|Title of Invention||
A FLUX CORED ELECTRODE AND A METHOD OF ARC WELDING EMPLOYING THE SAME
|Abstract||The present invention relates to a flux cored electrode having a sheath and core materials in the metal sheath, said core materials including barium fluoride, lithium fluoride, lithium oxide and iron oxide, said core materials including up to 55 weight percent barium fluoride, 2-12 weight percent lithium fluoride, up to 15 weight percent lithium oxide, and 5-20 weight percent iron oxide, a weight ratio of a total weight percent of barium to a total weigh percent of lithium in said core materials is 8-12: 1 and also a method of arc welding employing the flux cored electrode.|
|Full Text||BARIUM AND LITHIUM RATIO FOR FLUX CORED ELECTRODE
The present invention relates to particular ratios of barium and lithium for flux cored electrodes such as used in a variety of arc welding processes.
5 BACKGROUND OF INVENTION
In the field of arc welding, the main types of welding processes are gas-metal arc welding with solid (GMAW) or metal cored wires (GMAW-C), gas shielded flux-cored arc welding (FCAW-G), self-shielded flux-cored arc welding (FCAW-S), shielded metal arc welding (SMAW) and submerged arc welding (SAW).
10 Metal cored electrodes are used increasingly as an alternative to solid wires
because of increased productivity during welding fabrication of structural components. Metal cored electrodes are composite electrodes consisting of a core (fill) material surrounded by a metallic outer sheath. The core consists mainly of iron powder and alloying and fluxing ingredients to help with arc stability, weld wetting
15 and appearance etc., such that the desired appearance and mechanical properties are obtained in the weld. Metal cored electrodes are manufactured by mixing the ingredients of the core material and depositing them inside a formed strip, and then closing and drawing the strip to the final diameter. Metal cored electrodes provide increased deposition rates and produce a wider, more consistent weld penetration
20 profile compared to solid electrodes. Moreover, they provide improved arc action, generate less fume and spatter, and provide weld deposits with better wetting compared to solid electrodes.
FCAW-S electrodes do not use any shielding during welding and protection of the weld metal from the ambient is achieved through the use of deoxidizers and
25 dentriders like Al, Mg, Ti and Zr. However, a certain ratio of barium to lithium is
often utilized in order to control the melting range and the fluidity of the slag and weld puddle. This ratio can be modified to render the electrode appropriate for welding out of position, i.e. either vertically up or vertically down. From ternary diagrams of barium, lithium and strontium fluorides, it is known that melting point is 5 generally reduced with increasing levels of lithium fluoride.
Although electrodes with barium and lithium compounds are known, a need still remains for electrode and resulting slag compositions that exhibit improved properties, particularly with respect to the proportions of barium and lithium and the flow characteristics of the slag and weld puddle properties resulting therefrom. 10
In a first aspect, the present invention provides a flux cored electrode in which the components of the core are chosen to produce a particular slag system. The core components include from about 35% to about 55% barium fluoride, and from about 15 2% to about 12% lithium fluoride.
In another aspect, the present invention provides a flux cored electrode comprising barium and lithium in a mass ratio of total barium to total lithium of from about 8:1 to about 12:1.
In yet another aspect, the present invention provides a slag system resulting 20 from a flux cored electrode, the slag system resulting from the presence of from about 35% to about 55% barium fluoride and from about 2% to about 12% lithium fluoride in the core of the electrode.
In yet another aspect, the present invention provides a method of arc welding
using a flux cored electrode. The method comprises providing a flux cored electrode
25 that produces a slag system resulting from the presence of (i) from about 35% to
about 55% barium fluoride and (ii) from about 2% to about 12% lithium fluoride in the core of the electrode. The method also comprises passing an electric current through the electrode to thereby produce the slag system.
In yet another aspect, the present invention provides a method of arc welding
5 using a flux cored electrode. The method comprises providing a flux cored electrode
that includes barium and lithium in a mass ratio of total barium to total lithium of
from about 8:1 to about 12:1. The method also comprises passing an electric current
through the electrode to thereby produce the slag system.
These and other objects and advantages will become apparent from the 10 following description.
The present invention is based upon a discovery that excellent properties in a resulting slag can be obtained if barium and lithium are utilized in certain proportions, 15 in the slag. Accordingly, various preferred embodiment slag systems, electrode compositions for forming such slag systems, and related methods of use are provided. A preferred electrode composition in accordance with the present invention comprises:
barium fluoride, as the barium source, from about 35 to about 55% of 20 the core material (by weight),
lithium fluoride, as the lithium source, from about 2 to about 12% of the core material (by weight),
barium carbonate, as a secondary barium source, from about 0 to about 8% of the core material (by weight),
lithium carbonate, as the secondary lithium source, from about 0 to about 8% of the core material (by weight) as lithium carbonate,
lithium oxide, from about 2 to about 15% of the core material,
iron oxide, from about 5 to about 20% of the core material,
5 calcium oxide, from about 0 to about 5% of the core material,
silicon oxide, from about 0 to about 5% of the core material,
manganese oxide, from about 0 to about 5% of the core material,
aluminum, magnesium, titanium, zirconium, or combinations thereof,
up to about 25% of the core material, for deoxidation and denitriding, and
10 the remaining core material including metallics such as, but not limited
to iron, nickel, manganese and/or silicon.
Preferably, a barium to lithium ratio from about 8:1 to about 12:1,
respectively, is utilized for optimum weldability and good operating range. This ratio
is the mass ratio of total barium to total lithium in the electrode. A ratio less than
15 about 8:1 will cause poor arc action while a ratio greater than about 12:1 will cause
poor voltage range and produce welds with porosity.
Set forth below in Table 1 is a representative core formulation of a flux cored electrode used for forming the preferred slag systems. All percentages in Table 1 are based upon the weight of the electrode core formulation, which in turn constitutes 20 about 20% of the electrode by weight.
The preferred embodiment slag systems and electrodes for forming such systems can employ a wide range of compounds used in the electrode for providing a source of barium in the resulting slag. For example, it is contemplated that barium monoferrate (BaFe2o4) and complexes of BaO, FeO3, CaO, SiO2, and/or TiO2 can be used in the electrode. Although generally less preferred due to its strong hygroscopic properties, BaO by itself, could in certain embodiments, be used in the electrode.
The preferred embodiment slag systems and electrodes for forming such systems can utilize a wide array of compounds used in the electrode for providing a source of lithium in the resulting slag. For example, it is contemplated that various complexes of Li2O, Fe2O3, MnO2, CaO, SiO2, and/or TiO2 can be used in the electrode. Although generally less preferred due to its strong hygroscopic properties, Li2O by itself, could in certain embodiments be used in the electrode.
The levels of barium and lithium fluoride were changed to evaluate the effect of these individual slag-making agents on arc stability and resistance to porosity. Automated weld tests at sequentially increasing voltages in the vertical down position
1212-che-2006 complete specification as granted.pdf
1212-CHE-2006 CLAIMS GRANTED.pdf
1212-CHE-2006 CORRESPONDENCE OTHERS.pdf
1212-CHE-2006 CORRESPONDENCE PO.pdf
1212-CHE-2006 POWER OF ATTORNEY.pdf
|Indian Patent Application Number||1212/CHE/2006|
|PG Journal Number||2/2010|
|Date of Filing||11-Jul-2006|
|Name of Patentee||LINCOLN GLOBAL,INC.|
|Applicant Address||14824 MARQUARDT AVENUE SANTA FE SPRINGS CALIFORNIA 90670 USA.|
|PCT International Classification Number||B23K35/36|
|PCT International Application Number||N/A|
|PCT International Filing date|