Relationships between coating composition, all weld metal properties, operational behaviour, and diffusible hydrogen in weld metal from rutile electrodes of types ANSI/AWS A5.1–91 E6013 and E7024

1999 ◽  
Vol 4 (3) ◽  
pp. 133-142 ◽  
Author(s):  
E.S. Surian ◽  
N.M.R. de Rissone
Keyword(s):  
Weld Metal ◽  
Diffusible Hydrogen ◽  
Coating Composition ◽  
Metal Properties ◽  
Operational Behaviour

A New Method for Reducing Diffusible Hydrogen in Weld Metal

2012 ◽  
Author(s):  
Susan Fiore ◽  
Steve Barhorst ◽  
Mario Amata ◽  
Joe Bundy
Keyword(s):  
Weld Metal ◽  
Raw Materials ◽  
Shielding Gas ◽  
Feeding Problems ◽  
Diffusible Hydrogen ◽  
Flux Cored Arc Welding ◽  
Hydrogen Assisted Cracking ◽  
Wire Feeding ◽  
Metal Properties ◽  
Welding Consumables

The effect of hydrogen on weld metal and weld heat-affected zones (HAZ) has been well established over many years. The potential for hydrogen-assisted cracking increases as the strength of the steel increases. High fuel costs have driven the need for lower weights in the transportation and shipbuilding industries, and increased regulations have driven the need for higher safety factors in the pipeline industry. As a result, many industries are requiring higher and higher base metal strengths. The push for higher strength steels has resulted in an increased demand for ultra-low hydrogen welding consumables and processes. Manufacturers of flux-cored arc welding (FCAW) electrodes have generally attacked the problem of weld metal hydrogen through the use of raw materials that react with hydrogen to take it out of solution, by baking the wires in-process, and by using special drawing techniques and lubricants to minimize hydrogen pick-up. Unfortunately, many of the potential solutions result in electrodes that have poor operability, wire feeding problems, and/or increased welding fume. Hobart Brothers has recently developed a method of producing very low-hydrogen weld deposits, which utilizes fluorine-containing gas compounds in the weld shielding gas. The modified shielding gas has no effect on the weld metal properties or the operation of the welding electrodes. This paper provides details of the method, along with test results that have been achieved using a number of flux- and metal-cored electrodes representing a variety of American Welding Society (AWS) classifications.

A Predictive Electrochemical Model for Weld Metal Hydrogen Pickup in Underwater Wet Welds

1998 ◽  
Vol 120 (4) ◽  
pp. 243-248 ◽  
Author(s):  
R. C. de Medeiros ◽  
S. Liu
Keyword(s):  
Weld Metal ◽  
Hydrogen Content ◽  
Ferric Oxide ◽  
Welding Parameters ◽  
Oxide Content ◽  
Metal Interface ◽  
Feed System ◽  
Diffusible Hydrogen ◽  
Hydrogen Pickup ◽  
Electrochemical Model

