Covered Electrodes Temperature Variation During Wet Welding and Its Influence on Weld Metal Porosity

2005 ◽  
Author(s):  
Ezequiel C. P. Pessoa ◽  
Alexandre Q. Bracarense ◽  
Stephen Liu ◽  
Faustino Peres Guerrero ◽  
Eduardo M. Zica
Keyword(s):  
Mechanical Properties ◽  
Weld Metal ◽  
Tensile Tests ◽  
Mechanical Tests ◽  
Weld Bead ◽  
Electrode Temperature ◽  
Charpy Test ◽  
Underwater Wet Welding ◽  
Porosity Reduction ◽  
Covered Electrodes

The objective of this work was to evaluate the porosity variation along weld bead and its relation with weld metal mechanical properties and electrode heating during underwater wet welding. Three commercial covered electrodes were used to make bead-on-plate welds. V-groove welds were also made using two electrodes at 50 and 100 meters depth in three different steels. Electrode temperature and weld metal porosity measurements and mechanical tests were performed. The results of temperature measurements indicated that electrode temperature increases during underwater wet welding. Simultaneously, porosity reduces along the BOP and V-groove weld beads. Mechanical tests showed that the mechanical properties are better at the end of welds. Additionally, the load supported by side bend tests samples extracted from 50 meter welds were higher than that measured for the 100 meter welds. Tensile test results also showed similar trend. Charpy test did not reveal any relation between the absorbed energy and porosity reduction along weld bead. However presented the same trend of bend and tensile tests at 50 and 100 m depth.

Designing Shielded Metal Arc Consumables for Underwater Wet Welding in Offshore Applications

1995 ◽  
Vol 117 (3) ◽  
pp. 212-220 ◽  
Author(s):  
A. Sanchez-Osio ◽  
S. Liu ◽  
D. L. Olson ◽  
S. Ibarra
Keyword(s):  
Calcium Carbonate ◽  
Weld Metal ◽  
Acicular Ferrite ◽  
Oxide Formation ◽  
Electrode Coating ◽  
Microstructural Refinement ◽  
Underwater Wet Welding ◽  
High Toughness ◽  
Porosity Reduction ◽  
Grain Boundary Ferrite

The use of underwater wet welding for offshore repairs has been limited mainly because of porosity and low toughness in the resulting welds. With appropriate consumable design, however, it is possible to reduce porosity and to enhance weld metal toughness through microstructural refinement. New titanium and boron-based consumables have been developed with which high toughness acicular ferrite (AF) can be produced in underwater wet welds. Titanium, by means of oxide formation, promoted an increase in the amount of acicular ferrite in the weld metal, while boron additions decreased the amount of grain boundary ferrite (GBF), further improving the microstructure. Porosity reduction was possible through the addition of calcium carbonate at approximately 13 wt percent in the electrode coating. However, weld metal decarburization also resulted with the addition of carbonate.

Mechanical Properties of Steel Printed on Ceramics

2019 ◽  
Author(s):  
Seyed M. Allameh ◽  
Miguel Ortiz Rejon
Keyword(s):  
Mechanical Properties ◽  
3D Printing ◽  
Cross Sections ◽  
Heat Dissipation ◽  
Structural Integrity ◽  
Tensile Tests ◽  
Weld Bead ◽  
Cnc Machining ◽  
Main Question ◽  
Dog Bone

Abstract Construction industry is about to embrace 3D printing as a viable technology for fabricating structures that are not physically or commercially impractical. These include curved components that could be embedded in buildings. On the other hand, whole house building by 3D printing has been attempted around the world using giant concrete printers. The main question is how to integrate steel rebars in concrete by 3D welding and still maintain the structural integrity and reliability of the conventional rebars. To accomplish the incorporation of rebars in concrete, steel must be welded within concrete. Heat dissipation rates may be different in different directions when the 3D molten weld pool solidifies, especially when the substrate is concrete. This may affect the strength of the material along and across the weld bead. To investigate this effect, it is important to study the mechanical properties of 3D welded steel in the directions of length, thickness and width. Experiments conducted in this study include the 3D welding of steel on concrete tiles by attaching the torch of a MIG welder to a meter-scale 3D printer carriage. The weld beads were then cross sections in directions along the weld bead, across the bead and perpendicular to the ceramic substrate. Dog-bone shaped micro-scale samples were extracted along those direction by CNC machining and EDM milling. The specimens were then mounted on the grippers of a hybrid micro-tester and tensile tests were carried out. The results of the tests are reported, and the implications of the findings in terms of the feasibility of 3D printing of steel reinforced concrete are discussed.

