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.

scholarly journals Prediction of Dilution and Its Impact on the Metallurgical and Mechanical Behavior of a Multipass Steel Weldment

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Y. L. Sun ◽  
C. J. Hamelin ◽  
T. F. Flint ◽  
A. N. Vasileiou ◽  
J. A. Francis ◽  
...  
Keyword(s):  
Weld Metal ◽  
Mechanical Behavior ◽  
Arc Welding ◽  
Measurement Data ◽  
Base Material ◽  
Thermocouple Measurement ◽  
Cross Sectional ◽  
Steel Weldment ◽  
Gas Tungsten Arc ◽  
Compressive Stresses

Abstract A three-pass groove weld made by gas-tungsten arc welding in a 20-mm thick SA508 steel plate is modeled to predict the thermal, metallurgical, and mechanical behavior. The dilution for each pass is estimated as the proportion of base material in the weld metal, based on the predicted cross-sectional areas for the fusion zone (FZ) associated with each individual pass. The temperature predictions are consistent with the thermocouple measurement data and cross-weld macrographs. The predicted microstructures are qualitatively compared with the observed microstructures in cross-weld optical micrographs. The measured hardness is then used to quantitatively validate the predictions for postweld microconstituents (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 the dilution significantly affects the metallurgical and mechanical properties of weld metal (either as-deposited or reheated), and its consideration notably improves the predictions for microstructure and residual stress in the multipass steel weldment. Furthermore, the increase in dilution promotes the formation of martensite, which enhances the hardness, and leads to lower tensile stresses (or higher compressive stresses) in the weld metal. Such behavior arises due to the higher hardenability of the base material employed in this study, coupled with delayed austenite decomposition on cooling.

Microstructure, mechanical and corrosion properties of TIG welded Hastelloy C-276

2020 ◽  
Vol 62 (9) ◽  
pp. 883-887
Author(s):  
Mustafa Tümer
Keyword(s):  
Weld Metal ◽  
Potentiodynamic Polarization ◽  
Base Material ◽  
Corrosion Properties ◽  
Gas Tungsten Arc ◽  
Industrial Alloy ◽  
Weld Metal Microstructure ◽  
Mechanical And Corrosion Properties ◽  
Metal Microstructure ◽  
The Impact

Abstract Hastelloy C-276 is a corrosion resistant nickel based solid solution hardened industrial alloy which has superior mechanical and corrosion properties. In this study, Hastelloy C-276 alloy was welded via the GTAW (Gas tungsten arc welding) method using ERNiCrMo-4 filler metal. Tensile, bending and notch impact tests were performed to determine the mechanical properties. The microstructure of the weld metal was investigated by light microscopy (LM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The impact toughness values of the heat affected zone (HAZ) showed a better performance than those of the weld metal. In addition, the corrosion properties of the weld metal and the base material were investigated by potentiodynamic polarization tests. Electrochemical potentiodynamic polarization parameters were determined according to corrosion behavior and microstructure properties. In particular, the corrosion rate of the weld metal increased because of the Mo-rich phases deposited in the weld metal microstructure.

Residual Stress Modeling of Warm-Bent Tight-Radius CANDU Feeder Bends

2008 ◽  
Author(s):  
Y. Ding ◽  
M. Yetisir
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Thickness Distribution ◽  
Measurement Data ◽  
Future Research ◽  
Cross Sectional ◽  
Simulation Results ◽  
Sectional Shape ◽  
Neutron Diffraction Technique

In one CANDU® nuclear station, a few feeder piping failures have occurred because of stress corrosion cracking. All the cracks were located in tight-radius bends. Root cause analyses indicated that the residual stress played a significant role in these failures. Residual stress measurements using the neutron diffraction technique have been performed to quantify the residual stresses for a large number of feeder bends. Numerical simulations have also been performed to supplement the measurement data. This paper presents the modeling work carried out for 2.5” warm-bent tight-radius feeder bends using LS-DYNA®. The warm-bending process was divided into heating, bending, springback and cooling stages. The simulation results were compared to the measurement data using the neutron diffraction technique. Good agreement was achieved between the trends of simulation results and the measured residual stresses in feeder bends. Additionally, it was found that the predicted cross-sectional shape and wall thickness distribution agreed well with the measurements. Limitations of the simulation work were summarized and recommendations for future research were made based on this study.

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.

Measurement of Residual Stresses in Linear Friction Welded In-Service Inconel 718 Superalloy

2016 ◽  
Vol 879 ◽  
pp. 1800-1806 ◽  
Author(s):  
M. Smith ◽  
L. Bichler ◽  
D. Sediako
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Base Material ◽  
Peak Stress ◽  
Weld Interface ◽  
Aerospace Alloys ◽  
Aero Engine ◽  
Linear Friction ◽  
Inconel 718 Superalloy ◽  
Residual Strains

Measurement of residual strains by neutron diffraction of linear friction welded Inconel® 718 (IN 718) superalloy acquired from a mid-service aero-engine disk was undertaken in this study. Residual strain and stress throughout the various weld regions including the heat affected zone (HAZ), thermomechanical affected zone (TMAZ) and dynamically recrystallized zone (DRX) were characterized. The residual stresses were observed to increase from the base material to the weld interface, with a peak stress at the weld interface in all orthogonal directions. The trends for residual stress across the weld are in agreement with other work published in literature for solid state welding of aerospace alloys, where high residual stresses were commonly reported at the weld interface.

