simulation and Measurement

2014 ◽  
Author(s):  
Gang Zheng ◽  
Sayeed Hossain ◽  
Mike C. Smith ◽  
David J. Smith
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Stress Measurement ◽  
Circular Disc ◽  
Residual Stress Measurement ◽  
Hole Drilling ◽  
Deep Hole ◽  
Deep Hole Drilling ◽  
Welding Simulation ◽  
Drilling Simulation

A circular disc containing a partial ring weld has been devised to permit high levels of residual stress to be created in a relatively small specimen. The purpose of this research is to investigate the residual stress within the weld whilst developing a residual stress measurement method called the over-coring deep hole drilling (oDHD) method. The welding simulation, incremental deep hole drilling (iDHD) simulation and measurement and neutron diffraction were previously studied and reported in [1]. In this paper, the welding simulation results were mapped into a 3D model that included the necessary mesh and boundary conditions to simulate the process of residual measurement using the oDHD method. An experimental programme of residual stress measurement using the oDHD method was then conducted on a welded circular disc. The results from the oDHD simulation and measurement matched well with previous iDHD simulations on the original stress field in the ring weld, which also matched earlier neutron diffraction results.

Simulation and Measurement of Through–Wall Residual Stresses in a Structural Weld Overlaid Pressurizer Nozzle

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
Stephen Marlette ◽  
Paula Freyer ◽  
Michael Smith ◽  
Andrew Goodfellow ◽  
Xavier Pitoiset ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Residual Stresses ◽  
Hole Drilling ◽  
Steel Weld ◽  
Deep Hole ◽  
Deep Hole Drilling ◽  
Dissimilar Metal ◽  
Stainless Steel Weld ◽  
Stress Profiles

Full structural weld overlays (FSWOLs) have been used extensively as a repair/mitigation technique for primary water stress corrosion cracking in pressurizer nozzle dissimilar metal (DM) welds. To support an approved FSWOL design and safety submission for British Energy pressurized water reactor (PWR) nozzles, an in-depth evaluation was performed to assess the effects of a FSWOL on the through wall residual stress distribution in safety/relief pressurizer nozzles. Two safety/relief pressurizer nozzle mockups were fabricated based on British Energy’s PWR nozzle design. One mockup included the nozzle to safe-end DM weld and the safe-end to stainless steel weld, while the second mockup included the DM weld, the stainless steel weld, and a Westinghouse designed structural weld overlay. The mockups were fabricated utilizing materials and techniques that represented the plant specific nozzles as closely as possible and detailed welding parameters were recorded during fabrication. All welds were subsequently nondestructively evaluated (NDE). A thorough review of the detailed fabrication records and the NDE results was performed and several circumferential positions were selected on each mockup for subsequent residual stress measurement. The through wall residual stress profiles were experimentally measured through the DM weld centerline at the selected circumferential positions using both the deep-hole drilling (DHD) and incremental deep-hole drilling (iDHD) measurement techniques. In addition to experimental residual stress measurements, the through-wall residual stress profiles were simulated using a 2D axisymmetric ansys™ finite element (FE) model. The model utilized the application of temperature constraints on the weld elements to simulate the thermal welding cycle which greatly simplified the simulation as compared with detailed heat source modeling methods. Kinematic strain hardening was used for material modeling of the weld and base metals. A range of residual weld stress profiles was calculated by varying the time at which the temperature constraints were applied to the model. The simulation results were compared with the measurement results. It was found that the effects of the FSWOL were principally threefold. Specifically, the FSWOL causes a much deeper compressive stress field, i.e., the overlay shifts tension out toward the outside diameter (OD) surface. Furthermore, the FSWOL reduces tension in the underlying dissimilar metal weld, and finally, the FSWOL causes higher peak compressive and tensile residual stresses, both of which move deeper into the nozzle wall after the overlay is applied. Relatively good agreement was observed between the FE results and the measurements results.

Calibration of the Ultrasonic Technique Using the Deep Hole Drilling, Neutron Diffraction and Contour Residual Stress Measurement on a Ring Stiffened Cylindrical Structures

2016 ◽  
Author(s):  
Xavier Ficquet ◽  
Remi Romac ◽  
Douglas Cave ◽  
Ed J. Kingston
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Tensile Test ◽  
Stress Measurement ◽  
Measurement Techniques ◽  
Residual Stress Measurement ◽  
Hole Drilling ◽  
Deep Hole ◽  
Deep Hole Drilling ◽  
Cylindrical Structures

This paper presents the residual stress measurements carried out on a t-section representative of a ring stiffened cylindrical structures. This paper presents the work carried out to ascertain the residual stresses present within a T-plate section representative of a ring stiffened cylindrical structures. The contour, the deep hole drilling (DHD) and the neutron diffraction (ND) methods were applied to determine the longitudinal component of residual stress in the weld toe of the fillet weld in the as-welded condition. The results of these measurements are presented and compared to highlight agreements and discrepancies in the measured residual stress distributions using these different techniques. Finally, non-destructive residual stress measurement using the ultrasonic (US) technique was carried out on the component. The ultrasonic measurement provides a relative measurement and usually requires a tensile test in order to determine the acoustoelastic constant and the time of flight in a stress-free state. The tensile test requires some material to be extracted from the component. The tensile test can be avoided if other residual stress measurement techniques are used for the calibration. After the calibration the US technique can be deployed on a full-scale ring stiffened cylindrical structures to detect abnormal variation in the residual stress field.

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