A Method to Characterize the Fracture Resistance of Dissimilar Metal Welds

2012 ◽  
Author(s):  
A. Blouin ◽  
S. Chapuliot ◽  
S. Marie
Keyword(s):  
Fracture Resistance ◽  
Tensile Tests ◽  
Compact Specimen ◽  
Fast Method ◽  
Dissimilar Metal ◽  
Weld Joints ◽  
Laser Sensors ◽  
Edge Notch ◽  
Fracture Tests ◽  
Material Mismatch

Characterization of the fracture resistance of weld joints, and in particular dissimilar metal welds (DMW), is a huge and difficult work where no standard currently exists. As a consequence, characterizations of materials have to be done prior to the fracture tests in order to consider the mechanical aspects of the material mismatch via F.E. analysis in the fracture toughness determination. However, performing these characterization tests may imply using a lot of material, which is sometimes not available, and can be expensive. Most studies are usually realized on reduced sized mock-ups. The considered experimental mock-ups are pipes composed of a ferritic pipe welded to an austenitic one. The weld joints are made of Ni base alloys. A few small tensile samples have been extracted so that each material, even the heat affected zone (HAZ), can be characterized at low temperature. A fast method using laser sensors and a specific specimen shape has been developed and is used to identify these materials strain-stress curves at −125°C. Afterwards, these data have been used to simulate multi-material compact specimen tensile tests and single edge notch tension specimen, representing a conventional defect in the HAZ. Also, these two kinds of specimen have been extracted and the tests performed in order to compare the experimental results to the F.E. analysis. This paper presents the experimental work, the related specific devices, the F.E. analyses and the experimental analysis.

scholarly journals Efecto del mantequillado en las propiedades mecánicas de uniones soldadas disímiles en barras de refuerzo para estructuras de concreto.

2016 ◽  
Vol 6 (3) ◽  
pp. 248-261
Author(s):  
J. C. I. Ramírez-Soto ◽  
J. M. Salgado-López ◽  
J. T. Pérez-Quiroz ◽  
T. Pérez-López ◽  
J. Terán-Guillén ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Microstructural Analysis ◽  
Concrete Structures ◽  
Tensile Tests ◽  
Plain Carbon Steel ◽  
Dissimilar Metal ◽  
Weld Joints ◽  
Steel Bars ◽  
Dissimilar Metal Weld ◽  
Metal Weld

Efecto del mantequillado en las propiedades mecánicas de uniones soldadas disímiles en barras de refuerzo para estructuras de concreto RESUMENEn este trabajo se ha investigado la influencia de utilizar Inconel 182 como material de “mantequillado” en las propiedades mecánicas de uniones disimiles acero al carbono-inoxidable manufacturadas por soldadura con electrodo recubierto. Para ello se han empleado las siguientes técnicas: análisis microestructural, ensayos de microdureza Vickers y ensayos mecánicos de tensión. Se ha empleado el proceso de soldadura con electrodo recubierto por que es el más común en la soldadura de campo para la construcción. Los resultados demuestran que aun cuando las uniones disimiles sin “mantequillado” presentan defectos, sus propiedades mecánicas son superiores a las de las uniones soldadas con “mantequillado”. Esta metodología es propuesta para la rehabilitación de estructuras de concreto para ambiente marino con barras de acero como refuerzos.Palabras clave: mantequillado; uniones soldadas con materiales disimiles; propiedades mecánicas; microestructura; defectos. Effect of buttering in mechanical properties of dissimilar metal weld joints for reinforcement bars in concrete structures ABSTRACTIn this work, the influence of Inconel 182 as buttering material in the mechanical properties of dissimilar metal welds between plain carbon steel and stainless steel bars welded using SMAW has been investigated using microstructural analysis, Vickers microhardness testing, and tensile tests. Welding with SMAW process is commonly applied in field welding of concrete structures; therefore this process was selected for this work. The results indicated that even if the joints contain defects generated by the welder, the mechanical properties of dissimilar welded joint without buttering are higher than the properties of joints with buttering. This methodology is proposed for the rehabilitation of concrete structures with steel bars as reinforcements, which are located in marine enviroments.  Keywords: buttering, dissimilar metal weld joints; mechanical properties; microstructure; defects. Efeito da introdução de um terceiro material sobre as propriedades mecânicas das juntas soldadas entre aço carbono e aço inox, em barras de aço para estruturas de concreto RESUMOEste artigo investiga a influência da utilização de Inconel 182 como um terceiro material, nas propriedades mecânicas de diferentes aços inoxidáveis soldados a aços carbono com uso de eletrodo revestido. Para tanto foram usados os seguintes métodos: análise microestrutural, ensaios de microdureza Vickers e ensaios mecânicos de tensão. Tem sido empregado o processo de solda com eletrodo revestido, porque é o mais comum no campo de solda para a construção. Os resultados mostram que quando as uniões são realizadas sem esse terceiro material, as propriedades mecânicas são superiores às das juntas soldadas com auxílio do Inconel 182. Esta metodologia, ora criticada, tem sido proposta para a reabilitação de estruturas de concreto em ambiente marinho, com uso de barras de aço inox como reforços.Palavras-chave: juntas soldadas com materiais diferentes; propriedades mecânicas; microestrutura; defeitos.

