Weld Research Papers - Academia.edu (original) (raw)

Predictability enables proactive control of the production instead of reactive inspection. The research presented in this thesis provides insights and tools to enable predictability in weld production. The research shows that sufficient use of process information facilitates predictability and can support the reduction of unnecessary and costly safety margins in production. This will, in the short term, affect the productivity of the company. Even more influential is the effect predictability can have on product and process development in the long term, enabling welding companies to reduce weight of their fatigue loaded structures. The result can be lower fuel consumption and increased payloads, which will increase the companies’ competitiveness. Knowledge of the process is the key to evolve towards predictable weld production. To understand variation and how the evaluation process should be designed is therefore important. A model describing evaluation process development is presen...

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- Engineering, Computer Science, Quality, Production
- by Nilesh Kumar
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- Engineering, Materials Engineering, Mechanical Engineering, Materials Science

The present study aims to simulate single-pass welds using three computer-assisted numerical approaches: an analytical-numerical algorithm for heat transfer in welds, the SmartWeld software and a finite element model implemented in the ANSYS software. Its applicability was evaluated in the prediction of the temperature distribution below the weld bead in plates of semi-infinite extension and finite thickness. The results of the simulations were compared with temperature data obtained from the welding of AISI P20 steel using the autogenous TIG process with constant direct current and energy of 10 kJ / cm. The thermo-physical properties of the base material and boundary conditions were kept similar between simulations for comparative purposes. The study shows how the simulations carried out complement each other and can be validated for their applicability in the development of welding procedures.

- by Pierre Maréchal
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- Impression
- by Jorge Pacheco
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- Materials Science, Metallurgy, Welding, Thermal

En este trabajo se desarrollo un modelo teorico-experimental para determinar el historial termico en la zona afectada termicamente (ZAT) de soldaduras al arco. El modelo fue basado en la solucion de la ecuacion de Rosenthal, modificada para placas seminfinitas. Se valido experimentalmente el modelo usando juntas disimiles de aceros AISI 316L y AISI 430 obtenidas con proceso de soldadura al arco con electrodo revestido (SMAW) y un metal de aporte E-309. Por medio de un sistema de adquisicion de datos en tiempo real y termopares ubicados estrategicamente en la ZAT se realizo la medicion de ciclos termicos durante el proceso de soldadura. Los resultados obtenidos por el modelo mostraron una excelente correlacion con respecto a los datos obtenidos experimentalmente mostrando diferencias menores al 10%, lo cual indica que el modelo podria ser un metodo potencial para reducir experimentos dirigidos a conocer la distribucion termica de soldadura al arco a partir de datos de propiedades fis...

- by Jorge Pacheco
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- Physics
- by jefferson barrera
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- Physics, Humanities

- by Miguel Sánchez Olmos
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- Physics

Tema završnog rada je zavarljivost materijala, odnosno kvaliteta zavarenih spojeva i verifikacija istih. U početnom djelu opisuje se zavarljivost čelika (nelegiranih, niskolegiranih, visokolegiranih i raznovrsnih čelika). Također, spominje se i zavarljivost obojenih metala (aluminij i bakar). U sljedećem poglavlju razrađena je problematika verifikacije postupaka zavarivanja i verifikacija zavarivača. Četvrto poglavlje obrađuje tematiku pogrešaka u zavarenim spojevima. Nastanak hladnih pukotina i metode ispitivanja hladnih pukotina (Implant, Tekken i CTS metoda) te nastanak toplih pukotina i metode ispitivanja toplih pukotina (Varestraint i Det Norske Veritas metoda). Zadnje poglavlje bazirano je metodama ispitivanja kvalitete zavarenih spojeva. Spomenuta je ultrazvučna, penetrantska i magnetska metoda ispitivanja zavara.The topic of the final work is Introduction to welding technology design, weldability and testing of welded joints. The first chapter describes the weldability of st...

- by valentino david
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- Quality, Testing, Steel, Welding

Fracture properties of different microstructural regions of the heat affected zone (HAZ) of modified 9Cr-1Mo steel (tempered base metal, intercritical, fine grained, coarse grained with and without δ-ferrite) have been studied by Charpy impact test. Simulation technique is used to reproduce HAZ microstructures. The fine-grained region shows highest toughness and the coarse grained with δ-ferrite shows the lowest. The results have been analysed in terms of tensile properties and microstructural features. The inter particle distance seems to affect the energy absorbed up to fracture both in the tensile tests and Charpy impact test. The highest toughness is obtained for an optimum inter-particle spacing.

