Development of Residual Stress Profiles for Defect Tolerance Assessments of Thick Section Electron Beam Welds

2014 ◽  
Author(s):  
P. R. Hurrell ◽  
B. M. E. Pellereau ◽  
C. M. Gill ◽  
E. Kingston ◽  
D. Smith ◽  
...  
Keyword(s):  
Residual Stress ◽  
Electron Beam ◽  
Welding Process ◽  
Stress Fields ◽  
Thick Section ◽  
Stress Distributions ◽  
Defect Tolerance ◽  
Eb Welding ◽  
Section Electron ◽  
Stress Profiles

This paper describes the results of weld model analysis and deep hole-drilling measurements undertaken to evaluate residual stress distributions in austenitic and ferritic steel thick section electron beam welds. The work was undertaken in support of a Rolls-Royce and TWI development programme in the UK, for a Reduced Pressure Electron Beam (RPEB, 0.1 to 1mbar) welding process using a mobile local vacuum seal for the manufacture of thick section pressure vessel and pipe welds for nuclear power plant applications. Measurements were undertaken on representative mock-ups including a 160mm thick SA508-3 forging circumferential seam weld, in both the as-welded and furnace post weld heat treated condition. A 316L stainless steel plate butt weld and a 304L pipe girth weld of 80mm and 36mm thickness respectively were also analysed. There is now considered to be sufficient understanding of the residual stress fields generated by thick Electron Beam (EB) welds, to propose through thickness ‘upper bound’ R6 Level 2 stress profiles for use in defect tolerance assessments. The intention is to incorporate residual stress profiles of this type into the R6 structural integrity assessment procedure, following peer review. This would represent a significant step forward in demonstrating technology readiness for plant applications. It is also anticipated that an ASME Code Case will be drafted and proposed for the RPEB welding process. EB welding is a relatively low heat input process, compared with a multi-pass arc weld, such that the fusion zone and heat affected zone are narrow. The centre of an EB weld is the last region to solidify and cool-down, so typically there is a high degree of restraint to weld metal contraction, thereby generating a highly tri-axial yield magnitude tensile stress state at the mid-thickness location. The stress components acting in the longitudinal welding direction and through-thickness orientation tend to be large in the centre of EB welds of high aspect ratio (depth / width). By contrast, lower stress levels are produced on the surfaces acting transverse to the weld plane compared to conventional multi-pass metal arc welds. The transverse stress component is most likely to be required for the assessment of any postulated EB welding defects. The residual stress field decays rapidly with distance from the EB joint into the adjacent parent metal. Symmetrical stress distributions are typically generated in a 1-pass EB plate weld and stress fields are characteristically sinusoidal of wavelength between 1 and 4 times the section thickness.

Residual Stresses in Thick-Section Electron Beam Welds in RPV Steels

2016 ◽  
Author(s):  
Anastasia N. Vasileiou ◽  
Mike C. Smith ◽  
David Gandy ◽  
Arben Ferhati ◽  
Remi Romac ◽  
...  
Keyword(s):  
Residual Stress ◽  
Electron Beam ◽  
Finite Element Modelling ◽  
Electron Beam Welding ◽  
Welding Process ◽  
Structural Performance ◽  
Thick Section ◽  
Element Modelling ◽  
Section Electron ◽  
Made In

Low pressure electron beam welding offers the prospect of large increases in productivity for thick section welds in RPV steels. However, it is important to understand how this welding process affects the structural performance of the completed weld. This paper reviews and presents key results from a programme of weldment manufacture, materials characterisation, residual stress measurements, and finite element modelling of EB welds made in plate of three thicknesses, 30mm, 130mm, and 200mm, and in three steels: SA508 Gr 2, SA508 Gr 3 C1 1, and SA516 Gr 70.

Numerical Methods to Predict Distortion in Welded Components

2008 ◽  
Author(s):  
N. A. Leggatt ◽  
R. J. Dennis ◽  
P. J. Bouchard ◽  
M. C. Smith
Keyword(s):  
Residual Stress ◽  
Numerical Methods ◽  
Structural Integrity ◽  
Large Strain ◽  
Stress Fields ◽  
Specimen Thickness ◽  
Single Bead ◽  
Stress Profiles ◽  
Welding Processes ◽  
Integrity Assessments

