US2051775A - Flux-coated electrode - Google Patents

Description

All@ 18, 1936. H. R. PENNINGTQN OSL-775 FLUX coATED ELEcTRonE Filed April 1o, 1934 ,a 0) and @diam d/'ce i deaqraby with Y1/00d )150566 jarra-mazyefzedg mad ym arabic,

i Patented Aug. 18, 1936 UNITED STATES PATENT No-FFICE.l

FLUX-conan ELEc'rnonn Application April lil, 1934, Serial-No. 119,847

2 claims.. (ci. 2119-8) It is the object of my invention to produce a ux-coated electrode or weld-rod in which the iiux-coating not only facilitates the welding peration and protects the welding during its mak- 5 ing and forms only an easily removable. slag, but' also one in which such flux coating is made of readily obtainable and inexpensive materials.

In arc welding, asis well known, it is desirable to protect the molten metal both while it is being transferred from the electrode to the work and while the deposited metal is solidiiying and cooling; and to provide in the coating the necessary ingredients to accomplish this purpose. To protect during the solidifying and cooling, it is desirable to provide on the molten metal a. thin lm of protective material, and to have this iilm substantially continuous and unbroken until the metal has solidified andcooled; but to have the lm of such character that when the whole is cold such lm is quitefriable and easily removable. By maintaining the film unbroken while the weld-metal is liquid, unevenness of the surface and ofthe boundary of the weld is in large measure avoided. While the same materials which protect the deposited metal also serve to some extent to protect the metal as it is being deposited from the electrode, this latter protection may be more ei'ectively obtained by providing a non-oxidizing gaseous envelope for the metal as it is being deposited; and this gaseous envelope can be obtained by providing in the weld-rod coating an organic material, such as Wood ilour, which burns to yield carboniferous gases, such as carbon dioxide.

I have discovered that I can obtain the desired t results by providing in the weld-rod coating a mixture of ilmenite with a magnesium-bearing silicate, such for instance as talc or asbestus; and binding the mixture together and to the 4o weld-rod core by a silicate binder, such as sodium silicate. also contain other metals, for instance iron. 'I'he ilmenite serves to maintain an unbroken protective lm while the deposited metal is liquid and until it has solidied and cooled. Although either the ilmenite alone or (usually) .the magnesiumbearing silicate alone is not friable, and tends in general to yield a slag 'which is hard to remove,

even with sodium silicatepresent, the co-presence of the ilmenite and the magnesium-bearing silicate makes a resultant slag which is quite friable and easily removable.

In addition to these three fundamental ingredients, I may and desirably do provide other ingredients in the coating. 'I'he chief among these The magnesium-bearing silicate may.

is an organic material, such as wood flour. Others may be ferro-manganese and gum arabic: but they are relatively secondary.

The accompanying drawing shows a coated Welding electrode or weld-rod embodying my in- 5 vention. Fig. l is an elevation of such a coated welding electrode, partly broken away to show a longitudinal section; and Fig. 2 is a cross-section of such coated welding electrode, on the line 2 2 of Fig. l. l0

In such drawing a metallic wire or rod l0, usually a ferrous wire or rod of desired composition, is covered for all or the greater part of its length by a coating li and this coating is made of the mixture of ilmenite and a magnesium- 15 bearing silicate, with a binder silicate (such as sodium silicate) desirably with wood flour, ferromanganese, and gum arabic also present, as described above. 4

'I'he ilmenite, which is an iron titanate, is suitably reduced to a powder, for intimate mixing with the other ingredients used. v

The magnesium-bearing silicate is also reduced to a powder, as by grinding, for intimate mixing with the other ingredients. It is most con- 25 veniently talc; but other magnesium-bearing silicate may be used, such for instance as asbestus, sepiolite, deweylite, serpentine, amphibole, etc.

The binder silicate is desirably either sodium silicate or potassium silicate; desirably in the 0 -form of water glass if sodium silicate is used, o r of the analogous substanceif potassium silicate is used.

These three ingredients may vary widely in, their relative proportions. The ilmenite and the 35 magnesium-bearing silicate may each vary from 10% to 40%, of the whole formed by these three ingredients, with the binder silicate (sodium silicate) forming the residue of that whole. An eiective proportion is with the ilmenite and the talc each forming 25% of that whole, and thel sodium lsilicate (computed after it has lost its water) forming 50% of that whole.

Wood flour, or other powdered organic material, may be added in desirable amount; conven- 45 iently in the proportions of 15% to 50% of the total weight of ilmenite and the silicates.A

Ferro-manganese, in powdered form, is also desirably added in the coating. It has a multiple action. It supplies manganese which may 50 be lost during the Welding operation. It helps in forming the protecting coating. It also has a deoxidizing action, to protect against oxygen which may enter the heated space. It lmay vary in amount, but conveniently forms'between 10% 55 and 40% oi the total weight of ilmenite and the silicates.

Gum arabic is also a desirable ingredient. It has several functions. Among these are that it helps in the binding action, and also helps in furnishing the carbonaceous gases. It usually is present in relatively small amount, such as 2% vto 15% of the total weight of ilmenite andthe silicates.

I give below an example of a coating mixture which I have found very eil'ective, and which em- I Vbodies all of the ingredients discussed above, al-

though not all of them are necessary:

In making the coating mixture, the ingredients are suitably mixed in the desired proportions,

and applied to the electrode-core in any suitable manner, as by being extruded thereon. The rod which has thus been coated is suitably dried, and is used in the usual manner of welding electrodes. It can be effectively used in all positions, not only in the so-called down-hand welding, in which the work is below the electrode, but also for welding on Avertical surfaces and in overhead welding. Also, the electrode is found not only to work with reverse polarity, or when it is connected to the positive side of the circuit, but also to work quite well on straight polarity, 'or when it is connected to the negative side of. the circuit-a versatility of operation which is unusual.

I claim as my invention:

1. A weld-rod having a coating containing ilmenite, talc, and a binder silicate, with each of the lirst two forming from 10% to 40% of thetotalofthethree.

2. A weld-rod having a coating containing ilmenite, talc, and a binder silicate, with each of the ilrst two forming substantially one-fourth of the total ol.' the three.

HARRY R. PENNINGTON.

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