DE1508346A1 - Covered electrode for welding alloys with a very low carbon content - Google Patents

Description

Dipt.-lng.

BRUNO SCHMETZ, ₅₀₈₃₄₆ Patent attorney η aachin, ** October 1966 Aq * miB «U-U · TiMm 34711

LA SOUDURE ELECTRIQUE AUTOGAlTE ₁ PPROCiJDi) S ARCOS, SA in Brüeael (Belgium)

Description of the patent application

coated electrode for welding alloys is very useful low carbon content

The invention relates to a covered electrode for welding of alloys with a carbon content below 0.03 #, inibee special τοη alloyed steels that have a have such a carbon content, the casing containing a binder and a metal powder mixture, which aua. Alloy metal powders, desoxidizing agents, magnesium oxide, aluminum oxide, whereby these two oxides are present in a combined state, titanium oxide and / or zirconium oxide, the last two oxides being present alone or in combination, as well as fluxes and silicates of several metals.

In the present description, the "basicity coefficient" expresses the ratio (B) , where (B) is the number of Gramn molecules of CaO + MgO + BSO + K ₂ O + Na ₃ O + LiO ₂ + Ca? ₂ and (A) mean the number of Grami molecules of SiO ₂ + TiO ₂ + ZrO ₂ .

Known to run alloyed steels, particularly stainless steels having 18 $ chromium and Q ^c ß> nickel or chromium 18j6, 6 ^ and 3 Lückel $ molybdenum, the more alb 0.05 # contain carbon, risk that they during welding or be subjected to a heat treatment of intergranular corrosion as a result of the precipitation of carbon compounds.

90984WC7S7

The coated electrodes commonly used to weld these alloy steels, known as "low carbon" electrodes and considered to be of good quality, allow, in the majority of cases, a metal with less than 0.06.6 carbon to be deposited. These electrodes are either those with a basicity coefficient of at least 3.0, with their covering containing compounds with an acidic affinity, e.g. titanium oxide and / or zirconium oxide as well as complex silicates of several metals, the proportion of which makes up a maximum of about 15 # of the total powder, in which are included, or electrodes with a Basisitätsbelwert of not more than 0.6, the coating contains a substantially greater amount of these compounds having acidic affinity, and optionally yet _t amphoteric oxides, such as alumina. In the latter type of electrode, the powder mixture added to a binder to form the coating generally contains 1.5-25 alkaline earth carbonates, 35-45 titanium oxide and / or zirconium oxide, 5-15 complex silicate as well as alloying metals, deoxidizing agents and fluxes based on fluorine compounds.

These two types of electrodes apply «in metal, of which Coal off content by 0.015-0.0353t greater than that of the Welding wire · β, which is used as Ι ·· 1 ·. lun contain well · welding wire · generally around 0.015 - 0.03jt Carbon. Egg explains that the carbon content of the applied metal is almost always less than 0.06% but is close to this value. You use welding wires with a relatively low carbon content, e.g. at most about 0.02 ^, and one chooses the height of the covering strictly so that it does not contain too much carbon contained, it is quite easy to apply a weld metal for alloy steels, the carbon content of which is 0.055 » does not exceed. In the majority of all cases, however, this selection of the welding wire and the raw materials used for the sheath yields not a weld metal whose carbon content is below $ 0.03 lies. The likelihood of a weld metal & ll with less Applying as $ 0.02 carbon is even in the case where the welding wire has a very low carbon content, only at 1-2 $ S. It can thus be seen that in reality the same coating corresponds to the applied metal of a larger one

; · 0Ι · 4, / d 7 S 7 ^ ⁰ ORIGINAL

The proportion of carbon transmitted if it is a very carbonaceous soul covered as if it were a soul with some greater throat content. It turns out that the equal coating 0.01-0.025 # carbon in an applied Introduces weld metal, use a 0.025 # welding wire Surrounding carbon content, and that it is 0.015 - 0.035 # carbon introduces into the weld metal if it has a welding wire with 0.015? » Carbon content surrounds.

Although it has already been stated that the electrodes with a Basicity factor of less than 0.6 introduce less carbon than welding wire with a basicity factor above 3.0, with the 4 carbenate content of the former being lower than that of the latter, one cannot expect to be regular • An applied metal has a carbon content of at most 0.02 * Aiurejh TerwenAungron on electrodes, the baseline value of which is "nt" r 0, f.

The submission breath BMin & ung is based on the task, a Electrede su create, which allows to regularly apply a solder metal for alloys and alloy steels, its Carbon not much more than 0.015? * Of the carbon content

Welding wire amounts to. . . ·

The electrode according to the invention is characterized in that in its casing it contains a maximum of 6% carbonates, 3.5-105t deoxidation alloys, at most 1 * organic substances, 3-10% free MgO, 3-10% free Al ₂ O ₉ , whereby the weight ratio MgO to Al ₂ O ₅ "should be between 0.3 and 3.33, and 13 -35Ji of metal powder should be included in the composition of the alloy applied.