Numerical methods have been established to simulate welding processes. Of particular interest is the ability to predict residual stress fields. These fields are often used in support of structural integrity assessments where they have the potential, when accurately characterised, to offer significantly less conservative predictions of residual profiles compared to those found in assessment codes such as API 579, BS7910 and R6. However, accurate predictions of residual stress profiles that compare favourably with measurements do not necessarily suggest an accurate prediction of component distortions. This paper presents a series of results that compare predicted distortions for a variety of specimen mock-ups with measurements. A range of specimen thicknesses will be studied including, a 4mm thick DH-36 ferritic plate containing a single bead, a 4mm thick DH-36 ferritic plate containing fillet welds, a 25mm thick 316L austenitic plate containing a groove weld and a 35mm thick esshete 1250 austenitic disc containing a concentric ring weld. For each component, distortion measurements have been compared with the predicted distortions with a number of key features being investigated. These include the influence of ‘small’ vs ‘large’ strain deformation theory, the ability to predict distortions using simplified analysis methods such as simultaneous bead deposition and the influence of specimen thickness on the requirement for particular analysis features. The work provides an extremely useful insight into how existing numerical methods used to predict residual stress fields can be utilised to predict the distortions that occur as a result of the welding fabrication process.

FE Predictions of Temperature Distributions in a Multipass Welded Piping Branch Junction

2004 ◽  
Author(s):  
Wei Jiang ◽  
Kadda Yahiaoui ◽  
Chang J. Wang ◽  
Frank R. Hall ◽  
Tahar Laoui
Keyword(s):  
Residual Stress ◽  
Welding Process ◽  
Stress Distributions ◽  
Temperature Dependent ◽  
Material Microstructure ◽  
Temperature Distributions ◽  
Control Schemes ◽  
Complex Temperature ◽  
Walled Cylinder ◽  
Comprehensive Study

This contribution deals with the complex temperature profiles that are generated by the welding process in the intersection region of thick walled, cylinder-cylinder junctions. These affect material microstructure, mechanical properties and residual stresses. Knowledge of the thermal history and temperature distributions are thus critical in developing control schemes for acceptable residual stress distributions to improve in-service component behavior. A comprehensive study of 3D temperature distributions in a stainless steel tee branch junction during a multipass welding process is presented. A newly developed partitioning technique has been used to mesh the complex intersection areas of the welded junction. Various phenomena associated with welding, such as temperature dependent material properties, heat loss by convection and latent heat have been taken into consideration. The temperature distribution at various times after deposition of certain passes and the thermal cycles at various locations are reported. The results obtained in this study will be used for on-going and future analysis of residual stress distributions. The meshing technique and modeling method can also be applied to other curved, multipass welds in complex structures.

Investigation Into Residual Stresses in a Small Bore Pipe Weld With Stacked Stop/Start Locations

2020 ◽  
Author(s):  
Ben Pellereau ◽  
Simon Walter ◽  
Paul Pembury
Keyword(s):  
Residual Stress ◽  
Welding Process ◽  
3D Models ◽  
Defect Tolerance ◽  
Horizontal Pipe ◽  
Weld Residual Stress ◽  
High Fatigue ◽  
Fracture Assessment ◽  
Peak Location ◽  
Level 1

Abstract Small bore austenitic stainless steel pipework is used in a number of nuclear plant systems. Many of these locations are subjected to large thermal shocks and therefore have high fatigue usage factors. Their justification therefore often includes a fatigue crack growth and fracture assessment, for which a key input is the residual stress associated with the welding process, in UK assessments these are typically taken from the R6 compendium. A common process used for these welds is manual tungsten inert gas welding, due to access difficulties each pass is usually completed in two halves. The stop-start locations for each weld run are sometimes stacked, especially in horizontal pipe runs where each weld operation starts at the bottom of the pipe and progresses upwards. The stack up of stop-start locations is likely to lead to considerable circumferential variation in weld residual stress, potentially resulting in stresses that locally exceed the R6 profiles. This paper presents results from a series of FE models for a single small bore pipe weld. The simulated weld is a 3-pass manual TIG weld with an EB insert in a 2 inch (50 mm) nominal diameter pipe. Both 2D and 3D models were run. The results of the modelling are then compared with measurements of weld mock-ups of the same weld (both with and without the stop-start stack-up). The results show that, local to the assumed stop location the predicted stresses do exceed even the R6 level 1 profile (a membrane stress equal to the 1% proof stress of the material). However, the locally enhanced stresses drop off quickly away from the peak location, so for defects of a size that may be a concern for a defect tolerance assessment, the R6 Level 1 and 2 profiles remains appropriate or bounding.

