Characterization of Weld Metal Deposited With a Self Shielded Flux Cored Electrode for Pipeline Girth Welds and Offshore Structures

2010 ◽  
Author(s):  
Badri K. Narayanan ◽  
Lisa McFadden ◽  
M. J. Mills ◽  
Marie A. Quintana
Keyword(s):  
Electron Microscopy ◽  
Weld Metal ◽  
Carbon Content ◽  
Orientation Imaging Microscopy ◽  
Welding Process ◽  
Offshore Structures ◽  
Precipitation Process ◽  
Girth Welds ◽  
Precipitate Evolution

Pipeline girth welds deposited with a self-shielded flux cored electrode process (FCAW-S) have been characterized to assess the effect of micro-alloying elements on microstructure and precipitate evolution and correlate it to strength and toughness. A 2.0 mm diameter electrode was used to deposit weld metal in a 12.7 mm thick API grade X-70 pipe joint. The weld metal properties were characterized and shown to overmatch the pipe. The DBTT of the weld metal has been determined through Charpy V-Notch toughness measurements. The effect of heat input and welding procedure has been assessed over a range of heat inputs (1–1.5 kJ/mm.). The effect of dilution from the base plate on toughness has been assessed by measuring the sensitivity of weld metal toughness to changes in carbon content. The as-welded region of the weld has been characterized using different characterization techniques. Ferritic weld metal deposited with a self-shielded arc welding process has intentional additions of aluminum, magnesium, titanium and zirconium. This results in a complex precipitation process that has been characterized with a combination of electron microscopy techniques. The effect of micro-alloying additions on the variant selection during the austenite to ferrite transformation and microstructure evolution has been studied with electron back scattered diffraction (EBSD) in conjunction with orientation imaging microscopy (OIM). Transmission electron microscopy (TEM) was used to characterize the precipitate evolution in these welds. The evidence shows that the formation of a spinel oxide is critical for the nucleation of nitrides of zirconium and titanium and prevents the agglomeration of aluminum rich oxides and the formation of large aluminum nitrides. The evolution of precipitate formation is critical to limit large inclusions and improve weld metal toughness. The presence of titanium and zirconium increases the fraction of high angle grain boundaries within the microstructure resulting in increased resistance to crack propagation. The characterization of the microstructures at two different carbon contents indicates the greater propensity to form twin related variants with increase in carbon content. This suggests a lower transformation temperature of austenite and may be the reason for poor toughness.

Tensile and Toughness Properties of Pipeline Girth Welds

2006 ◽  
Author(s):  
J. A. Gianetto ◽  
J. T. Bowker ◽  
R. Bouchard ◽  
D. V. Dorling ◽  
D. Horsley
Keyword(s):  
Weld Metal ◽  
Welding Process ◽  
Strain Curve ◽  
High Strength ◽  
Primary Objective ◽  
Stress Strain ◽  
Line Pipe ◽  
Arc Welding Process ◽  
Girth Welds ◽  
Metal Microstructure

The primary objective of this study was to develop a better understanding of all-weld-metal tensile testing using both round and strip tensile specimens in order to establish the variation of weld metal strength with respect to test specimen through-thickness position as well as the location around the circumference of a given girth weld. Results from a series of high strength pipeline girth welds have shown that there can be considerable differences in measured engineering 0.2% offset and 0.5% extension yield strengths using round and strip tensile specimens. To determine whether or not the specimen type influenced the observed stress-strain behaviour a series of tests were conducted on high strength X70, X80 and X100 line pipe steels and two double joint welds produced in X70 linepipe using a double-submerged-arc welding process. These results confirmed that the same form of stress-strain curve is obtained with both round and strip tensile specimens, although with the narrowest strip specimen slightly higher strengths were observed for the X70 and X100 linepipe steels. For the double joint welds the discontinuous stress-strain curves were observed for both the round and modified strip specimens. Tests conducted on the rolled X100 mechanized girth welds established that the round bar tensile specimens exhibited higher strength than the strip specimens. In addition, the trends for the split-strip specimens, which consistently exhibit lower strength for the specimen towards the OD and higher for the mid-thickness positioned specimen has also been confirmed. This further substantiates the through-thickness strength variation that has been observed in other X100 narrow gap welds. A second objective of this study was to provide an evaluation of the weld metal toughness and to characterize the weld metal microstructure for the series of mechanized girth welds examined.