A content of aa basic carbonates of at most 6j (of the total weight of those introduced into the composition of the coating Metal powder and a content of organic substances not exceeding 15 times the total weight of the powder have the effect that the Carbon content of the applied Uetalla is reduced. If the basic carbonates and orean substances are completely omitted, the carbon content of the applied

§09844 / 0757 ^BAD

Metals are not more than 0.005 ^ of the carbon content of the braided wire "

The reduction in the proportion of carbonates that have been raised has iiar Effect that the basicity coefficient of the coating is greatly reduced if it is not compensated for by the presence of magnesium oxide in the free state *

The substitution of alkali and alkaline earth carbonates by silicates, Titanates or aluminates "also have the effect of reducing the basicity coefficient too much, for example to less than 0.6 is brought. In addition, some of them harden on contact with water and free alkalis.

In order to ensure correct fusion of the coating, it is also not possible to replace the carbonates by using a mixture of aluminum oxide and silicon dioxide, because silicon is used. dt · applied metal · would be too large. ALtMr content would possibly exceed 0.6 t, as is generally accepted as a permissible value for stainless steels "with 18Ji chromium and 00 steel or for steel with 18ji chromium, B & nickel and 3 * molybdenum" BtI a silicon content above 0.6 ^, For example, if the erritation value does in fact exceed 5? ί.

The use of alkali and earth alkali metal oxides outdoors Condition completely ready · suggested, but only magnesium oxide was suitable because the other oxides too strongly with water react so that a covering and the storage of the K electrodes would appear possible with this covering

In the absence of basic carbonate, a proportion of 1 (# magnesium oxide is used. The proportion of this oxide is the lower, ο if the proportion of basic carbonate is higher, no more is present as 5ji if the mixture does not exceed 6 ° C alkali carbon · * Contains nat.

^ The Yenyendung free magnesium oxide causes the ftaohteil, dal ^ very strong splashes of SohmelzfluO and removing the slag is very erachwert. Avoid using the electrode according to the invention

BATH ORIGINAL

however, these two deficiencies due to their additional peculiarities «

In order to facilitate the removal of the slag, it is necessary that the electrode be subjected to the three subsequent processes at the same time is enough

1. The proportion of the free Magneaiumoxyd to * of the total weight of the powder be between 3 and 10 ff.

2. L *. What part of the free Magr.es iumoxyd should be mixed with a part of the free aluminum oxide, which should also amount to 3-10 $ of the total weight of the powder.

3. The quantitative ratio of free Liagne β iumoxide to free Aluminum oxide should be between 0.03 and 3.33.

The powder mixture can thus, for example, have the same proportion of the two Oxides, e.g. 6? Ί (whereby the ratio of the two oxides to one another is equal to 1 i «t), or 3 # mainesium oxide and 10 # aluminum oxide (at a ratio of 0.3) or 10 # Magneaium and $ 3 Aluminum oxide (at a ratio of 3t33).

Tests have shown that in general the proportion of free magnesium oxide is greater, the lower the proportion of Aluaiiniumöxyd should be and vice versa.

To avoid excessive splashing when welding, measure the Electrode have a quantity of metal powder feeding the alloy 3 which is 13-35 $ of the total weight of the powder mixture of the casing. One can oomit the diameter enlarge the cladding without increasing the amount of slag, and for this reason the melting takes place much more calmly and welding becomes easier to carry out.

Even if the lower limit of $ 13 isn't exactly a critical one Gro2iz3 is so spraying is acceptable in practice, though the mixture has this proportion of metal powders. The upper limit of $ 35 is also not a critical limit. If the

· Ο ·· 44/0757 BADORiGINAL

But if the mixture contains more than $ 35 metal powder, the can Amount of slag that is also coated with the usual given diameter, ground too low. The increase in the diameter of the envelope to which one then becomes in order to obtain a sufficient amount of slag, the handling of the electrode before welding would be too difficult.

In order to reduce the carbon content of the applied metal, the proportion of components other than the Carbonates are reduced, which add carbon in the course of the Sohweißung. From this point of view it is advantageous if no organic substances are added and, in the ! • all that such organic substances are present, if make up no more than 1 # of the total weight of the powders.

The ferro alloys often add carbon to the applied metal. Xe is therefore equally of gate part, the part of ferro-alloys whenever it is possible to replace the deoxidizing ferro-alloys with deoxidizing metal elements which contain them.

The trooken · Powder D εchung, which is in the composition of the Sheathing according to the invention is to be inserted, is as in Combine known electrodes with one or more aqueous Alkalisillkatsn bu, the proportion of which is 15-30? * of their weight should make up.