Assessment of GFRP Mechanical Properties in Order to Determinate Suitability for UAV Components

2020 ◽  
Vol 834 ◽  
pp. 57-66
Author(s):  
Mihaela Raluca Condruz ◽  
Alexandru Paraschiv ◽  
Andreea Deutschlander ◽  
Ionel Mîndru
Keyword(s):  
Mechanical Properties ◽  
Epoxy Resin ◽  
Tensile Tests ◽  
Mechanical Tests ◽  
Low Velocity Impact ◽  
Small Range ◽  
Low Velocity ◽  
Damage Degree ◽  
Aerial Vehicle ◽  
Twill Weave

Mechanical properties of several composite materials were assessed in order to establish their suitability for unmanned aerial vehicle components manufacturing. The materials under evaluation consisted in E-glass fiber (satin/twill weave) impregnated with polyester, respective epoxy resin. The study was focused on two mechanical tests: low-velocity impact and tensile tests. Based on the results obtained, it was observed that configurations reinforced with twill weave presented higher tensile strength compared with satin reinforced configurations. Moreover, they presented a lower damage degree in case of impact tests. It was concluded that fabric quality has a considerable influence on the impregnation process and on the composite material mechanical properties. In the present case, the twill weave impregnated with epoxy resin can be used to manufacture small range UAV components.

Hydrogen Embrittlement for X-70 Pipeline Steel in High Pressure Hydrogen Gas

2015 ◽  
Author(s):  
Un Bong Baek ◽  
Hae Moon Lee ◽  
Seung Wook Baek ◽  
Seung Hoon Nahm
Keyword(s):  
Mechanical Properties ◽  
High Pressure ◽  
Pipeline Steel ◽  
Fracture Morphology ◽  
Tensile Tests ◽  
Mechanical Tests ◽  
Hydrogen Gas ◽  
Reduction Of Area ◽  
Api 5L X70 Steel ◽  
Pressure Hydrogen

The tensile properties of API 5L X70 pipeline steels have been measured in a high-pressure (10 MPa) hydrogen gas environment. Significant decreases in elongation at failure and reduction of area were observed when testing in hydrogen as compared with air, and those changes were accompanied by noticeable changes in fracture morphology. The present paper exposes the changes in mechanical properties of a grade API 5L X70 steel through numerous mechanical tests, i.e. tensile tests, notch tensile tests, fracture toughness and fatigue crack growth measurements, performed either in atmosphere or in 10 MPa pressure of hydrogen gas.

Study of weld form and weld bead in bottom position at semi-automatic underwater wet welding

2021 ◽  
pp. 487-490
Author(s):  
V.A. Lebedev ◽  
D.N. Krazhanovsky
Keyword(s):  
Weld Metal ◽  
Experimental Research ◽  
Response Surfaces ◽  
Weld Bead ◽  
Regression Equations ◽  
Underwater Wet Welding ◽  
Electrode Wire ◽  
Bottom Position ◽  
Pulse Feed ◽  
Contour Plots

Some features of underwater mechanized and automatic wet welding with pulse feed of the electrode wire are considered. The conditions for experimental research to identify the parameters of forming of the weld metal at different parameters of pulse feed of the electrode wire are described. Regression equations describing the dependences of the size of the roll on the parameters of pulse feed and contour plots and response surfaces of the marked dependences are presented.