Welding-Brazing Characteristic in Electron Beam Joining Vanadium Alloy and Stainless Steel

2015 ◽  
Vol 1088 ◽  
pp. 130-134
Author(s):  
Ya Rong Wang ◽  
Yang Yu ◽  
Wei Chao Zhang
Keyword(s):  
Stainless Steel ◽  
Electron Beam ◽  
Electron Beam Welding ◽  
High Vacuum ◽  
Welding Process ◽  
Dissimilar Materials ◽  
Temperature Fields ◽  
Residual Tensile Stress ◽  
Stress Distributions ◽  
Vanadium Alloy

The high vacuum electron beam welding-brazing was used to joining vanadium alloy (V-5Cr-5Ti) with stainless–steel (HR-2). The temperature fields and stress distributions in the V-5Cr-5Ti/HR-2 joint during the welding process were numerically simulated and the effect of the electron beam off-set distance was studied. The results show that the accurate heat input and proper molten pool position can help to control the fusion ratio of the V/Fe. The electron beam should off set on the stainless steel side rather than vanadium alloy side, and the best range of the distances off-set is 0-0.5mm. The residual stress appears to be bimodal and asymmetric. The maximum lateral residual tensile stress reached 388MPa at the V-5Cr-5Ti side. The joints with the characters of welding and brazing and the metallurgically bonded joint was achieved with 0.3mm beam off-set. With the liquid-to-solid interalloying of dissimilar materials controlled well, a reaction zone is gained on the interface. The maximum tensile strength of vanadium alloy/stainless-steel dissimilar alloy jointswas up to 200MPa with no defect.

Measurement and Simulation of Residual Stresses of Electron Beam Welding Joint of Pure Aluminum

2012 ◽  
Vol 184-185 ◽  
pp. 649-652
Author(s):  
Gui Fang Guo ◽  
Shi Qiong Zhou ◽  
Liang Wang ◽  
Li Hao ◽  
Ze Guo Liu
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Electron Beam ◽  
Residual Stresses ◽  
Electron Beam Welding ◽  
Pure Aluminum ◽  
Research Result ◽  
Welding Process ◽  
Hole Drilling ◽  
Longitudinal Residual Stress

The effects of electron beam welding on the residual stresses of welded joints of pure aluminum plate 99.60 are studied by through-hole-drilling and blind-hole-drilling method. Meanwhile, based on the thermal elastic-plastic theory, and making use of ANSYS finite element procedure, a three - dimensional finite element model using mobile heat source of temperature and stresses field of electron beam welding in pure aluminum is established. The welding process is simulated by means of the ANSYS software. The results show that the main residual stress is the longitudinal residual stress, the value of the longitudinal residual stress is much larger than the transverse residual stress. But the residual stress in the thickness is rather small. And in the weld center, the maximum value of residual stresses is lower than its yield strength. The simulation results about the welded residual stresses are almost identical with the experimental results by measuring. So the research result is important to science research and engineering application.

Measured and predicted residual stresses in thick section electron beam welded steels

2014 ◽  
Vol 120-121 ◽  
pp. 66-79 ◽  
Author(s):  
D.J. Smith ◽  
G. Zheng ◽  
P.R. Hurrell ◽  
C.M. Gill ◽  
B.M.E. Pellereau ◽  
...  
Keyword(s):  
Electron Beam ◽  
Residual Stresses ◽  
Thick Section ◽  
Section Electron

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.

scholarly journals Finite element modelling of multi-pass fusion welding with application to complex geometries

2007 ◽  
Vol 221 (4) ◽  
pp. 225-234 ◽  
Author(s):  
W Jiang ◽  
K Yahiaoui
Keyword(s):  
Residual Stress ◽  
Three Dimensional ◽  
Welding Process ◽  
Industrial Applications ◽  
Fusion Welding ◽  
Modelling Technique ◽  
Welding Parameters ◽  
Complex Geometries ◽  
Stress Distributions ◽  
Element Removal

The current paper presents recently completed work in the development of advanced multi-pass weld modelling procedures, with the ultimate objective of predicting weld residual stress distributions in thick-walled complex geometries. The modelling technique was first developed using simple three-dimensional geometries, for which experimental data was available for validation purposes. All the non-linearities associated with welding, including geometry, material, and boundary non-linearities, as well as heat source movement were taken into account. The element removal/reactivate technique was employed to simulate the deposition of filler material. Combined with a newly developed meshing technique, the model was then applied to predict residual stress distributions for a relatively thick stainless steel piping branch junction. Finally, a parametric study was conducted to assess the effects of various manufacture-related welding parameters on the final residual stress fields. The interpass temperature and cooling rate were found to be the two most sensitive parameters affecting resultant residual stresses. The residual stress profiles can be optimized relatively easily by adjusting these parameters. This research demonstrated that the developed modelling technique has potential in multi-pass welding process optimization and wide industrial applications including weld repairs.

Sign in / Sign up

Export Citation Format

Share Document