Case Study on LBB Application for Field Fabrication Weld Metal of Nuclear Primary Piping Systems

2003 ◽  
Author(s):  
K. C. Kim ◽  
J. T. Kim ◽  
J. I. Suk ◽  
H. K. Kwon ◽  
U. H. Sung ◽  
...  
Keyword(s):  
Weld Metal ◽  
Carbon Content ◽  
Arc Welding ◽  
Filler Metal ◽  
Welding Process ◽  
Test Results ◽  
Fracture Characteristics ◽  
Reactor Coolant ◽  
Piping Systems ◽  
Arc Welding Process

In order to apply leak before break (LBB) design for nuclear primary piping systems, dynamic and static J-R tests of field fabrication weld metal were carried out to determine mechanical properties at 316°C. For the reactor coolant piping system made by SMAW (Shielded Metal Arc Welding) process of the SA508 Cl.1a, the variation of J-R fracture characteristics with the loading rate of 1mm/min and 1,000mm/min was examined to prevent the catastrophic break under seismic loading. In the J-R test results, the J-R curves at 1,000mm/min are about 60% higher than those at 1mm/min. It suggests that the welding joints of the reactor coolant piping may be susceptible to dynamic strain aging at 316°C. For the surge line piping made by GTAW (Gas Tungsten Arc Welding) process of the SA312 TP347, excellent static J-R properties are required because the nominal diameter of the pipe is relatively small size of 12 inch. In order to examine the effect of carbon content in the filler metal on the fracture toughness of its welded metal, weld metal specimens were made by using 3 kinds of filler metals whose carbon contents were 0.050, 0.030 and 0.025%, respectively. In the static J-R test results, weld metal made by one of three electrodes satisfied the LBB acceptance criteria. Much better J-R fracture characteristics with decreasing carbon content of filler metal can be shown.

The influence of the carbon addition on the microstructure of a U-Nb alloy and the features of Nb2C inclusions

2018 ◽  
Vol 115 (3) ◽  
pp. 309 ◽  
Author(s):  
Dong Chen ◽  
Rong Ma ◽  
Xianglin Chen ◽  
Zhenhong Wang ◽  
Bin Su ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Carbon Content ◽  
Size Distribution ◽  
Carbon Addition ◽  
X Ray ◽  
Average Grain Size ◽  
Inclusion Morphology ◽  
Spectroscopy Optical ◽  
Scanning Electron

The effects of the carbon addition on the morphology, composition, size distribution and formation mechanism of inclusions in a U-5.5 Nb alloy were discussed. The influence of the carbon content on the microstructure and hardness were also investigated. The methods used in the present study were scanning electron microscopy coupled with energy dispersive X-ray spectroscopy, optical microscopy, and hardness measurements. The results show that the carbon content obviously affects the morphology, size distribution and area fraction of the Nb2C inclusions. Moreover, characterization of the inclusion morphology shows that the Nb2C inclusions form in the liquid and subsequently grow, collide and agglomerate to form clusters. Meanwhile, the average grain size significantly decreases, and the hardness increases with increasing carbon content in the U-5.5 Nb alloy.