- by P. R. Sreenivasan
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- Microstructure, Weld, Toughness, Haz
- by HERNAN GABRIEL SVOBODA
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- Physics, Materials Science, Humanities, Metallurgy
- by cevdet meriç
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- Engineering, Materials Science, Microstructure, Metallurgy
- by Vladimir Luzin
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- Mechanical Engineering, Materials Science, Neutron Diffraction, Welding

Arc welding generally introduces undesired local residual stress states on engineering components hindering high-quality performance in service. Common procedures to reduce the tensile residual stresses are post-heat treatments or mechanical surface treatments like hammering or shot-peening. Assessments of residual stress profiles of post-weld treatments underneath the weld surface are essential, especially in high safety exigency systems like pressure vessels or piping at power plants. In this study, neutron diffraction is used to determine the stress profile after finish milling of an austenitic steel weld in order to verify a chained finite element simulation predicting the final residual stress fields including milling and welding contributions. Non-destructive measurements with spatial resolutions of less than 0.2 mm within the first 1 mm from the surface were mandatory to confirm the finite element simulations of the coarse-grained austenitic material. In the data analysis pro...

- by F. Valiorgue
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- Engineering, Materials Science, Mathematical Sciences, Welding
- by Vincent Maurel
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- Materials Science, TI, Fissuration
- by Javier Omella
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- Materials Science, Finite element method, Thermography
- by Herschel Smartt
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- Sensor, Sound, Ultrasonic, Assembly
- by Peter Hammersberg
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- Engineering, Quality, Evaluation, Test
- by Peter Hammersberg
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- Engineering, Computer Science, Six Sigma, Production economics
- by Peter Hammersberg
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- Engineering, Production economics, Welding, Hierarchy
- by Peter Hammersberg
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- Engineering, Computer Science, Evaluation methods, Implementation
- by Wim De Waele
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- Materials Science, Structural Engineering, Finite element method, Heterogeneity

Wide plate tension tests are commonly executed to investigate the integrity of defective weldsunder a uniaxial load. The specimen can be flat or curved, depending on the geometry from which it hasbeen extracted (plate or pipe). Despite its usefulness, the design of the (curved) wide plate test is still notstandardized up-to-date. This paper compares two specimen designs with a different length-to-width ratiothrough finite element analysis, using a design-of-experiments approach to account for different influentialfactors. The results reveal significant differences between the interpretation of tests with net sectioncollapse and gross section collapse, promoted by weld strength overmatch. Further, both investigateddesigns tend to provide similar estimates of failure mode, strain capacity and crack driving force. Hence,the shorter specimen is considered an acceptable alternative to the slightly more representative longerspecimen.

- by Wim De Waele
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- Engineering, Structural Engineering, Finite element method, Structural Integrity

Fatigue is a common failure mechanism of welds in offshore structures. Their lifetime prediction is hampered by a large number of influence factors related to weld (e.g., residual stresses) and environment (e.g., variable amplitude loading, hydrogen embrittlement). These challenges (among others) are tackled in the Flemish research programme MaDurOS. This paper describes an extended finite element method (XFEM) based framework, developed within the scope of this programme. It allows to include weld and environment related aspects into the numerical lifetime prediction of welded structures. This paper focuses on the three-dimensional nature of crack propagation predictions. A numerical optimization and benchmark validation are discussed to illustrate the possibilities of the framework. In future work, the developed software will be coupled with residual stress in the welds and hydrogen embrittlement and be validated with experimental input/output, allowing to evaluate the ability of ...

- by Wim De Waele
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- Engineering, Structural Engineering, Finite element method, Welding
- by Abdullah Erdemir
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- Materials Science, Structural Engineering, Finite element method, Welding

The post weld heat treatment (PWHT) was used to reduce the level of the residual stresses and increase of the crack resistance of the materal in the cnnection part. The article presents the results of the residual stress measurements... more

- by Milorad Zrilić
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- Materials Science, Metallurgy, Heat Treatment, Stress relaxation
- by Cevdet Meriç
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- Engineering, Materials Science, Microstructure, Metallurgy
- by Tomás Hernaldo Fernández Columbié
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- Materials Science, Welding, Alloy, Aluminium
- by Tomás Hernaldo Fernández Columbié
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- Materials Science, Metallurgy, Welding, minería y geología

The background of Vermeer’s Girl with a Pearl Earring (c. 1665, Mauritshuis) has, until recently, been interpreted as a flat dark space. The painting was examined in 2018 as part of the research project The Girl in the Spotlight using a combination of micro- and macro-scale analytical techniques. The stratigraphy of the background was determined from samples mounted as cross-sections, and its material composition was analysed using electron microscopy and chromatographic techniques. The underlayer contains mainly charcoal black, and the glaze contains two organic colourants—indigo and weld—and a copper drier. Deterioration of the glaze has made features in the background difficult to discern with the naked eye. Complementary imaging techniques were able to visualise Vermeer’s signature, and the suggestion of folded fabric (possibly a curtain) on the right side of the painting. The distribution of the layer(s) in the background were imaged using: infrared reflectography (900–1100 nm)...