scholarly journals Residual stresses in thermite welded rails: significance of additional forging

2020 ◽  
Vol 64 (7) ◽  
pp. 1195-1212
Author(s):  
B. Lennart Josefson ◽  
R. Bisschop ◽  
M. Messaadi ◽  
J. Hantusch
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Residual Stresses ◽  
Weld Metal ◽  
Welding Process ◽  
Surface Zone ◽  
Fe Model ◽  
Uneven Surface ◽  
Residual Stress Field ◽  
High Dynamic

Abstract The aluminothermic welding (ATW) process is the most commonly used welding process for welding rails (track) in the field. The large amount of weld metal added in the ATW process may result in a wide uneven surface zone on the rail head, which may, in rare cases, lead to irregularities in wear and plastic deformation due to high dynamic wheel-rail forces as wheels pass. The present paper studies the introduction of additional forging to the ATW process, intended to reduce the width of the zone affected by the heat input, while not creating a more detrimental residual stress field. Simulations using a novel thermo-mechanical FE model of the ATW process show that addition of a forging pressure leads to a somewhat smaller width of the zone affected by heat. This is also found in a metallurgical examination, showing that this zone (weld metal and heat-affected zone) is fully pearlitic. Only marginal differences are found in the residual stress field when additional forging is applied. In both cases, large tensile residual stresses are found in the rail web at the weld. Additional forging may increase the risk of hot cracking due to an increase in plastic strains within the welded area.

Residual Stress Evaluation of Ni Based Weld Metal Using Neutron Diffraction Method

2006 ◽  
Vol 524-525 ◽  
pp. 697-702 ◽  
Author(s):  
Shinobu Okido ◽  
Hiroshi Suzuki ◽  
K. Saito
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Neutron Diffraction ◽  
Weld Metal ◽  
Diffraction Method ◽  
Fem Analysis ◽  
Butt Weld ◽  
Stress Evaluation ◽  
Neutron Diffraction Method

Residual stress generated in Type-316 austenitic stainless steel butt-weld jointed by Inconel-182 was measured using a neutron diffraction method and compared with values calculated using FEM analysis. The measured values of Type-316 austenitic stainless steel as base material agreed well with the calculated ones. The diffraction had high intensity and a sharp profile in the base metal. However, it was difficult to measure the residual stress at the weld metal due to very weak diffraction intensities. This phenomenon was caused by the texture in the weld material generated during the weld procedure. As a result, this texture induced an inaccurate evaluation of the residual stress. Procedures for residual stress evaluation to solve this textured material problem are discussed in this paper. As a method for stress evaluation, the measured strains obtained from a different diffraction plane with strong intensity were modified with the ratio of the individual elastic constant. The values of residual stress obtained using this method were almost the same as those of the standard method using Hooke’s law. Also, these residual stress values agreed roughly with those from the FEM analysis. This evaluation method is effective for measured samples with a strong texture like Ni-based weld metal.

Validation of a numerical model used to predict phase distribution and residual stress in ferritic steel weldments

2014 ◽  
Vol 75 ◽  
pp. 1-19 ◽  
Author(s):  
Cory J. Hamelin ◽  
Ondrej Muránsky ◽  
Michael C. Smith ◽  
Thomas M. Holden ◽  
Vladimir Luzin ◽  
...  
Keyword(s):  
Residual Stress ◽  
Numerical Model ◽  
Ferritic Steel ◽  
Phase Distribution

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.

Prediction for Post-Forming Spring Back of CICC in the Superconducting Tokamak Fusion Device via Virtual Manufacturing

2000 ◽  
Author(s):  
Yeong Sung Suh ◽  
Jong Sung Ahn ◽  
Sun Woong Choi ◽  
Hyun Ki Park ◽  
Yong Jin Kim ◽  
...  
Keyword(s):  
Residual Stress ◽  
Cross Section ◽  
Virtual Manufacturing ◽  
Von Mises Stress ◽  
Radius Of Curvature ◽  
Spring Back ◽  
Cross Sectional ◽  
Fusion Device ◽  
Roll Bending ◽  
Superconducting Tokamak

Abstract To construct the CICC for the superconducting Tokamak fusion device, the 3-roll bending, that inherently has a difficulty to form the coil with accurate radius of curvature, is used for continuous winding. In order to obtain precise dimension, a trial-an-error operation is inevitable. To reduce the effort of tryout, a relation between travel of the bending roller and spring back displacement was obtained via virtual manufacturing. The radius of CICC after forming was expressed as a function of the bend-roll travel. Next, the variation of the CICC cross-section (reduction of the conduit cross-section) was investigated during the first turn and during conduit bending with largest curvature. With largest curvature, the cross-sectional area was not much reduced. Finally, the residual stress on the CICC before roll bending was measured in order to examine the influence of the original residual stress on the final deformation behavior. The principal stress and von Mises stress were measured at the surface of CICC using specially designed strain gauge. The measured values were considered in the virtual forming. The results indicate that the residual stresses generated during the fabrication of the CICC (before coiling) do not have much influence on the final stress state.

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