Mechanical Properties and Microstructure of Weld Metal and HAZ Regions in X100 Single and Dual Torch Girth Welds

2010 ◽  
Author(s):  
James Gianetto ◽  
William Tyson ◽  
Yong-Yi Wang ◽  
John Bowker ◽  
Dong-Yeob Park ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Tensile Strength ◽  
Weld Metal ◽  
Welding Process ◽  
T Test ◽  
Fusion Line ◽  
Small Scale ◽  
Single Edge ◽  
Testing Procedures ◽  
Girth Welds

The main objectives of the current study were to further develop tensile and toughness testing protocols and to provide a better understanding of the factors that control both weld metal and HAZ microstructure and properties in pipeline girth welds. In this investigation, two series of rolled (1G) girth welds were made in X100 pipe of 36 in. diameter and 0.750 in. wall thickness using two pulsed-gas metal arc welding process variants: single and dual torch. The small-scale testing program included evaluations of all-weld-metal tensile strength, Charpy impact and standard fracture toughness measured by single-edge bend SE(B) tests, along with preliminary fracture toughness results using a single-edge tension SE(T) test developed at CANMET. Additional information was obtained from detailed microstructural characterizations of weld metal and HAZ regions along with microhardness testing. All-weld-metal tensile tests using round and strip tensile specimens showed variations with through-thickness location and in some case with clock position. Full stress-strain curves were generated, and 0.2% offset yield strength, flow stress, ultimate tensile strength, and uniform strain were measured and compared with pipe properties using calculated weld strength mismatch factors based on these properties. Charpy V-notch transition curves were generated for both weld metal and HAZ (notched within 0.5 mm of the fusion line). Fracture toughness of both weld metal and HAZ regions of single torch welds was assessed using standard SE(B) testing procedures with Bx2B preferred specimens notched through–thickness at the weld centerline and in the HAZ (within 0.5 mm of the fusion line). Full J-resistance curves were measured using SE(T) tests of surface-notched WM and HAZ specimens; the SE(T) test was designed to match the constraint of full-size pipeline girth welds.

Characterization of Rare-Earth Fluoride Anti-Stokes Phosphors by Scanning arid Transmission Electron Microscopy

1971 ◽  
Vol 29 ◽  
pp. 142-143
Author(s):  
N. M. P. Low ◽  
L. E. Brosselard
Keyword(s):  
Electron Microscopy ◽  
Rare Earth ◽  
Elevated Temperatures ◽  
Stoichiometric Composition ◽  
Rare Earth Ions ◽  
Crystalline Solid ◽  
Precipitation Process ◽  
Rare Earth Fluoride ◽  
Earth Fluoride ◽  
Rare Earth Fluorides

There has been considerable interest over the past several years in materials capable of converting infrared radiation to visible light by means of sequential excitation in two or more steps. Several rare-earth trifluorides (LaF3, YF3, GdF3, and LuF3) containing a small amount of other trivalent rare-earth ions (Yb3+ and Er3+, or Ho3+, or Tm3+) have been found to exhibit such phenomenon. The methods of preparation of these rare-earth fluorides in the crystalline solid form generally involve a co-precipitation process and a subsequent solid state reaction at elevated temperatures. This investigation was undertaken to examine the morphological features of both the precipitated and the thermally treated fluoride powders by both transmission and scanning electron microscopy.Rare-earth oxides of stoichiometric composition were dissolved in nitric acid and the mixed rare-earth fluoride was then coprecipitated out as fine granules by the addition of excess hydrofluoric acid. The precipitated rare-earth fluorides were washed with water, separated from the aqueous solution, and oven-dried.

Characterization of Tamm-Horsfall Urinary Glycoprotein

1973 ◽  
Vol 31 ◽  
pp. 420-421
Author(s):  
John P. Robinson ◽  
J. David Puett
Keyword(s):  
Electron Microscopy ◽  
Circular Dichroism ◽  
Secondary Structure ◽  
Quaternary Structure ◽  
Normal Adult ◽  
Morphological Properties ◽  
Adult Males ◽  
Circular Dichroïsm ◽  
Urinary Glycoprotein

Much work has been reported on the chemical, physical and morphological properties of urinary Tamm-Horsfall glycoprotein (THG). Although it was once reported that cystic fibrotic (CF) individuals had a defective THG, more recent data indicate that THG and CF-THG are similar if not identical.No studies on the conformational aspects have been reported on this glycoprotein using circular dichroism (CD). We examined the secondary structure of THG and derivatives under various conditions and have correlated these results with quaternary structure using electron microscopy.THG was prepared from normal adult males and CF-THG from a 16-year old CF female by the method of Tamm and Horsfall. CF female by the method of Tamm and Horsfall.