Thermoplastic polyurethanes for mining application processing by 3D printing

2019 ◽  
Vol 1 (95) ◽  
pp. 13-19
Author(s):  
M. Mrówka ◽  
M. Szymiczek ◽  
J. Lenża
Keyword(s):  
Mechanical Properties ◽  
3D Printing ◽  
Mine Water ◽  
Aging Process ◽  
Tensile Tests ◽  
Mechanical Tests ◽  
Printing Technology ◽  
Thermoplastic Polyurethanes ◽  
3D Printing Technology ◽  
Static Tensile

Purpose: Thermoplastic polyurethanes (TPU) found application in mining. Due to the excellent processing properties, thermoplastic polyurethanes can be also use to make elements that would facilitate miner's work. These elements, however, differ in dimensions depending on the person who is going to use them, that is why they should be personalized. In case of all the above studies, the elements or stuffs were made by means of the injection method. This method limits the possibility of producing mining’s stuff only to models that have a mould. The 3D printing technology developing rapidly throughout the recent years allows for high-precision, personalized elements’ printing, made of thermoplastic materials. Design/methodology/approach: The samples from thermoplastic polyurethanes were made using 3D printing and then subjected to the aging process at intervals of 2, 7 and 30 days. The samples were then subjected to a static tensile tests, hardness tests and FT-IR spectroscopy. Findings: The obtained results of mechanical tests and IR analyses show that the aging process in mine water does not affect the mechanical properties of the samples regardless of the aging time. IR spectral analysis showed no changes in the structure of the main and side polyurethane chains. Both mechanical and spectral tests prove that polyurethanes processed using 3D printing technology can be widely used in mining. Research limitations/implications: Only one type of TPU was processed in this work. Further work should show that synthetic mine water does not degrade the mechanical properties of other commercially available TPUs. Practical implications: The additive technology allows getting elements of mining clothing, ortheses, insoles or exoskeleton elements adapted to one miner. Originality/value: The conducted tests allowed to determine no deterioration of the mechanical properties of samples aged in synthetic mine water. TPU processing using 3D printing technology can be used in mining.

Microstructure and mechanical properties of specimens produced using the wire-arc additive manufacturing process

2019 ◽  
pp. 095440621988332
Author(s):  
A Astarita ◽  
G Campatelli ◽  
P Corigliano ◽  
G Epasto ◽  
F Montevecchi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Tensile Tests ◽  
Mechanical Tests ◽  
Image Correlation ◽  
Correlation Technique ◽  
Layer Stacking ◽  
Static Tensile ◽  
X Ray Computed ◽  
Wire Arc Additive Manufacturing

The additive manufacturing technique is becoming popular and promising in recent years. Some steel ER70S-6 specimens were produced by wire arc additive manufacturing. Before the tensile tests, 3D X-ray computed tomography was applied to detect the presence of internal defects due to the production process. Static tensile tests were performed in order to analyze the influence of the different directions (deposition and layer stacking directions) on the mechanical properties. The digital image correlation technique was applied during the tests for detecting the displacement and strain fields, while infrared thermography was applied for detecting the temperature field of the specimen surface. After the mechanical tests, scanning electron microscopy was employed to analyze the fracture surfaces of the specimens. The results showed the presence of small defects that did not affect the mechanical properties of the specimens and no significant anisotropy was detected in the two directions (deposition and layer stacking directions).

scholarly journals Morphology and mechanical properties of polypropylene-wood flour composites

BioResources ◽  
2006 ◽  
Vol 1 (2) ◽  
pp. 209-219 ◽  
Author(s):  
D. Dobreva ◽  
S. Nenkova ◽  
St. Vasileva
Keyword(s):  
Mechanical Properties ◽  
Wood Flour ◽  
Tensile Tests ◽  
Mechanical Tests ◽  
Monochloroacetic Acid ◽  
X Ray Diffraction ◽  
Physical Strength ◽  
Positive Effects ◽  
Crystallization Degree ◽  
Modified Wood

The microstructure and mechanical properties of polymer composites based on polypropylene and wood flour modified with monochloroacetic acid were investigated. Scanning electron microscopy and wide-angle X-ray diffraction were used as methods to probe the composite microstructures, while the tensile test was used to measure the physical strength. The wood flour modification was performed at different levels of monochloroacetic acid, ranging from 0.01 to 1 mol, while the modified wood flour was used as filler for polypropylene at 10, 20 and 30 wt.-%. It was found that increasing the monochloroacetic acid fraction influences the microstructure of the composites and leads to more homogeneous products. The introduction of non-modified wood flour decreases the polypropylene crystallization degree, but it improves after introduction of monochloroacetic acid. Physical-mechanical tests showed positive effects on tensile tests and Charpy notched impact strength. The new composites appear to be promising materials for construction purposes.

