DE2438008A1 - WELDING ELECTRODE COVERING - Google Patents

Description

The invention relates to a welding electrode from a conductive metallic part and a flux «. Such electrodes can, for example, consist of a core * wire and a sheath or a sheet metal sleeve and a compacted flux core,

The welding of corrosion resistant nickel alloys such as a 28% chromium and 10% iron-containing nickel alloy, as is commonly used for producing corrosion-resistant pipes, requires special electrodes that permit welding in all positions, and even under strong bias _r tore and result in pore-free welded joints. The weld metal must have the same corrosion resistance as the base material and allow a certain amount of iron absorption when used as an alien filler material or when coating alien metals such as steel

The welding behavior of coated electrodes depends to a very large extent on the coating. The invention lies therefore the object of the invention is to create a flux which is suitable as a coating and which produces particularly good welding results guaranteed and particularly suitable for welding nickel alloys with 28% chromium and 10% iron.

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suitable "The solution to this problem" consists in a flux of 10 Ms 26% calcium carbonate, 5 Ms 20% barium carbonate, 10 to 23% titanium dioxide, 0 to 4% aluminum oxide or alumina, 20 to 30% cryolite, 4 to 18% manganese, 1.8 to 7 | 2% niobium and 0 to 10% chromium. The manganese content is preferably at least 10% and the niobium content is at least 2.4%. The flux according to the invention can also contain up to 2% chromium oxide and up to 7.2% molybdenum as further active ingredients. The mixture of the above-mentioned ingredients can be mixed with additives to ease the pressure, for example bentonite and a binding agent, for example sodium silicate, are added to apply the flux to a core wire as a cladding to be able to.

Is essential that the flux contains all active ingredients in the specified content limits to ensure that cracking in welding and pore-free welds with excellent technological properties result _o In view of a universally, in particular when overhead welding usable electrode, the flux should Contains 24 to 26% cryolite. The flux advantageously contains equal amounts of calcium carbonate, barium carbonate and titanium dioxide «,

The percentages in the following statements relate refer to the total content of active ingredients,

If the calcium carbonate content is below 10%, an unstable arc can result, so that the Slag adheres very tightly and is very difficult to remove. Removing the Welding slag also when the content of calcium carbonate

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is above 26% and therefore has a high melting point results so that part of the flux in solid Condition at the tip of the electrode is a kind of fingernail forms, which affects the arc stability and in particular, vertical and overhead welding is impaired. The flux therefore preferably contains 12 to 20%, for example 15% calcium carbonate. .

In addition, the flux must be 5 to 20% barium carbonate If the barium carbonate content is less than 5%, the result is a liquid one that tends to drip Slag when welding other than normal position. Kept over 20% increase the melting point and lead ^ to the fingernail * formation with the consequence of an unstable arc. Before-' preferably the barium carbonate content is therefore up to 20%, for example 15% «

The flux contains titanium dioxide or rutile mainly to stabilize the arc and to reduce the melting point. As a result, if the content is below 10%, the melting point is too high, so that slag beads are formed. Even with a 23% titanium dioxide on a too high melting point as well as a tough and difficult to remove slag _o The content of titanium dioxide results therefore is preferably 12 to 20%, for example 15%.

The aluminum oxide makes it easier to remove the slag, however, it is not always required. Preferably is the aluminum oxide content is 1 to 2%. With a salary the melting point increases above 4% and there is a risk of fingernail formation «,

The cryolite serves as a refining agent, and reduces

the melting point; its proportion is preferably 24 up to 26%. Outside these limits, the melting point increases, so that there is a risk of melting out of the core wire consists of the sheathing and the arc is impaired, possibly even extinguished will. When used for flat or horizontal welding however, the flux can also be 20% or 30% Contain cryolite, since in this case it is possible to weld with higher amperages without any difficulties with regard to the welding as for vertical or overhead welding

The flux must contain 4 to 18% manganese and 1.8 to 7.2% niobium, in addition to the other components, in order to ensure a melting point that prevents fingernail or pearl formation. In addition, the higher the manganese and niobium contents, the lower the risk of cracking. Accordingly, when welding a nickel-chromium-iron alloy with 28% chromium and 10% iron, the remainder nickel preferably contains 13 to 16% manganese and 4.8 to 6% niobium. On the other hand, when welding austenitic or ferritic steels and nickel alloys, the flux preferably contains 4 to 8% manganese and 1.8 to 6% niobium is preferably added as ferroniobium with a niobium content of 50 to 70% or as nickel-niobium and niobium powder. On the other hand, manganese and niobium can of course also be introduced into the weld metal from the core wire in order to reduce its susceptibility to cracking.