Electron Microscopic Detection and Characterization of Nonhuman Primate Enteric Viruses

1982 ◽  
Vol 40 ◽  
pp. 306-307
Author(s):  
G. C. Smith ◽  
R. L. Heberling ◽  
S. S. Kalter
Keyword(s):  
Electron Microscopy ◽  
Animal Model ◽  
Nonhuman Primate ◽  
Clinical Condition ◽  
Intestinal Tract ◽  
Enteric Viruses ◽  
Electron Microscopic ◽  
Microscopic Detection

A number of viral agents are recognized as and suspected of causing the clinical condition “gastroenteritis.” In our attempts to establish an animal model for studies of this entity, we have been examining the nonhuman primate to ascertain what viruses may be found in the intestinal tract of “normal” animals as well as animals with diarrhea. Several virus types including coronavirus, adenovirus, herpesvirus, and picornavirus (Table I) were detected in our colony; however, rotavirus, astrovirus, and calicivirus have not yet been observed. Fecal specimens were prepared for electron microscopy by procedures reported previously.

Electron Microscope Study of RNA's of Paramyxoviruses

1972 ◽  
Vol 30 ◽  
pp. 196-197
Author(s):  
Ruchama Baum ◽  
J.T. Seto
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Electron Microscope Study ◽  
Sendai Virus ◽  
Sodium Dodecyl ◽  
Rna Molecules ◽  
Virus Particles ◽  
Molecular Weights ◽  
Length Measurements

The ribonucleic acid (RNA) of paramyxoviruses has been characterized by biochemical and physiochemical methods. However, paramyxovirus RNA molecules have not been studied by electron microscopy. The molecular weights of these single-stranded viral RNA molecules are not known as yet. Since electron microscopy has been found to be useful for the characterization of single-stranded RNA, this investigation was initiated to examine the morphology and length measurements of paramyxovirus RNA's.Sendai virus Z strain and Newcastle disease virus (NDV), Milano strain, were used. For these studies it was necessary to develop a method of extracting RNA molecules from purified virus particles. Highly purified Sendai virus was treated with pronase (300 μg/ml) at 37°C for 30 minutes and the RNA extracted by the sodium dodecyl sulfate (SDS)-phenol procedure.

Application of solid-phase immune electron microscopy to study physical and stability characteristics of enterically transmitted non-a, non-b hepatitis virus

1988 ◽  
Vol 46 ◽  
pp. 80-81
Author(s):  
Charles D. Humphrey ◽  
E. H. Cook ◽  
Karen A. McCaustland ◽  
Daniel W. Bradley
Keyword(s):  
Electron Microscopy ◽  
Hepatitis A ◽  
Hepatitis A Virus ◽  
Solid Phase ◽  
Etiologic Agent ◽  
World Health ◽  
Health Concern ◽  
Morphological Identification ◽  
Immune Electron Microscopy

Enterically transmitted non-A, non-B hepatitis (ET-NANBH) is a type of hepatitis which is increasingly becoming a significant world health concern. As with hepatitis A virus (HAV), spread is by the fecal-oral mode of transmission. Until recently, the etiologic agent had not been isolated and identified. We have succeeded in the isolation and preliminary characterization of this virus and demonstrating that this agent can cause hepatic disease and seroconversion in experimental primates. Our characterization of this virus was facilitated by immune (IEM) and solid phase immune electron microscopic (SPIEM) methodologies.Many immune electron microscopy methodologies have been used for morphological identification and characterization of viruses. We have previously reported a highly effective solid phase immune electron microscopy procedure which facilitated identification of hepatitis A virus (HAV) in crude cell culture extracts. More recently we have reported utilization of the method for identification of an etiologic agent responsible for (ET-NANBH).

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