Detailed Simulation of an Overlay Repair on a 14” Dissimilar Material Weld

2006 ◽  
Author(s):  
Stephan Courtin ◽  
Philippe Gilles
Keyword(s):  
Residual Stress ◽  
Numerical Approach ◽  
Dissimilar Material ◽  
Compressive Stresses ◽  
Weld Material ◽  
Piping Systems ◽  
Manufacturing Procedure ◽  
Detailed Simulation ◽  
Overlay Welding ◽  
Pipe Geometry

In nuclear reactors, ferritic low alloy steel heavy section components are connected with austenitic stainless steel piping systems. Despite a special manufacturing procedure to ensure a good resistance of the joint, several experiences from the field confirm sensitivity to fatigue and corrosion in this type of junction. Overlay welding is a process widely used to mitigate dissimilar material weld (DMW) stress corrosion cracking by replacing inside tensile stresses by compressive stresses. Taking into account the costs generated by mock-up manufacturing, predictive Finite Element (FE) residual stress calculations are of great interest to prove the effectiveness of the overlay welding and to adjust the parameters of the process and particularly the overlay thickness. This paper presents residual stress computations performed by Framatome-ANP on a 14” pipe geometry, resembling many mid size DMW in the US. Considering 2D axisymmetric hypotheses, the analysis simulates each elementary step of the mock-up manufacturing procedure. In particular, the pass-by-pass welding simulation reproduces the deposit of each bead by thermo-metallurgical and mechanical calculations. Thanks to residual stress measurements carried out on 2 mock-ups (with/without overlay), the numerical approach has been validated and highlights the beneficial overlay effect. However, some discrepancies raise various problems: the backing ring modelling, the machining heating effect, the experimental scatter and the weld material hardening. The simulation being able to analyze the influence of an overlay layer going up to 1 time the original pipe thickness, further work on the stabilization of the residual stress fields obtained here after the deposit of 4 or 5 layers, may lead to a better adjustment of the overlay thickness and to a cut in the operation costs too.

scholarly journals Concept for controlled adjustment of residual stress states in semi-finished products by gradation extrusion

2021 ◽  
Author(s):  
René Selbmann ◽  
Markus Baumann ◽  
Mateus Dobecki ◽  
Markus Bergmann ◽  
Verena Kräusel ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Experimental Tests ◽  
Residual Stress Distribution ◽  
Forming Process ◽  
Compressive Stresses ◽  
Energy Consuming ◽  
Stress States ◽  
Set Up ◽  
Time And Energy

AbstractThe residual stress distribution in extruded components and wires after a conventional forming process is frequently unfavourable for subsequent processes, such as bending operations. High tensile residual stresses typically occur near the surface of the wire and thus limit further processability of the material. Additional heat treatment operations or shot peening are often inserted to influence the residual stress distribution in the material after conventional manufacturing. This is time and energy consuming. The research presented in this paper contains an approach to influence the residual stress distribution by modifying the forming process for wire-like applications. The aim of this process is to lower the resulting tensile stress levels near the surface or even to generate compressive stresses. To achieve these residual compressive stresses, special forming elements are integrated in the dies. These modifications in the forming zone have a significant influence on process properties, such as degree of deformation and deformation direction, but typically have no influence on the diameter of the product geometry. In the present paper, the theoretical approach is described, as well as the model set-up, the FE-simulation and the results of the experimental tests. The characterization of the residual stress states in the specimen was carried out by X-ray diffraction using the sin2Ψ method.

Innovatives Zangenwalzwerkzeug*/An innovative pincer rolling tool

2016 ◽  
Vol 106 (07-08) ◽  
pp. 571-575
Author(s):  
B. Prof. Denkena ◽  
T. Grove ◽  
V. Prasanthan ◽  
K. Röttger ◽  
Z. Heni ◽  
...  
Keyword(s):  
Residual Stress ◽  
Turbine Blades ◽  
Aerospace Industry ◽  
Present Knowledge ◽  
Crack Initiation And Propagation ◽  
Compressive Stresses ◽  
Enhanced Resistance ◽  
Initiation And Propagation ◽  
Stress Profiles ◽  
Strength And Durability

In der Luft- und Raumfahrt werden höchste Anforderungen an die Belastbarkeit sowie Lebensdauer einzelner Komponenten gestellt. Bisherige Untersuchungen zeigen, dass insbesondere eingebrachte Druckeigenspannungen in der Werkstückrandzone aufgrund des erhöhten Widerstands gegen Rissbildung und -ausbreitung zu einer Lebensdauererhöhung von Turbinenschaufeln führen können. Mit dem Einsatz eines aerosolgelagerten Zangenwalzwerkzeug kann gezielt ein belastungsangepasstes Eigenspannungsprofil eingebracht werden.   In aerospace industry highest demands are placed on the strength and durability of individual components. The present knowledge shows that especially compressive stresses in the subsurface lead to an increased lifetime of turbine blades, due to the enhanced resistance to crack initiation and propagation. An innovative aerosol mounted pincer rolling tool has been developed for the induction of individual residual stress profiles into such components.