With the applied metal, carbon proportions of less than 0.03 / S, even less than 0.02 ^, are obtained, depending on whether the Welding wire, which forms the core of the electrode, contains a maximum of us 0.02 ^ or a maximum of 0.01 $ carbon, and if so υ, a serving r / ird whose dry powder mixture they use! * £ ms composed of the following components:

o 5> 5 10 $ o deoxidizing alloys Jj 20 555 * (PiO ₂ and / or ZrO ₂

3 - 10i5 free ifeO BAD ORIGINAL

3 - 1OJ * free A1 ₂ ° 3

4 - 8 # flux, consisting of alkali

or alkaline earth metal fluorides or from cryolite

6 - 12jC complex silicates such as potassium-containing or sodium-containing feldspar, nepheline syenite, asbestos, always, ion, kaolin, pentonite 13 - 35Ji metal powder to form 1 applied alloy.

The mixture is characterized by the absence of Carbonates and organic substances, through a maximum content of titanium oxide and / or zirconium oxide of 35 ^ and a minimum content of these oxides of 20 ° C.

They hang in the metal powder present in the TtahUllMng Special additions to the alloy, especially the alloyed 8takl, 4er should be applied. The alloy elements most frequently used in powder are chromium, ileal, Molybdenum, titanium “ad Hob, these Hemente in almost pure form Per »or s4 # alloy with one another or as a ferroalloy, in the latter case the alloy elements make up 3.3-10j6 of the total weight of the powder.

In Ae-r'Umhüllung a erfindungegenäden electrode for welding reetfreiem steel tob with 18 ^ chromium and t Nickel example is a powder mixture consisting of chromium, nickel and / or Ferroohrom and / or ferro-lflckel and Xlsenpulver, wherein these powders are present in proportions that, taking into account the composition of the welding wire, the weld metal applied corresponds exactly to the composition of the alloy steel parts to be cut.

In order to deposit β in "η steel with about 197 ^ chromium, öf" nickel and 13% iron, an electrode is used, for example, the element of which has a specific gravity of 23, au3 1θ £ chromium, ** S * iii-Jcel and 745 ^ Ilsen and is provided with a cover, the approximate weight of which is 16 and is 30 pounds one

Metal powder mixture of 53 / $ chromium, 5 ^ nickel and 42 <j iron to introduce you to welding.

It is known that when a powder mixture of this type is contained in a casing, the proportions of chromium, nickel and iron which get into the weld metal are approximately 50, 100 and 90%. The melt of this mixture to be supplied to metals thus making in the deposited metal 26; 5 chromium, 5f "nickel and iron from 37 ^, where d * IU per ζ ent number s as a function of the weight of the powder amount of the additive metals are expressed.

The melting of the cladding therefore causes entry into the Welding metal from

16g χ 30 ι 26 »1.248g chrome 100 TOO

16g χ 30 χ 5 * 0.240g Niokel

TTJo

ΊΟ0

: χ I W

16g χ 30 χ 37 * 1.776g iron

Too

1.248g + 3.68g * 4.928g chromium

0.24g + 1.84g = 2.08g nickel

1.77Cü + 17.02g = 18.796c iron BADORIGfMAL

8088U / 0757

It is also known that when the welding wire is melted

there is a loss of about $ 2 chromium. < ^ij

The melting of the welding wire therefore calls the entry into

> .it,

the welding metal from ^:

(18-2) χ 25 m 3.68 g earom

100
8 χ 23 * 1.84g nickel

100
74 χ 23 «17.02g iron ί ^!

The weld metal thus contains:

with a total weight of 251804g weld metal.

The percentage composition of this metal in percent by weight is thus:

4 _f 928 χ 100 ■ 19 | 1 # chrome 25,304

2.08 χ 100 = 8.06 ^ liickel

25.804
18.7 9 6 χ 100 m Tc.QAfj iron

Analog calculations can be used to prove that one Stainless steel with 17.57 * chrome, 10 # nickel, 2.5 # molybdenum and 70 $ iron can be welded by means of an electrode, its sheathing 30 # of a powder mix consisting of 36 # chromium, 18.65 # Nickel, 16? " Molybdenum and 29.35? * Lieen, with the coating for a welding wire that is 18f »chrome, Contains 8 # nickel, 0 # molybdenum and $ 74 iron if that specific Weight of the welding wire 23 and that of the sheath 16 concerns.

As for deoxidizing agents, these can be ferroalloys such as

Pe-Mn, Je-Ti, Pe-Si-Ti and / or among the metals , Al, Ti, Si, Ca

be selected individually or with each other.