The flux preferably also contains chromium, since chromium contents up to 10% reduce the porosity, especially when re-

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ignition of the arc is reduced «, In addition, that can Chromium in the flux to replace the chromium content in the core wire.

The flux can contain up to 2% chromium oxide without impairing welding. low manganese contents of, for example, 4 to 8% , a chromium oxide content of 1% improves the arc stability. Chromium oxide contents above 2% , for example 4%, increase the penetration effect of coated electrodes too much and lead to burn-through rather than welding.

Finally, the flux can contain up to 7.2% molybdenum included to reduce the risk of cracking; especially with relatively low manganese contents.

The flux according to the invention can be applied to a core wire in the usual way, for example by extrusion with subsequent drying or firing. The flux is usually made from a finely divided powder with a particle size of less than 80 to 100 mesh in a dry mixture with bentonite. A solution of sodium silicate in water is then added to the mixture with continued mixing until a homogeneous mixture can be applied to a core wire Extrusion results in «. Typically, the mixture contains 3% bentonite and 15% sodium silicate, based on the dry flux _β After two hours' calcination at 370 ⁰ C is formed on the core wire a firmly adhering coating. The possible uses of the electrode depend on its dimensions. In overhead welding, for example, a short circuit can occur if the sheath is too thin. Examples of typical electrode dimensions and preferred

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The current intensities are shown in Table I below. However, these values are by no means binding; for example, the amperage during overhead welding can be reduced when the slag is too fluid.

Table I. Amperage
(A) Wire diameter
(mm) Electrode diameter
(mm) 40-65 2.4 3.7-6.95 65-95 3.2 5.1-5.25 95-125 4.0 5.95 - 6.25

Electrodes with a coating according to the invention are not only suitable for welding nickel-chromium-iron alloys, but also of nickel-chromium and nickel-copper alloys.

The flux according to the invention can be used as a cover or as a filling of a metal sleeve. Of the metallic part of the electrode can be composed very differently and, for example, from a nickel-chromium or nickel-copper alloy with up to 50% chromium, up to 35% or even up to 70% iron, up to 90% Copper, up to 5% titanium, up to 15% manganese, up to 0.5% or also up to 1% carbon, up to 3% silicon, up to 10% molybdenum, up to 5% aluminum, up to 1% tantalum and up to 6% niobium, the remainder including impurities caused by melting Nickel.

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However, the flux according to the invention is particularly suitable for electrodes whose core wire or metallic component is made of a nickel-chromium-iron alloy with 14 to 32% chromium, 0 to 0.1% carbon, 0 to 2.5% manganese, 0 to 2.5% silicon, 0 to 5% titanium, 0 to 5% aluminum, up to 25% iron, 0 to 1% tantalum and 0 to 2% niobium, the remainder including _{impurities caused by the smelting nickel consists of 0} The impurities include deoxidation and refining residues and other impurities commonly found in nickel-chromium-iron alloys.

For welding nickel alloys with 28% chromium and 10% iron are particularly suitable core wires made of 0 to 0.1% carbon, 0 to 2% manganese, .0 to 2.5% silicon, 24 to 32% chromium, 0 to 5% titanium, 0 to 5% aluminum and 0 to 25% iron, the remainder 50 to 67% nickel, preferably with a maximum of 0.05% carbon, up to 1% manganese, up to 1% silicon, 27 to 31% chromium, up to 1% titanium, up to 1% aluminum and 8 to 12% iron, the rest 52 to 65% nickel together, with coatings of 12 to 20% calcium carbonate, 12 to 20% Barium carbonate, 12 to 20% titanium dioxide, 1 to 2% aluminum oxide, 24 to 26% cryolite, 13 to 16% manganese, 4.8 up to 6% niobium and 0 to 6% chromium and preferably from 15% calcium carbonate, 15% barium carbonate, 15% titanium dioxide, 1% aluminum oxide, 24 to 26% cryolite, 13 to 16% manganese, 4.8 to 6% niobium and 0 to 6% chromium, the remainder iron from the addition of ferro-alloys. » Also contain the wrappers 3% bentonite as a pressing agent and 15% sodium silicate as a binding agent.,

The weld deposit composition naturally depends on the The type of core wire, its sheathing and the

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settlement of the base material at). When welding an alloy With 28% chromium and 10% iron, the remainder nickel with the electrodes mentioned above, "the weld metal consists of 50 to 67% nickel, up to 25% iron, 24 to 32% chromium, 1 up to 8% manganese, up to 0.7% titanium, 0.5 to 3% niobium, up to 0.8% silicon, up to 0.1% carbon, up to 1.1% aluminum, and up to 0.1% magnesium or preferably from 52 to 65% Nickel, 8 to 12% iron, 27 to 31% chromium, 3 to 5% manganese, up to 0.2% titanium, 1 to 2% niobium, 0.2 to 0.6% silicon, up to 0.05% carbon, up to 0.1% aluminum and up to 0.02% magnesium.