The Spherical Indentation Approach for Fracture Toughness Evaluation: A Study Based on the Energy Release Rate

2018 ◽  
Author(s):  
Tairui Zhang ◽  
Weiqiang Wang ◽  
Aiju Li
Keyword(s):  
Fracture Toughness ◽  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Damage Mechanism ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Spherical Indentation ◽  
Material Damage ◽  
Fracture Tests

In this study, we investigated the drawbacks of previous studies regarding the evaluation of fracture toughness from spherical indentation tests (SITs). This was achieved by an examination of the material damage mechanism during indentation tests, uniaxial tensile tests, and Mode I/II fracture tests. A new approach based on the energy release rate was proposed in this study to evaluate the fracture toughness of ductile metals. Scanning electron microscope (SEM) observations revealed that the mechanism for material damage during an indentation test was different with the material damage in uniaxial tensile tests and Mode I fracture tests, but similar to that in Mode II fracture tests. Thus, the energy release rate during SITs should be correlated with JIIC. Compared with previous studies, this new proposed method was more consistent with the actual damage mechanism and did not rely on the specific critical damage values. Experiments on SA508, SA533, 15CrMoR, and S30408 revealed that the maximum error from this energy release rate-based approach was no more than 13% when compared with their conventional counterparts (compact tension tests), and thus can meet the precision requirement of engineering applications.

scholarly journals Bonding of similar AA3105 aluminum alloy by Accumulative Roll Bonding process

2021 ◽  
Author(s):  
Mohamad El Mehtedi ◽  
Daniele Lai ◽  
Rayane Almehtedi ◽  
Mauro Carta ◽  
Pasquale Buonadonna ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Accumulative Roll Bonding ◽  
Sheet Thickness ◽  
Tensile Tests ◽  
Ultrafine Grain ◽  
Reinforced Composites ◽  
Final Thickness ◽  
Roll Bonding ◽  
Dissimilar Metal ◽  
Micro Cracks

Accumulative roll-bonding (ARB) is a novel plastic straining process aimed at bonding of similar and dissimilar metal combinations. Moreover, it is used recently to produce ultrafine grain materials and metal matrix reinforced composites to enhance mechanical, electrical, and corrosion resistance properties. This work presents an experimental study of roll bonding and accumulative roll bonding of similar AA3105 aluminum alloy at 300°C with a final thickness of 1.2 mm, focusing especially on bond strength evaluation and layers continuities. Tensile tests and three-points bending were performed to mechanical characterize the produced sheets in the various steps and based on the number of the cycles. The maximum strength was reached after 3 ARB cycles. After 4 cycles, the bonding interfaces have a uniform distribution through the sheet thickness, it is possible to distinguish only the interface formed in the last pass in the fracture surface, and no significant enhancement in strength was observed. Starting from 2 ARB cycles, micro-cracks were observed at the outer surface for bending angles greater than 90 deg, and at 180 deg all ARBed samples except A1 were failed.

Fracture Response of Fine-Grained Cement-Based Composite Specimens with Special Inclusions

2019 ◽  
Vol 292 ◽  
pp. 63-68 ◽  
Author(s):  
Michal Vyhlídal ◽  
Iva Rozsypalová ◽  
Tomáš Majda ◽  
Petr Daněk ◽  
Hana Šimonová ◽  
...  
Keyword(s):  
Transition Zone ◽  
Interfacial Transition Zone ◽  
Mechanical Fracture ◽  
Three Point Bending ◽  
Fine Grained ◽  
Fracture Parameters ◽  
Edge Notch ◽  
Fracture Tests ◽  
Materials Used ◽  
Bending Fracture

This paper concerns research into the importance of the interfacial transition zone around inclusions of selected materials in fine-grained cement-based composite. Tests were performed on eight sets of prismatic test specimens. The sets differed in the inclusion materials used, which were placed at midspan above the initial central edge notch. The first was a reference set without any inclusion, the second contained a steel inclusion, four more contained different types of rock inclusion, the seventh contained an inclusion of extruded polystyrene, and the last contained a space of the same dimensions as that occupied by the inclusions in sets 2 to 7. The test specimens were subjected to three-point bending fracture tests at the age of (usually) 28 days. The fracture response was analysed by means of fracture mechanics theory, and apparent mechanical fracture parameters (modulus of elasticity, fracture toughness and fracture energy) were evaluated. The conclusion shows that a possible relationship exists between the differences in the mechanical fracture parameters of specimens with/without an inclusion and the existence of the interfacial transition zone.