Weld metal hydrogen pickup in underwater wet welding is severe due to the presence and dissociation of water surrounding the welding arc. This undesirable behavior can be minimized, however, with the use of oxidizing-type electrodes. The purpose of this investigation has been placed on the fundamental understanding of the effect of hydrogen pickup by the slag on the weld metal diffusible hydrogen content in direct current, shielded metal arc welding (SMAW) for both electrode-positive polarity (DCEP), and electrode-negative polarity (DCEN). To accomplish this purpose, 20 experimental oxidizing electrodes containing systematic ferric oxide (Fe2O3) additions, ranging from 0 to 70 wt. percent, to the flux coating were investigated. The mole fraction ratio of CaO/SiO2 in the fluxes ranged from 0.05 to 0.35, independent of the ferric oxide additions. Underwater, bead-on-plate welds were deposited on ASTM A36 steel coupons at 0.27 m (city) water depth using a gravity feed system. Welding parameters were held constant throughout the experiments. Weld metal diffusible hydrogen content was determined using the mercury displacement method according to current AWS standard. To correlate weld metal hydrogen content with slag chemistry, the slag hydrogen contents were also determined. The measured diffusible hydrogen contents showed that Fe2O3 was effective in reducing weld metal hydrogen content. Higher hydrogen values were always related to lower Fe2O3 contents initially present in the flux, for instance, 71 mL/100g (DCEP − 0 wt. percent Fe2O3) as compared to 31 mL/100g (DCEP − 36 wt. percent Fe2O3). Amazingly, diffusible hydrogen as low as 13 mL/100g was obtained with the use of DCEN polarity along with 53 wt. percent Fe2O3 in the flux coating. X-ray diffraction (XRD) conducted on different slags showed that the lower diffusible hydrogen values were always associated with the presence of fayalite (2FeO·SiO2). Complementing XRD analysis, Mo¨ssbauer spectroscopy analyses carried out on different slags showed that all ferric (Fe3+) oxide initially present in the slags had transformed to ferrous oxide (FeO), free or combined. Chemical analyses showed that weld metal hydrogen pickup was strongly dependent on the solubility of water in the slag systems. The total and diffusible hydrogen content in the weld metal increased monotonically with increasing slag hydrogen content. Finally, variations in weld metal hydrogen as well as slag hydrogen content with both polarity and iron oxide content in the slag were successfully predicted using an electrochemical model that describes the slag/metal interface equilibrium. In this investigation, the slag/metal interface has been identified as responsible in controlling the weld metal hydrogen pickup. The model assumed that hydrogen was present in the slag as (OH)− ions and that FeO displayed ideal solution behavior.

The effect of welding process and shielding atmosphere on the AlMg4.5Mn weld metal properties

2013 ◽  
Vol 104 (1) ◽  
pp. 18-25 ◽  
Author(s):  
Radica Prokić Cvetković ◽  
Olivera Popović ◽  
Meri Burzić ◽  
Radomir Jovičić ◽  
Sandra Kastelec Macura ◽  
...  
Keyword(s):  
Weld Metal ◽  
Welding Process ◽  
Metal Properties

Surfacing weld metal properties of aluminium alloys with Al‐Cu cored wire: Surfacing of aluminium alloys (3rd report)

1994 ◽  
Vol 8 (8) ◽  
pp. 623-629
Author(s):  
Y Kanbe ◽  
Y Nakada ◽  
S Kurihana ◽  
H Koike ◽  
T Miyake
Keyword(s):  
Weld Metal ◽  
Aluminium Alloys ◽  
Cored Wire ◽  
Metal Properties

Weld Metal Hydrogen Cracking in Transmission Pipelines Construction

2010 ◽  
Author(s):  
Sheida Sarrafan ◽  
Farshid Malek Ghaini ◽  
Esmaeel Rahimi
Keyword(s):  
Weld Metal ◽  
Construction Projects ◽  
High Strength Steels ◽  
High Strength ◽  
Carbon Equivalent ◽  
Transverse Cracks ◽  
Diffusible Hydrogen ◽  
Hydrogen Cracking ◽  
Girth Welds ◽  
Welding Position

Developments of high strength steels for natural gas pipelines have been in the forefront of steelmaking and rolling technology in the past decades. However, parallel to such developments in steel industry, the welding technology especially with regards to SMAW process which is still widely used in many projects has not evolved accordingly. Decreasing carbon equivalent has shifted the tendency of hydrogen cracking from the HAZ to the weld metal. Hydrogen cracking due to its complex mechanism is affected by a range of interactive parameters. Experience and data gained from field welding of pipeline construction projects indicated that weld metal hydrogen cracking is related to welding position as it occurs more in the 6 o’clock position of pipeline girth welds. In this research an attempt is made to open up the above observation in order to investigate the contributory factors such as welding position and welding progression in terms of diffusible hydrogen and possibly residual stress considerations. It was observed that transverse cracks produced in laboratory condition may not be detected by radiography. But, the higher tendency for cracking at 6 o’clock position was confirmed through bend test. It is shown that more hydrogen can be absorbed by the weld metal in the overhead position. It is shown that welding progression may also have a significant effect on cracking susceptibility and it is proposed that to be due to the way that weld residual stresses are developed. The observations can have an important impact on planning for welding procedure approval regarding prevention of transverse cracking in pipeline girth welds.