Nanohardness of DC Magnetron Sputtered W – C Coatings as a Function of Composition and Residual Stresses

2015 ◽  
Vol 662 ◽  
pp. 107-110 ◽  
Author(s):  
Michal Novák ◽  
František Lofaj ◽  
Petra Hviščová ◽  
Rudolf Podoba ◽  
Marián Haršáni ◽  
...  
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Magnetron Sputtering ◽  
Linear Increase ◽  
Indentation Modulus ◽  
Dc Magnetron Sputtering ◽  
Glass Substrates ◽  
Compressive Stresses ◽  
Deposition Parameters

The effects of residual stresses in thin W-C based coatings were investigated with the aim to find their influence on nanohardness and indentation modulus. Ten samples of W-C based coatings were deposited on microslide glass substrates using DC magnetron sputtering at the identical deposition parameters. Their thickness was in the range from 500 to 600 nm. The residual stresses in the coatings varied from 1.5 GPa up to 4.4 GPa. Increase of residual stress caused linear increase of HITfrom 16 to 19.5 GPa. This increase was only the result of the compressive stresses. EITof the studied coatings was not sensitive to residual stresses and corresponded to 185 GPa ± 15 GPa.

Modelling of Dilution Effects on Microstructure and Residual Stress in a Multi-Pass Weldment

2018 ◽  
Author(s):  
Yongle Sun ◽  
C. J. Hamelin ◽  
M. C. Smith ◽  
A. N. Vasileiou ◽  
T. F. Flint ◽  
...  
Keyword(s):  
Residual Stress ◽  
Weld Metal ◽  
Phase Distribution ◽  
Measurement Data ◽  
Base Material ◽  
Cross Sectional ◽  
Gas Tungsten Arc ◽  
Compressive Stresses ◽  
Thermal Solution ◽  
Dilution Effects

Three-pass gas tungsten arc welding in a 20-mm thick SA508 steel plate is modelled using a sequentially coupled thermal-metallurgical-mechanical model. The dilution for each pass is estimated as the proportion of base material in the weld metal, based on an analysis of the cross-sectional area of each fusion zone. The thermal solution of the weld model is validated using thermocouple measurement data and cross-weld macrographs. The predicted microstructure is qualitatively compared with that observed in cross-weld optical micrographs. The measured hardness distribution is used to quantitatively validate the post-weld ferritic phase distribution (e.g. the ferrite, bainite and martensite fractions), based on a hardness-microstructure correlation. The predicted residual stresses are compared with those measured by neutron diffraction. The results show that dilution significantly influences the metallurgical and mechanical properties of weld metal (either as-deposited or reheated), and its consideration notably improves microstructure and residual stress predictions for a multi-pass steel weldment. For the weldment considered, an increase in dilution promotes the formation of martensite, enhances the hardness and leads to lower tensile stresses (or higher compressive stresses) in the weld metal. Such behaviour arises due to the higher hardenability of the base material, coupled with delayed austenite decomposition on cooling.

The Mechanics Basis of Residual Stress Profiles in Proposed API 579 Appendix E

2006 ◽  
Author(s):  
P. Dong ◽  
Z. Cao
Keyword(s):  
Residual Stress ◽  
Heat Input ◽  
Stress Measurement ◽  
Measurement Data ◽  
Stress Profile ◽  
Continuous Change ◽  
Parametric Function ◽  
Residual Stress Profile ◽  
Stress Profiles ◽  
Pipe Geometry

In this paper, the mechanics basis underlying the parametric through-thickness residual stress profiles proposed for the revised API 579 Appendix E are presented. The proposed residual stress profiles are governed to a large extent by a unified parametric function form valid for a broad spectrum of pipe and vessel welds. The functional relationship is established based on the comprehensive knowledge base developed within a recent major international joint industry project (JIP) under the auspice of Pressure Vessel Research Council (PVRC) and a large amount of residuals stress measurement data from recent literature. One of the most important features associated with the proposed revision is that residual stress profile is uniquely determined by two important sets of governing parameters: (1) parameters relevant to pipe geometry, i.e., r/t and t; (2) a parameter related to welding linear heat input Q (J/mm), referred to as the characteristic heat input Qˆ which has a dimension of J/mm3. As a result, the corresponding through-wall residual stress distribution exhibits a continuous change as a function of r/t, t, and Qˆ, instead of falling into a few discrete and unrelated profiles, as seen in the current Codes and Standards.