Evaluation of fracture resistance of ceramics: Edge fracture tests

2007 ◽  
Vol 33 (3) ◽  
pp. 315-320 ◽  
Author(s):  
George Gogotsi ◽  
Sergey Mudrik ◽  
Vasily Galenko
Keyword(s):  
Fracture Resistance ◽  
Edge Fracture ◽  
Fracture Tests

Effect of Machining Process on Stable Crack Growth

2009 ◽  
Author(s):  
Abdel-Hamid I. Mourad ◽  
Aladdin Abu-Assi
Keyword(s):  
Crack Growth ◽  
Stable Crack Growth ◽  
Tensile Tests ◽  
Compact Tension ◽  
Machining Process ◽  
Fracture Test ◽  
Growth Behaviour ◽  
Crack Growth Behaviour ◽  
Normal Specimen ◽  
Fracture Tests

This paper aims to present an experimental evidence of the effect of machining process on stable crack growth behaviour (SCG) through AISI 4340 low alloy steel. Brittle fracture behaviour had been discovered in a batch of compact tension CT specimens, unlike previous batches that had shown ductile (stable crack growth) behaviour. This was unexpected, and indeed, was anomalous. An investigation was thus carried out to understand what processes that have affected the behaviour. Such anomalous brittle behaviour was observed while performing the fracture test on the affected specimen. The load-load displacement (P-ΔLL) curves show that the “normal” specimen exhibiting stable crack growth and the non-linear region, in the anomalous curve of the anomalous specimens, is rather limited. This indicates very limited, if any, stable crack growth. Fracture tests were carried out on CT specimens with different heat treatments to find the cause of this unexpected embrittlement. Microhardness measurements, tensile tests and microscopic (SEM) examination were also carried out and reported. The results suggest that, a great attention is needed during machining process to avoid accidental changes in the properties and to avoid misleading experimental results.

Degradation Mechanism of Dissimilar Metal Weld Joints on Steam Generator Collectors VVER 440MW Type

2017 ◽  
Vol 741 ◽  
pp. 134-137
Author(s):  
Lubomír Junek ◽  
Ladislav Jurasek ◽  
Zdeněk Čančura ◽  
Miroslava Ernestová ◽  
Zuzana Skoumalová
Keyword(s):  
Steam Generator ◽  
Experimental Analysis ◽  
Degradation Mechanism ◽  
Steam Generators ◽  
Dissimilar Metal ◽  
Weld Joints ◽  
Dissimilar Metal Weld ◽  
Metal Weld

Indications were detected on dissimilar metal welds (DMW) of steam generators (SG) after 20 years of operation during NDT inspections. Indications started slowly growth every year. DMW on SGs had to be repaired. Paper describes experimental analysis and degradation mechanism of SG weld joints failures.

On the Use of the Notch Master Curve for Apparent Fracture Toughness Predictions of Notched Ferritic Steels Operating Within the Ductile-to-Brittle Transition Zone

2015 ◽  
Author(s):  
Sergio Cicero ◽  
Tiberio Garcia ◽  
Virginia Madrazo
Keyword(s):  
Fracture Toughness ◽  
Transition Zone ◽  
Fracture Resistance ◽  
Master Curve ◽  
Ferritic Steels ◽  
Brittle Transition ◽  
Apparent Fracture Toughness ◽  
Different Temperatures ◽  
Fracture Tests ◽  
Ductile To Brittle Transition

This paper presents the Notch-Master Curve as a model for the prediction of the apparent fracture toughness of ferritic steels in notched conditions and operating at temperatures corresponding to their ductile-to-brittle transition zone. The Notch-Master Curve combines the Master Curve of the material in cracked conditions and the notch corrections provided by the Theory of Critical Distances. In order to validate the model, the fracture resistance results obtained in fracture tests performed on notched CT and SENB specimens are presented. The results gathered here cover four ferritic steels (S275JR, S355J2, S460M and S690Q), three different notch radii (0.25 mm, 0.50 mm and 2.0 mm) and three different temperatures within the corresponding ductile-to-brittle transition zone. The results demonstrate that the Notch Master Curve provides good predictions of the fracture resistance in notched conditions for the four materials analyzed.

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