Investigation on Deposited Metal Properties of Homemade Nickel and Nickel-Free Electrodes and Fluxes for Submerged Arc Welding of SA-508 Gr.3 Cl.1

2017 ◽  
Author(s):  
Le Mei ◽  
Junbao Zhang ◽  
Yifeng Huang ◽  
Yan Yu ◽  
Yong Jiang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Weld Metal ◽  
Arc Welding ◽  
Proton Irradiation ◽  
Submerged Arc Welding ◽  
Impact Property ◽  
Welding Material ◽  
Weld Metals ◽  
Metal Properties ◽  
Submerged Arc

Up to now, two kinds of filler metal with or without nickel element for submerged arc welding have been largely used in the reactor pressure vessel (RPV) manufacturing. In order to study the effect of nickel element on weld metal properties of SA-508 Gr.3 Cl.1, submerged arc welding material with nickel (AWS classification F8P4-EGN-F2N, F2 for short) and welding material without nickel (F8P4-EA3N-A3N, A3 for short) were used; and conventional mechanical properties, low-cycle fatigue test, and proton irradiation analysis of the two weld metals were studied. Results show that the mechanical properties of the two different weld metals are similar, except that the Charpy V-notch impact property of the weld metal with nickel is better than that without nickel; the micro-structures of F2 and A3 weld metals are both composed of ferrite base and granular bainite, but the columnar grain size of F2 weld metal is smaller relatively, which results in better impact property. In addition, the irradiated A3 weld metal has fewer dislocation loops than the irradiated F2 weld metal after the same proton irradiation dose; the irradiated weld metals both have higher micro-Vickers hardness than before.

Girth Weld Qualification for High Strain Pipeline Applications

2005 ◽  
Author(s):  
Martin W. Hukle ◽  
Agnes M. Horn ◽  
Douglas S. Hoyt ◽  
James B. LeBleu
Keyword(s):  
Plastic Strain ◽  
Weld Metal ◽  
Heat Affected Zone ◽  
High Strain ◽  
Flaw Size ◽  
Small Scale ◽  
Plastic Strains ◽  
Strain Capacity ◽  
Metal Properties ◽  
Girth Welds

Pipeline applications that are subject to global plastic strains require specific testing and qualification programs intended to verify the strain capacity of the girth welds. Such strain demands are generally beyond the limits of standard ECA applicability which normally cover demands up to 0.5% strain. Therefore, qualification of welding procedures for high strain environments require significantly more testing than weld procedures intended for stress-based designs. The plastic strain capacity of girth welds is a function of the pipe and weld metal properties, as well as the maximum flaw size allowable in the girth weld. Specific weld metal/heat affected zone properties, based on small scale testing, should be combined with full scale curved wide plate testing of girth welds that include artificial flaws.

scholarly journals Engineered Weld Design: Are Composite Welds Likely in the Future?

2008 ◽  
Vol 580-582 ◽  
pp. 307-310 ◽  
Author(s):  
D.L. Olson ◽  
Young Do Park ◽  
S. Liu ◽  
J.E. Jackson ◽  
A.N. Lasseigne-Jackson ◽  
...  
Keyword(s):  
Weld Metal ◽  
Welding Process ◽  
Potential Method ◽  
Structural Features ◽  
Gas Composition ◽  
Metal Solidification ◽  
High Toughness ◽  
Low Temperature Creep ◽  
Metal Properties ◽  
Welding Consumables

Utilizing alternating welding process parameters, deposition practices, and welding consumables, particularly during multiple pass welding, it is possible to improve a variety of weld metal properties. There are available a number of phenomena occurring during welding that allow weld metal designers the ability to generate macro- and micro-structural features amenable to implementation of composite theory. These phenomena include solidification microsegregation during dendrite growth, gas-metal reactions between the selected alternating shielding gas composition and weld pool, and solidification microstructural orientation during welding. Additional methods of producing composite welds including specially designed weld compositions, weld metal solidification modification by arc pulsing, and dual wire deposition may be utilized to achieve single pass and multipass composite weld metal deposition. Composite welds are a potential method to solve challenging demands such as high-toughness at low temperature, creep strength at high temperature, and customized design for corrosion, wear, or cracking resistance.

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