Effects of Flange Width Ratio on the Residual Stresses in Welded Monosymmetric I-Section

2014 ◽  
Vol 501-504 ◽  
pp. 574-577
Author(s):  
Zhuang Nan Zhang ◽  
Xin Zhao ◽  
Ya Nan Zhao
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Residual Stress Distribution ◽  
Welding Residual Stress ◽  
Width Ratio ◽  
Residual Tensile Stress ◽  
Growth Trend ◽  
Finite Element Software ◽  
Compressive Stresses ◽  
Peak Value

This paper used ANSYS finite element software to simulate the residual stress of the welded monosymmetric I-section and obtain residual stress distribution curves, analyzed the influence of flange width ratio on welding residual stress peak value and the stress distribution. The studies have shown that: with the flange width ratio decrease gradually, peak value of residual stress in flange and web is to increase; peak value of residual tensile stresses in both flange and web close to the steel yield strength fy, peak value of residual compressive stresses is 0.4fy in wide flange and the web near wide flange and in narrow flange and web near narrow flange is 0.3fy; the distribution of the residual tensile stress in the flange and web have growth trend.

Laser Shock Processing of Titanium Alloy Blade and FEM Simulation

2013 ◽  
Vol 456 ◽  
pp. 125-128
Author(s):  
Bing Yan ◽  
Rui Wang
Keyword(s):  
Residual Stress ◽  
Titanium Alloy ◽  
Residual Stresses ◽  
Fem Simulation ◽  
Laser Shock ◽  
Laser Shock Processing ◽  
Tc4 Titanium Alloy ◽  
Compressive Stresses ◽  
Maximum Value ◽  
Shock Processing

The aim of this article is to analyze the residual stresses field in a TC4 titanium alloy blade by laser shock processing (LSP).LSP is a new surface processing technology, it uses the laser shock wave to act on the surface of the target and form residual compressive stresses field. The ABAQUS software is applied to simulate the LSP of TC4 titanium alloy blade, and the distributions of the residual stresses field are analysed.After single LSP,the maximum value of residual stress on the surface is 309 MPa.The residual stresses on the surface increase first and then decrease.The residual stresses at the depth continue decreasing with the increase of the depth.After multiple LSP,the maximum value of residual stress on the surface is increased and plastically affected depth is increased.

Mechanical Properties and Residual Stresses in Oxide/Metal Multilayer Films Synthesized by Ion Beam Assisted Deposition

1993 ◽  
Vol 308 ◽  
Author(s):  
C. E. Kalnas ◽  
L. J. Parfitt ◽  
M. G. Goldiner ◽  
G. S. Was ◽  
J. W. Jones
Keyword(s):  
Residual Stress ◽  
Critical Strain ◽  
Ion Beam ◽  
Crack Density ◽  
Multilayer Films ◽  
Compressive Stresses ◽  
Ion Beam Assisted Deposition ◽  
Small Grains ◽  
Ductile Substrates ◽  
Metal Layers

ABSTRACTFilms of Al, Al2O3 and Al/Al2O3 microlaminates were formed by ion beam assisted deposition (IBAD) at R ratios from 0.0025 to 0.5 and film thicknesses between 150 and 2600 nm. Oxide films were amorphous while metal layers were crystalline with small grains and texture for both PVD and IBAD conditions. The average stress in the oxide film is tensile at R=0 and becomes compressive, saturating at approximately 15 eV/atom. The residual stress in the Al films is tensile over all R ratios and the stress in the microlaminate roughly follows a rule of mixtures. Deformation of ductile substrates on which films had been deposited revealed that the critical strain to fracture was strongly dependent on residual stress. Large compressive stresses in monolithic films produced by ion beam assisted deposition delayed the onset of crack initiation while the presence of multiple layers, in general, lowered the crack density at saturation, suggesting a possible ductilizing effect.

Residual Stress Measurements in a 316L Uniaxial Samples Manufactured by Laser Powder Bed Fusion

2020 ◽  
Author(s):  
C. M. Davies ◽  
P. Sandmann ◽  
T. Ronneberg ◽  
P. A. Hooper ◽  
Saurabh Kabra
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Cross Section ◽  
316L Stainless Steel ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Stress Measurements ◽  
Compressive Stresses ◽  
Central Cross Section

Abstract Uniaxial samples have been manufactured for tension/compression testing from 316L stainless steel by laser powder bed fusion (LPBF). Samples manufactured by LPBF are known to contain high levels of residual stresses. These uniaxial samples were built from a solid cylindrical rod and subsequently machined to reduce the central cross section of the sample to the required gauge diameter and improve the surface finish. Finite element (FE) models have been developed to simulate the LPBF process of the rods, their removal from the build plate and subsequent machining into the tension/compression samples. High tensile residual stresses were predicted at the surface of the samples, balances by similar magnitude compressive stresses along their axis. Post machining however, these stresses were reduced by around 80% or more. Residual stress measurements were performed on the samples post machining using the neutron diffraction techniques. These measurements confirmed that negligible residual stresses remained in the samples post removal from the build plate and machining.

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