The core wire is used for welding austenitic or ferritic steels or alloys with a high nickel content preferably from 0 to 0.1% carbon, 0 to 2.5% manganese, 0 to 2.5% silicon, 14 to 18% chromium, 0 to 5% Titanium, 0 to 5% aluminum, 0 to 25% iron, 0 to 2% niobium, 0 to 1% tantalum and over 1.5% niobium + tantalum or preferably Made of a maximum of 0.05% carbon, a maximum of 1% manganese, a maximum of 1% silicon, 15 to 17% chromium, up to 1% Titanium, up to 1% aluminum, 6 to 8% iron, up to 1.5% niobium, up to 0.5% tantalum and over 1.5% niobium + tantalum. For such Electrodes, a flux of 12 to 20%, preferably 17% calcium carbonate, 12 to 20%, is suitable, preferably 16% barium carbonate, 12 to 20%, preferably 16% titanium dioxide, 1 to 2%, preferably 1% aluminum oxide, 24 to 26%, preferably 25% cryolite, 4 to 8%, preferably 7% manganese, 1.8 to 6%, preferably 5.4% niobium, 1 to 2%, preferably 1% chromium oxide, 1.8 to 6%, preferably 3% molybdenum and 1 to 6%, preferably 3% chromium, the remainder iron from added ferroalloys as well additionally 3% bentonite and 15% sodium carbonate,

The nickel-chromium-iron electrodes described result

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a healthy weld metal with mechanical properties and a corrosion resistance that corresponds to the base material made of a nickel alloy with 28% chromium and 10% iron. In order to achieve optimal corrosion resistance, the carbon content of the weld metal should be kept below 0.05%, preferably below about 0.03%, and the chromium content should be at least 26% or 27%, preferably about 28%. A low susceptibility to cracks is guaranteed if the weld metal contains at least 0.5%, preferably about V / o niobium and at least 1%, preferably about 3% manganese.

In numerous comparative experiments, the superiority of those provided with a coating according to the invention has proven itself Electrodes Shown In these experiments, the flux was as shown in Table II below resulting compositions, of which envelopes 1 to 18 fall under the invention, while the envelopes A to G are outside the invention. All of the fluxes contained 3% bentonite and 15% sodium silicate as a 47% Baume solution, based on the dry weight, and were on a 3.2mm core wire made of .0.02% carbon, 0.16% manganese, below 0.02% sulfur, 29.8% Chromium, 0.29% aluminum, 0.14% titanium, 0.14% magnesium and 0.014% iron, the remainder nickel applied by extrusion. All electrodes were on for two hours Fired at 288 ° C. . .

The electrodes were designed for overhead welding with direct current Reverse polarity and an amperage of 85 A used when welding were carried out in a single pass 60 V-joints with a root width of .9.5 mm in 12.7 mm thick sheets of the same composition as the Core wire filled in this way should be a second

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Passage of a 60 ° V-joint can be simulated, which is known to be extremely difficult when welding with multiple Passes applies. The tests proved the excellent suitability of the electrode according to the invention, of which the one with the casing 11 showed an optimal behavior. The arc stability was long by both as well as with a short arc excellently with no tendency to short circuit or fingernail formation. The welding slag could be removed with a hammer and chisel without leaving any residue, so that no Pretreatment, for example grinding, was required »The weld seam was completely uniform with excellent Transition to the side walls of the joint and had a flat, only slightly convex contour in cross section. In contrast, the results of the welding tests with the electrodes of the covers A to G were all inadequate. In particular, sheaths A, C and F showed a strong tendency towards fingernail formation, while when welding the electrode to the casing C, there is a weld seam with a strong raised edge from which the slag was difficult to remove.