Effect of Previous Grain Size on Recystallization Texture and the Formability of the Nb Ferritic Stainless Steel

2016 ◽  
Vol 879 ◽  
pp. 1594-1599
Author(s):  
Daniella Gomes Rodrigues ◽  
Cláudio Moreira Alcântara ◽  
Dagoberto Brandão Santos ◽  
Tarcísio Reis de Oliveira ◽  
Berenice Mendonça Gonzalez
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Stainless Steel ◽  
Ferritic Stainless Steel ◽  
Longitudinal Section ◽  
Tensile Tests ◽  
Mechanical Tests ◽  
Planar Anisotropy ◽  
Electron Backscattered Diffraction ◽  
R Value

The ferritic stainless steels are materials used in several segments due to the excellent combination of mechanical properties and corrosion resistance. The mechanical properties of these alloys are strongly dependent on the microstructural characteristics and crystallography texture. The aim of this experimental study is to investigate the roles of the grain size of the hot rolled sample on the development of the microstructure, texture and formability of ferritic stainless steel. The main elements of chemical composition of the steel under investigation were 16.0 %Cr, 0.021 %C, 0.024 %N and 0.35 %Nb. Coarse and fine grains samples were cold rolled up to 90% thickness reduction and annealed at 880°C with soaking time of the 24 s. The texture measurements were performed by Electron Backscattered Diffraction (EBSD) in the longitudinal section. The formability was evaluated by the R-value and planar anisotropy (Δr) in tensile tests. The final microstructure after annealed was more homogenous for smaller initial grain size sample. This condition was favorable to develop γ-fiber, with sharpness intensity in 111121 components. The highest R-value and smallest planar anisotropy was obtained for a {111}/{001} ratio around 5.37. On the other hand, coarser initial grain size sample had showed a heterogeneous microstructure and texture, performing badly in mechanical tests (anisotropy).

Influence of Nitrogen Gas of Three Different Procedures of GTAW Welding on Final Metallurgical and Mechanical Properties of a 2% W SDSS Piping

2005 ◽  
Author(s):  
Petroˆnio Z. Ju´nior ◽  
Paulo H. Alcaˆntara ◽  
Ricardo A. Fedele ◽  
Geraldo J. M. Paiva ◽  
Ney R. W. Chaves
Keyword(s):  
Mechanical Properties ◽  
Weld Metal ◽  
Chemical Properties ◽  
Gas Mixtures ◽  
Mechanical Tests ◽  
Secondary Phases ◽  
Nitrogen Gas ◽  
Pure Nitrogen ◽  
Pure Argon ◽  
Gtaw Process

Duplex stainless steels (DSS) are finding increased application on offshore process plants in Brazil. Welding them is always a challenge. Pure argon and argon/low-nitrogen gas mixtures are available for welding them with GTAW process. The use of the same kind of gases on shielding and backing is usual. If no nitrogen is present in the gas mixtures there may be loss of nitrogen from the weld metal or HAZ. Three different welding procedures were tested for a 2% tungsten superduplex parent metal to verify the loss of nitrogen from weld metal and HAZ. First procedure used a 2%N-88%Ar-10%He as the shielding mixture and pure Ar as the backing gas while the second one used pure Ar as shielding and pure nitrogen as backing gas. A third procedure with no nitrogen for shielding or backing was also carried out for comparisons. Chemical analyses, corrosion test and determination of austenite/ferrite content were done to check metallurgical and chemical properties. Mechanical tests were performed to compare mechanical properties of the weld metal and HAZ. ASME Code, section IX, plus Norsok standard M-601 were referenced. Results indicate good mechanical behavior, corrosion resistance and austenite/ferrite phases balance in both procedures that used nitrogen as one of the gases. The procedure using only pure argon showed a decrease of austenite content in weld metal and heat affected zone. However, it fulfilled all the requirements. They didn’t present secondary phases or very significant variances on austenite presence even on weld metal and HAZ.

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