- by Art Néss Proaño Gaibor
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- Art, Optical coherence tomography, Pearl, Indigo
- by Fermin Garciandía
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- Materials Science, Metallurgy, Welding
- by Ole Myhr
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- Materials Engineering, Mechanical Engineering, Materials Science, Humanities
- by Ole Myhr
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- Materials Engineering, Mechanical Engineering, Materials Science, Humanities
- by Christoph Markmann
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- Physics, Knowledge, Laser Welding, Geometry
- by Yaqiao Wu
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- Materials Engineering, Mechanical Engineering, Materials Science, Metallurgy
- by Yaqiao Wu
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- Materials Engineering, Mechanical Engineering, Materials Science, Metallurgy
- by Philippe A GILLES
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- Materials Science, Structural Engineering, Microstructure, Heterogeneity

In this study, the effect of oxygen in the shielding gas on the material flow behavior of the weld pool surface was discussed to clarify the dominant driving weld pool force in keyhole plasma arc welding (KPAW). To address this issue, the convection flow on the top surface of weld pool was observed using a high-speed video camera. The temperature distribution on the surface along keyhole wall was measured using the two-color pyrometry method to confirm the Marangoni force activity on the weld pool. The results show that the inclination angle of the keyhole wall (keyhole shape) increased especially near the top surface due to the decrease in the surface tension of weld pool through surface oxidation when a shielding gas of Ar + 0.5% O2 was used. Due to the change in the keyhole shape, the upward and backward shear force compositions created a large inclination angle at the top surface of the keyhole. From the temperature measurement results, the Marangoni force was found to alter the...

- by tuan nguyen van
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- Materials Science, Mechanics, Welding, Applied Sciences

RESUMEN En este estudio, los efectos de los tratamientos térmicos en el pico de envejecimiento (T6), sobre-envejecimiento (T73) y proceso de regresión y re-envejecimiento (RRA, regresión a 200 °C durante 10 min) sobre la microestructura, resistencia mecánica, corrosión por exfoliación y corrosión intergranular de aleación de aluminio 7075 ha sido investigado mediante microscopia óptica, microscopía electrónica de barrido, ensayos de tracción, ensayos ASTM G110, ensayos ASTM G34, curva de polarización y espectroscopia de impedancia electroquímica (EIS). Los resultados de los ensayos de corrosión intergranular (ASTM G110) y los ensayos de corrosión por exfoliación (ASTM G34), aplicados a los tres tratamientos definen un orden de susceptibilidad a la corrosión dada por: T6 > T73 > RRA. Las tendencias de la resistencia a la corrosión son confirmadas mediante curvas de polarización y ensayos EIS. El tratamiento térmico RRA mejora la resistencia a la corrosión intergranular-exfoliac...

- by Damian Morales Gutierrez
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- Materials Science, Matéria

In the present paper, the results of a research focused on microstructure investigation of steel welded joints by means of non destructive thermographic technique are presented. In particular, two rough joints obtained by means of irregular manual welding are analyzed. Active lock in thermography phase analysis is applied, basing on the evidence that thermal diffusivity is related to the thermal diffusion length, using the phase contrast trend as a function of the distance from the laser spot. Diffusivity is expected to be dependent on the local microstructure and vary through different directions. By the variation in diffusivity, it is possible to investigate the level of anisotropy.The results are compared with micrographic analysis. The proposed method provides an active lock-in infrared thermography analysis by means of a thermal camera and an exciting laser head to evaluate thermal diffusivity.

- by Luca Santoro
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- Engineering, Mathematical Sciences, Advanced manufacturing technology

The aim of this work is to make a contribution to study the ductile failure of polymers materials (Polyvinyldifluoride, PVDF) using the concepts of the local approach in fracture mechanics. The numerical simulation with the Ansys finite element code was carried out using a micromechanical model based on the local approach in order to study the ductile failure of polymers: the Gurson-Tvergaard-Needleman model; GTN. The validation of this finite element model was carried out using the experimental results. The GTN model faithfully reproduces the macroscopic mechanical behavior of the PVDF material in terms of stress versus strain at different level of temperature. The sensitivity of the PVDF mechanical behavior to some parameter such as: effect of triaxiality of stresses, temperature and hydrostatic pressure were examined. Secondly, the application of the elastoplastic fracture mechanics based on the determination of the J integral is used in order to study the fracture behavior of PV...

- by khelil foudil
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- Materials Science, Polymer, Composite Material
- by Jacques Besson
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- Computer Science

The objective of this investigation is to determine the relation between the transformations of phases occurring during the rotational friction welding of AA 5754 12-mm-diameter aluminum alloys. The process was carried out using a 16 K 20 lathe based on joint parameters ranging between 1 200 and 1 400 rev/min with a pressure of 0,9 and 1,9 MPa, respectively. It was determined that the friction temperature decreases as the number of revolutions increases as well as the metallurgical variation both in the thermo-mechanically affected area and in the thermally affected area. The hardness profiles show the increase by the plastic flow effect, metallurgical variations and the existence of precipitates.

- by Tomás Hernaldo Fernández Columbié
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- Materials Science, Welding, Alloy, Aluminium
- by Cevdet Meriç
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- Engineering, Materials Science, Microstructure, Metallurgy