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Table II

Umhta- external CaCO, BaCO, TiO ₉ , AiUO, Na, Al Mn FeNb Cr lung diameter- ° ° * - * F ₆ ⁰ knife

(mm) (o / o) (Ji) (Ji) (Jt) ■ "- (- Jij '(Ji)' (Ji) (Ji)" (Ji)

1 4th .8th 16 14th 17th 3 25th 15th 10 0 2 4th .8th 16 14th 17th 0 25th 15th 10 3 5 c1 16 14th 17th 1 25th 15th 10 4th -P- VJl = 1 16 14th 17th .1 25th ■ 15 10 4th VJl 5, .1 16 14th 17th 0 25th 15th 10 4th 6th 5, .1 16 14th 17th 3 25th 15th 10 4th 7th 5, , 3 16 14th 17th 1 25th 15th 10 4th 8th VJl , 3 16 14th 17th 3 25th 15th 10 '4 - 9 VJl , 3 12th 16 17th 1 25th 15th 10, 4 - 10 5. »3 21 8th 16 1 25th 15th 10 4th 11 5. .3 15th 15th 15th 1 25th 15th 10 4th 12th VJl , 3 18th 13th 14th V 25th 15th 10 4th 13th VJl , 3 12th 14th 19th 1 25th 15th 10 4th 14th 5. 3 18th 10 17th 1 25th 15th 10 4th 15th VJl
a 3 16 16 16 1 25th 12th 10 4th 16 5. 3 14th 14th 13th 1 25th 15th 10 8th 17th 5. 3 14th 17th 13th 1 - 25th 15th 10 VJl 18th 5. 3 15th 15th 14th 1 25th 15th 10 4 ICr ₀ O, A. 5. 3 16 14th 17th 1 . 25th 20th 10 4th B. '5 = 3 12th 12th 1H 1 25th 15th 10 4 10Ni C. 5. 3 16 16 1 • 23 15th 10 4th D. 5o 3 13th 14th 13th 1 25th 15th 10 5 4ZrO ₂ E. 5. 3 14th 14th , 13 1 25th 15th 10 5 '4Cr, 0, F. 5. 3 13th 12th 12th 1 25th 15th 10 12th G 5. 3 12th 12th 15th 1 '25 15th 15th .4 -

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Further experiments were carried out with electrodes, some of which were encased according to Table I, but others Core wires possessed to have the strength and corrosion resistance, to investigate. The compositions of the core wires and base materials result from the following Table III, while the data for the electrodes are shown in Table IV. The alloy residue With the exception of steel 4, it was always made of iron. All of the alloys in Table III, with the exception of of soft steel 4 to the group of nickel alloys with 28% chromium and 10% iron. From Table V are the Welding conditions and results can be seen, while Table VI shows the compositions of the welds except the balance of nickel and Table VII their room temperature room temperature properties including those of an Alloy 2 listed last position reproduces. When welding in the normal position, a single U-joint was also used a bevel of 15 °, a radius of 6.4 mm, a web flank of 2.4 mm and a root gap of 3.2 mm filled. With build-up welding in normal position 10 adjacent weld beads were applied. When overhead welding, a 60 ° V butt weld was made in a 25 »4 mm thick plate, the first Pass in the normal position and the following passes in the overhead position were made. The pipe welding took place out of position on a pipe with an inside diameter of 66.7 mm and an outside diameter of 79.4 mm and a joint with an incline of 45 ° and a land area of 1.6 mm. The first pass was using of alloy 5 executed as filler material according to the TIG process.

The welded joints were examined radiographically. In addition, 6 or 7 transverse samples were made in each case and polished, etched with Lepito etchant and at

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ten times magnification microscopically, examined. In the bending tests on which Table V is based, two transverse specimens, now 9.5 mm thick, of each weld joint were bent through 180 ° using a bending mandrel with a diameter of 38 mm. In each case, one test was carried out in the as-welded state and a further test after a twenty-hour glow at 904 ^° C. and cooling in air. The number of cracks each. Cross-section according to Table V represents an average value of the pairs of specimens.

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Table III

Alloy C Mn Si Cr Al Ti Mg Fe Q N

(Ji) (Ji) (Ji) (Ji) (Ji) (Ji) (Ji? (Ji) (Ji)

OO CO

0.067 0.25 0.21 28.9 0.08 0.31 0.02 10.9

-0.021 0 _o 16 0.02 29.8 0.29 0.14 0.014 8.6 0.0039 0 ₀ 0635

0.005 0.07 0.06 28 _O 8 0.17 0 _o 24 0.020 10.4 0.0063 0 _o 0017
cn

ο 4 0.18 0o41 0.10 - 0 _o 060 - - remainder

CD

5 0.051 0c16 0.19 28.3 0.84 0.48 0.023 10.2 0.0034 0.0023

° ι

6 0.019 0.29 0.29 29.0 0.036 0.11 0.058 10.3 0.0180 0.0280

Table IV

Electrode core wire coating wire diameter electrode diameter ' diameter

(mm) (mm)