A coating composition that produces particularly favorable results when welding a stainless steel of 18 $ ί chromium and 85 »liickel provided, 1st follow'e:

109844/0757

dry powder Parts by weight 6.7 Anti-oxidants
(Manganese and / or Perronangan) 85 29.92 SiO ₂ 380 7.09 ■ free MgO 90 10.24 free ΆΙ2Ο3 130 7.48 OaI ₂ 95 9.05 complex silicate
(Feldspar »Bentonite)
and organic matter 115 29.52 Additional metals in powder form 375

This dry powder mixture was mixed with 290 parts by weight of an aqueous alkali silicate.

A steel welding wire with 18.59 # chromium, 10.7 # liickel, 0.01 ^c / i carbon, 1.28 ^ manganese and 0.24> silicon and a diameter of 3.25 mm was coated with this paste in such a way that that after a drying time of one hour at 375 °, the diameter of the envelope was 5.5 mm.

This electrode was attached to the positive pole of a DC power source connected to a current of 95 amps. during the welding of two horizontal, butted against each other Sheets with bevelled edges or during cutting of a plate standing vertically on a horizontal sheet. The electrode melted off pretty smoothly, and the splash was a little strong. The Schlecke covered the white metal behind the weld pool well, and it could be removed can be done in a simple manner by lightly pecking. The weld bead had the appearance of fine and regular grooves. In the event of the butt welding of horizontal metal sheets it was something concave, while it was very slightly convex when a sheet metal arranged vertically on a horizontal sheet metal was seen. The weight of the metal applied was 115% of the weight of the welding wire. The chemical analysis of this metal showed ι

" ^{/ 07S7} BAD ORIGINAL

Ο _# Ο14? Δ carbon, 1,355? I> njan, 0526 # silicon £ 19.59 chromium, 10.1 fi l.okel.

When "in steel at 18?" Chrome, 85 · Kiok 1 and 3 # molybdenum welded is to be, it is sufficient to pass the above-mentioned welding wire through a sol ohen su replace, which has the same composition as the steel to be welded, and 10? 6 molybdenum powder instead of 10fi iron powder to be introduced into the powder mixture of the casing.

may be the same type of steel with chromium ^'T ickel and molybdenum weld by a Stahlachv / eißdraht nit 18% O. rom and Q & Nickel when molybdenum powder is placed in the Metallpulvermißchur ^ enough so that d & s applied Lie tall used v / ith the desired Composition received.

UIt success have been for example 375 parts of metal powder in the following mixture

iron powder 110 chrome 135 nickel 70 molybdenum 60

used"

BATH ORIGINAL 809844/0757

Claims (13)

r aackin, "^ October 11 -h ■ T" ufon 34731 LA SOUTUHE iLEOTRIQUE AUTOGiUE, PROOfcDÄS ARCOS, S.A. in Brussels (Belgium) claims 1. Covered electrode for welding alloys with a below 0.03? ί carbon content, in particular Steels alloyed with clay, which contain such a carbon content, the coating containing a binding agent and a metal powder odor made from alloy metal powder, sesoxidation agents, magnesium oxide, aluminum oxide, if the oxide is in a carbonized state "Nd / o £ er SirkoniuBoxyd, where the two oil-resistant oxides can be present for calibration or in combination, as well as fluxes and silicates of several metals, d & characterized by the fact that the above-mentioned mixture of a maximum of 6 $ basic carbonates, 3» 5 - 10 '/ * Deoxidizing alloys, not more than V ₁ * organic substances, 3 - 10 # free MgO, 3 - 10 # free H ₂ O, where the weight ratio MgOi A1 ₂ ^ 3 is ^between 3 and 3 »33 and 13 - 35 lbs metal powder, which are to be introduced into the aggregate of the applied alloy. 2. Electrode according to claim 1, characterized by an absence of basic and organic carbonates Fabrics. 3. Electrode according to claim 1, characterized in that the dry powder mixture of its envelope consists of: eOS84A / 07S7 BAD CRIGl; -AL COPY 3.5 - 10O 20th - 35 ^ 3 - 1OfS 3 - 10 '/ » 4th - · 8ϊ'ό De-oxydatioiisle ^ ierun ^ en TiO ₂ and / or ZrO ₀ free IlgO
free Al ₀ O, Flux, consisting of alkali or alkaline earth fluorides or cryolite 6 - * \ 2 ^c , o complex silicates v. ^r ie sodium or potassium alloys "feldspar, llepheline, syenite, asbestos, slimmer, ion, kaolin, betonite and 13 - "55 ^l ß> LIetallpulver r.ls Alloy components of the alloy to be applied. • * 4. Electrode according to one of claims 1 and 3, characterized in that the dry powder mixture, which is introduced into its envelope, of the following composition is equivalent to: Deoxidizer $ 6.7 (Manganese and / or perromanganese) TiO ₂ $ 29.92 free HgO 7 free Al ₃ O ₃ CaP ₅ 7 Complex silicates and organic matter 9 »05 $ Metal powder 29