1 1 1 ■ 4.0 5.6 2 1 2 4.0 5.6 3 2 4th 4.0 6.1 4th 2 4th 3c2 "5.1." ■. 5 2 4th 2.4 3.8 6th 2 5 4oO 6o1 7th 2 6th 4.0 6.1 8th 2 11 4 _β 0 -6.1 9 2 15th 4.0 6.1 10 3 17th 4.0 6.1 L. 2 • ^A 4oO . 6.1 M. 2 G 4.0. dreary

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Table V

Electrically welded position such trοde

Welding root through defect polished seam work- ing thick fabric

(mm)

Cracks / cross-section bending test

Annealed as welded

1 err 1 Normal position 25.4 2 20th mm * Oc 09 0 2.0 loo ο 4 U-joint 0.08 2 co 2 H 25.4 2 20th - O ₀ 30 .1.9 1.0 1.0 3 OO
CD 3 Il 25.4 2 30th - 0.38 0 0 3A OO 5 3 Normal position 12.7 4th 10 _ 0 _ 0 S 6 assignment OO 4th Over head 12.7 2 9 3 pores 0.8 0 0 0 -3
1-7 mm dia.in 8th 15.2 mm 9 5 pipe 6.4 5 6th 3 pores 1.6 0 0 0 10 6th Normal bearing 25.4 6/4 21 mm dia. 0.15 0 1.5 S. U-joint T 7th H .25.4 6th 21 - 0.30 0 _o 5 0.5 8th » 25.4 2 21 - 0.2 0 0 9 ti 25.4 2 16 - 0.3 0 0 10 Ti 25.4 2 21 - 0 1 _o 0 L. II 25.4 6th 21 - 0 0 M. Il 25.4 2 20th - -

OO G Q Op

• SR

Ä OS , 068 IN
VO
O , 082 , 082 .075 ZZO ' .081 , 075 , 037 LN
O .082 O O O O O O O O O O ο O 9 ^ OZO ' T "
LN
O , 081 OJ
LN
O , 084 , 079 .079 .079 , 084 , 082 IN
O O O O O O O O O O O O ζϊ »SP vo
LA O
CM O
IN O
O O
VO S. 00 LA C ^ O
vo τ- τ- τ- CM τ- τ- τ- τ- ro co «^ -N.
(XJ ^. 13.6 10.9 8.8 CM ro
O
sr- T-
O *> Τ
α
σ \ 3 * 6 10.6 Τ
Ο
σ \ IA
* ro
O
O
•
O 0.008 0.006 0.006 .008 , 008 τ-
Ο , 013 .006 800 * .006 • Η '"^
EH ^. 0.120 0.083 0.120 0.062 O O O ρ O ο ο Si g 0.04 0.03 0.08 0.04 0.060 ■ 8
O
O
O 0.062 VO
IN
O
•
O 0.080 0.100 0.150 o m co
a
VO
co 28.0 27.3 28.2 0.03 0.04 0.026 0.14 0.050 0.05 0.084 CQ 9 LA
ro ro
ro CM C--
CM CM
(N
CM IN
CO LA
O
IN
CM vo
(N
CM 27.3 26.8 27.7 ro
ro ro ro
ro τ-
ro (N
ro ro • 5-

LA

ro

ro

ro

oo co LA 00 0 ro -et IA

CM (M VO

vo ία ro f

QOOO

CM 00

[νια σ \ (s · ο is ·

ro ro ro cm <f ro

ο ο ο ο ο ο

O O, O O O O

CM

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Stretch limit
(N / mm) Table VII strain
) 25.4mm Snug ¹ 460 28.5 45.5 attempt 387 Zugf.
(N / mm ² 35.5 43.2 Breaking point 1 455 710 22.0 40.2 Weld metal 4th 452 710 25.0 36.0 Il 8th 420 686 26.0 36.8 Il 9 ■ 358 701 39.5 69.8 It 10 372 653 42.0 60.0 It S. 657 Basic work
material 2 730 -

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The data in Table V clearly show that the electrodes with the coating according to the invention produce a healthy weld metal. Welding tests 4 and 5 showed this except normal position only. minimal porosity. the • Properties of the weld metal of tests 3A and 6-show, that the electrode results in a weld metal that is insensitive to iron absorption. As a result, the Electrode for build-up welding of an alloy with a higher Corrosion resistance and to create unrelated connections, as they are often used in tank construction or occur in other weldments that require a beam. Although the one with the electrode L produced weld metal S was healthy, was the behavior this electrode lying outside the invention

unsatisfactory since it formed fingernails and resulted in a weld deposit with raised edges. That also with an electrode lying outside the invention The produced weld metal T was found to be healthy in the X-ray examination; it turned out however, difficulties in removing the slag, because the weld metal did not have flat but raised edges.

To investigate the corrosion resistance, were Transverse samples of weld metal 1, 2, 7 and 10, including the base material, every forty-eight hours immersed in boiling 65% nitric acid. The respective , Weight losses with different test duration are shown in Table 'VIII and are, for better assessment of a weight loss of 20 Ms 30 mg / dm / day of a 28% chromium and 10% iron containing Compared to wrought nickel alloy.

The somewhat stronger corrosion of the weld metal in the experiments 1 and 2 is due to the relevant levels of carbon

.50 980 87 0979

and chrome conditionally. The electrode of welding test 1 had a core wire with a carbon content of 0.067% and a chromium content of 28.9%, while the coating contained no chromium. The resulting The carbon content of 0.062% and the chromium content of 26.2% of the weld metal caused an undesirably high level Corrosion.

The weld deposit of Experiment 2 was made using an electrode of the same composition as that of the experiment 1, but the clad contained 3% chromium. The weld deposit in question contained 0.052% carbon and 28% chromium; it was subject to noticeably less corrosion than the weld metal of test 1. The difference, the carbon content of the weld metal in experiments 1 and 2 can be traced back to segregation in the core wire. The use of core wires with a little lower carbon content of 0.021% and 0.005% in the frame Tests 7 and 10 resulted in significantly lower carbon contents in the weld metal and a corresponding one better corrosion resistance than the weld metal from tests 1 and 2. The corrosion resistance lasts Compared to the corrosion resistance of the kneaded base material. In none of the attempts a preferred attack in the weld metal or in the heat-affected zone could be determined.

More Huey tests on annealed samples showed that a four-hour Sensibilisieren.bei not impaired 593 ⁰ C with air cooling and a twenty-hour sensitization at 704 ° C with air cooling, the corrosion resistance.

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Table VIII

attempt ( C. Cr 2 Nb Corrosion rate 96 144 192 240. 0, %) (%) 0 (4) (mg / dm ² / day) H H H - H 0, 062 26, 4th 1.56 48 179 392 1018 619 0, 052 28, 3 1.2. H 63 1 0, 037 27 1.8 66 18th 20th 2 027 27 1.9 24 1.2 , 12 7th 18th 10 19th

The following experiments illustrate the effect of the Niobs in the flux. Five electrodes 11 to 14 with different niobium contents in the envelope used. In either case, a core wire came with one 4 mm diameter with an electrode diameter of 6.1 mm for use. The core wire consisted of 0.021% Carbon, 1.16% manganese, 8.6% iron, 0.02% silicon, 29.8% chromium, 0.29% aluminum, 0.14% titanium and 0.014% Magnesium, the rest nickel.

The cladding consisted of a flux with 15% calcium carbonate, 25% cryolite, 1% alumina, 15% manganese, 4% chromium, and 15% each of barium carbonate and titanium dioxide in the case of the electrodes 11 to 13 and 14% each of barium carbonate and titanium oxide in the case of Electrode 14 and in all cases 3 / o bentonite and 15% sodium silicate in addition to nickel and ferroniobium with 60% niobium in the amounts shown in Table IX.

The electrodes were butt welded 25.4 mm

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thick plates made of a nickel alloy with 0.031% carbon, 0.14% manganese, 9.6% iron, 0.06% silicon,
30.8% chromium, 0.15% aluminum, 0.16% titanium and 0.018%
Magnesium, the remainder nickel used. The welding was carried out in the normal position with a 15 ° U inclined joint with a web flank of 2.4 mm, a radius of 6.3 mm and a
3.2 mm root gap. The fugue was in eighteen
Passages filled, with the welding slag
Easily removed with a hammer and chisel between each pass. The test data listed in Table X clearly show the advantageous effect of the niobium in the cladding on susceptibility to cracking.

Table IX electrode Ni 11 10 12th 6th 13th IV) 14th 0

FeNb

Try electrode

11 11 12th 12th 13th 13th

Table X Sweat
State Bending ver
search
20 h
704 ° C / air 2.5
0 3.5
0 ler cracks / cross section polished 6.5
Q, 29
0.07

14 14 - 0 0.5 2.0

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As part of a further experiment, an electrode made of a sheathing according to the invention and another core wire with O ₅ 03% carbon, 2.2% manganese, 8% iron, 0.1% silicon, 16% chromium, 0.1% aluminum and 3 % Titanium, the remainder nickel used. The core wire had a diameter of 4 mm with an electrode diameter of 6.1 mm and a coating of 17% calcium carbonate, 16% barium carbonate, 16% titanium dioxide, 25% cryolite, 1% aluminum oxide, 15% manganese and 10% ferroniobium with 60 % Niobium based on dry weight. The coating was made by mixing the flux ingredients with 3% bentonite and 15% sodium silicate. The covered electrode was used for butt welding a 30.2 mm thick plate of the InconeL · - 600 alloy containing 0.04% carbon, 0.20% manganese, 7.2% iron, 0.20% silicon and 15.8% chromium The rest of the nickel was used . The welding was carried out in the normal position and a beveled 15 ° U-joint with a web flank of 2.4 mm, a radius of 6.4 mm and a root gap of 3.2 mm. The joint was filled to a thickness of 30.2 mm over the course of twenty passes, with the welding slag being easily removed between the individual passes using a hammer and chisel. The X-ray examination showed the weld metal to be healthy; Transverse specimens were completely free of defects, even in the bending test even after hardening. .

In another attempt, a 3.2 mm thick core wire was used the aforementioned composition with a 1.9 mm thick coating made of 16% calcium carbonate, 1'4% barium carbonate, 17% titanium dioxide, 25% cryolite, 1% aluminum oxide, 15% manganese and 10% ferro-niobium with 60% niobium. the The electrode in question was used for overhead butt welding a 12.7 mm thick plate of Inconel 600 with nine Passages used. The 'plate had a beveled 60 ° V-joint with a root gap of 3.2 mm and a

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Web flank of 2.4 mm. During the X-ray examination only two pores with a diameter of less than 0.8 mm over a length of 15.4 cm were found. Cross samples proved after a bending test, both in the welded and in the hardened state, are completely free of cracks.

The absorption capacity of the weld metal for iron was investigated in a further test using the aforementioned core wire with a diameter of 4 mm, which was also provided with a sheath of the aforementioned type, albeit 2.1 mm thick. In the experiment, ten beads were welded onto a 12.7 mm thick sheet of soft steel with 0.2% carbon and 0.4% manganese, the remainder being iron. The radiographic examination showed no errors. Transverse specimens were also completely free of cracks after bending around a mandrel with a diameter of 25.4 mm.

The excellent welding properties of electrodes with a molybdenum-containing coating with a lower manganese content than the cover according to Table II were found in further welding tests. The electrodes passed of a 3> 2 mm thick core wire of the composition of tests 7 and 8 from Table VII and a sheath in accordance with Table XI; they were 3.2 mm in diameter. The welding tests were carried out with the electrode combinations the following Table XIII using the coverings according to Table II on a 12.7 mm thick Plate made of alloy 14 carried out.

The electrodes could be used for welding in the normal and vertical position as well as for overhead welding and, when compared with commercially available welding electrodes, resulted in a much more stable arc, better flowability with slag, and a better transition

509808/0879

- 24380

much better weld metal appearance and a lighter one removable slag. During the radiographic examination of the overhead welded connections showed practically no pores, while conventional pores Welding with over 2 pores per mm in one, single Weld bead.

The suitability of electrodes 11 to 13 for welding similar or dissimilar alloys), plates of alloys 9 to 15 according to Table XII used. The process conditions and results are summarized in Tables XIV and XV below. represents. The normal position was welded in in the manner explained in connection with Table V, while overhead welding a 9> 6 mm thick 60 V-butt weld was laid, the first through which walk in normal position. A total of eight passes were required to fill the butt weld, each of which was intentionally interrupted and continued with a new electrode. ' At the job Two weld beads were welded onto one plate made of soft steel or alloy 15. the X-ray examination and the bending tests. were described in the above in connection with Table V. Way done. -

509808/0879

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Table XIII

Electrode core wire cladding

15th
16
17th

7th
7th

Table XIV

Elec- Welding layer welding sheet metal sheet flaw polished
search well 1 2

(mm)

Cracks / cross-section bending test

Sweat residue 20h / 704 ° C / air

CO 15th 15th Normal position "; '25 .4 9 10 ■ - · ■ O O 4mm) O OD
O 16 17th U-joint
Il 25.4 11 11 —- ■ O 2 (Z, O. i (Z.Q. 4mm) 87 O 8 17th 16 Over head 9.6 12th 12th 1Pore
Line 0.9
mm dia O O O 18th 17th Normal position
U-joint 12.7 13th 14th «-» V O O 1 19th 17th Il 12.7 9 9 · O 1 4mm) 1 20th 17th Normal position
assignment 25.4 15th O 3 (Z. Q.

Table XV

attempt Stretch limit
(N / mm ² ) Zugf.
(N / mm ² ) Elongation constriction
(9/25 now)
i%) (#) 71.2
51.2 .Breaking point Notched impact strength at
-196 ⁰ C
Longitudinal
strain
(ü / cm ² ) (mm) - 16
18th 337
310 555
493 27.5
18 _O 5 38.0 Basic work
material
ti - - 1.4 509808; 19th 434 685 14.5 Weld metal Sweat 112
State 1.7 / 087 - 2h / 560 ° C /
Air 128 co

In the bending test 18 small cracks were found in the Melt line with the plate 1, while in the bending test 19 all cracks occurred in the weld metal and in the welded condition led to breakage in the weld metal and in the hardened condition lead to breakage in the melt line.

Instead of the cryolite, it is of course also possible to use equivalent amounts of sodium and aluminum fluoride. Likewise, all statements relating to the core wire and "the sheath also apply to the
metallic sleeve of an electrode with a flux core.

509808/0879

Claims (14)

International Nickel Limited, Thames House, Millbank, London, S.W. 1, Great Britain claims: 1. Welding electrode cover with 10 to 26% calcium carbonate, 5 to 20% barium carbonate, 10 to 23% titanium dioxide, 0 to 4% aluminum oxide, 20 to 30% cryolite, 4 to 18% manganese, 1.8 to 7.2% niobium and 0 to 10% chromium. Z ₀ casing according to claim 1, but containing up to 2% chromium oxide and / or up to 7.2% molybdenum. 3 ο envelope according to claim 1, but at least 10% Contains manganese and at least 2.4% niobium. 4. Enclosure according to one or more of claims 1 to 3, which, however, contains 24 to 26% cryolite. 5. Covering according to claim 1, but each 12 to 20% Calcium carbonate, barium carbonate and titanium dioxide, 1 to 20% aluminum oxide, 24 to 26% cryolite, 13 to 16% manganese, Contains 4.8 to 6% niobium and a maximum of 6% chromium. 6. Wrapping according to claim 5, but the same amounts of Contains calcium carbonate, barium carbonate and titanium dioxide. 7. Enclosure according to claim 2, but each 12 to 20% calcium carbonate, barium carbonate and titanium dioxide, 1 to 2% aluminum oxide, 24 to 26% cryolite, 4 to 8% manganese, 1.8 to 6% niobium, 1 to 2% chromium oxide, 1.8 to 6% molybdenum and contains 1 to 6% chromium. 509808/0879 8. Wrapping according to claim 7, but the same amounts of calcium carbonate, barium carbonate and titanium dioxide. 9α welding electrode with a sheath according to the claims 1 to 8, characterized in that the core wire consists of up to 1% carbon, up to 15% manganese, up to 50% chromium, up to 5% titanium, up to 5% aluminum, up to 70% iron, up to 90% copper, up to 10% molybdenum, up to 6% niobium and up to 1% tantalum, the remainder iron including nickel impurities caused by the smelting consists" . 10. Electrode according to claim 9, characterized in that · '. that the core wire 0 to 0.1% carbon, 0 to 2.5% manganese, 0 to 2.5% silicon, 14 to 32% chromium, 0 to 5% titanium, 0 to 5% aluminum, 0 to 25% iron, 0 to 1% tantalum and 0 to 2% niobium, remainder including impurities caused by the melting process. Nickel contains «, 11. Electrode according to claim 10, characterized that the core wire 0 to 0, carbon, 0 to 2% manganese, 0 to 2.5% silicon, 24 to 32% chromium, 0 to 5% titanium, 0 to 5% aluminum and 0 to. 25% iron, including the remainder, due to the melting process Contains 50 to 67% nickel impurities. 12. Electrode according to claim 11, characterized in that that the core wire 0 to 0.05% carbon, 0 to 1% manganese, Q to 1% silicon, 27 to ~ 31% chromium, 0 to 1% aluminum, 0 to 1% titanium and 8 to 12% iron, the remainder including smelting 509808/0 879 conditional impurities contains 52 to 65% nickel. 13. Electrode according to claim 10 (with a casing according to claim 7), characterized in that that the core wire is 0 to 0.1% carbon, 0 to 2.5% manganese, 0 to 2.5% silicon, 14 to 18% chromium, 0 to 5% titanium, 0 to 5% aluminum, 0 to 25% Iron, 0 to 2% niobium and 0 to 1% tantalum with a total niobium and tantalum content of at least 1.5%, remainder contains nickel, including impurities caused by the melting process. 14. Electrode according to claim 13, characterized that the core wire is 0 to 0.05% carbon, 0 to 1% manganese, 0 to 1% silicon, 15 to 17% chromium, 0 to 1% titanium, 0 to 1% aluminum, 6 to 8% iron, 0 to 1.5% niobium and 0 to 0.5% tantalum with a total niobium and tantalum content of at least 1.5%, the remainder including melting-related Contains nickel impurities. 509808/0879