DE1232291B - Core electrode for the arc welding of steel - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

B23k

German class: 21h-30/16

Number: 1232291

File number: U10179 VIII d / 21 h

Filing date: October 3, 1963

Opened on: January 12, 1967

The invention relates to a core electrode for arc welding steel with a Core made of alloy materials and carbon-containing, gas-evolving substances, preferably for the build-up welding of railroad tracks.

Replacing and maintaining worn metal components is often difficult and costly. the Railway companies must constantly maintain the rails or replace them if they are too worn. The wear and tear on the rail joints is particularly high due to the impact of the wheels. The preferred one Repair procedure consists of overlay welding the worn areas of the rail ends with one that is resistant to downforce and compatible with the base material Alloy.

In general, the rod or wire electrodes are welded in an open arc. When welding and steeling outside the workshop, for example for the maintenance of railway track parts on the line, it is desirable to do without inert gas protection. To compensate for the lack of gas protection, known tubular electrode fillers contain an organic powder (wood or other vegetable products) or an inorganic powder, such as siderite (FeCO ₃ ) or limestone (calcium carbonates) gaseous envelope (preferably CO and CO ₂ ) is formed to protect the arc current and the deposited melt.

The use of the above-mentioned organic and inorganic powders has limitations that prevent further exploitation of the open arc process, the more effective and is more economical than other comparable welding processes. These generally result from the The fact that plots made with such known materials in the composition and their physical and mechanical properties often vary considerably.

The main object of the present invention is to provide an improved tubular rod or Wire electrode for welding or surface finishing with an open arc, especially when used railway tracks are to be repaired.

The invention provides a core electrode which is characterized in that the carbon-containing, gas-evolving substance consists of amorphous carbon with a particle size of approximately molecular dimensions, 0.5 to 3% of the core mass of core electrode for arc welding
of steel

Applicant:

Union Carbide Corporation, New York, N.Y.

(V. St. A.)

Representative:

Dipl.-Ing. H. Görtz, patent attorney,

Frankfurt / M., Schneckenhofstr. 27

Named as inventor:

Trunk Phillip Culbertson, Kokomo, Ind.

(V. St. A.)

Claimed priority:

V. St. v. America October 3, 1962 (228 037)

makes and with the alloy materials, which in a known manner have a particle size of less than 0.5 mm, is intimately mixed.

Advantages and possible applications of the new invention emerge from the exemplary embodiments as well as from the following description. It shows

F i g. 1 is a circuit diagram showing the corresponding means for welding rails with the inventive Electrode illustrates

F i g. 2 is an enlarged cross-sectional view of the tubular electrode and FIG

F i g. 3 is a plan view of a rail connection.

As in Fig. 1, a weld circuit is formed by contacting the electrode 10 with the surface of the rail 12 to be repaired, including a DC power source 14, conductor 16, relay coil 18, feed rollers 20, electrode 10, rail 12, and a ground or return line 22 has. This excites the welding arc 24 and at the same time closes the relay contacts 26, which feed the wire feed motor 28 from the generator 30. The generator in turn drives the wire feed rollers 20, which pull the electrode wire 10 off a reel 32. The operator merely moves the guide tube 34 with the aid of the handle 36 to, as in FIG. 3 illustrates applying weld metal 38 to the worn area of the rail end.

609 757/328

As in Fig. As illustrated in FIG. 2, the core electrode 10 is composed of a filler material 42 according to the present invention containing steel shell 40.

Components are used to achieve the desired proportions of the elements in the filler material in the form of powder with particle sizes less than 0.5 mm, as illustrated in Table 1, thoroughly mixed and placed in a thin steel shell. A suitable shell material is simpler, 0.05 to Carbon steel containing 0.15% carbon.

Chromium is present in the iron-based alloy deposit as a carbide former to ensure strength and hardness. Manganese and molybdenum are present in the deposit to provide shock resistance, abrasion resistance, and hardness. Although the chromium, manganese, and molybdenum contents can vary as illustrated in Table 1, the total content in the deposit should not be less than 6%. Silicon impurities are allowed up to 0.5%. Aluminum and titanium can be used as residual elements up to 0.1 or 0.25%
Deposit be present; however, these elements are usually lost during the steeling process. The aluminum-titanium compound in the filler material acts as a deoxidizer and flux. The potassium titanate serves as an additional flux. The carbon contained in the deposited alloy is mainly important as a carbide former to produce hardness, abrasion resistance and strength. The remainder of the deposited alloy consists of iron and the common impurities associated with this group of alloys, ie phosphorus, sulfur and the like. These impurities should be kept very low.

The filled electrodes can be coated with a thin layer of copper to improve the electrical contact and coated to prevent rust, which also acts as a lubricant for the feed mechanism can serve. Preferably the thin one

so steel strips are coated with copper before it is processed into a tubular casing.

Table 1
Preferred composition of the filler material

Amount added
Weight percent

Material Approximate particle size

36.00

3.30

4.50

52.95

1.00

2.00
0.25

High carbon ferrochrome

Carbon 7.00% max

Chromium 66.00 to 69.00%

Silicon 1.00 to 3.00%

Standard ferromanganese (low phosphorus content)

Manganese 78.00 to 80%

Carbon 7.00% max

Silicon 2.00% max

Phosphorus 0.10% max

Ferromolybdenum

Molybdenum 62.00 to 64.00%

Silicon 0.20 to 0.60%

Carbon 0.018 to 0.064%

Copper 0.13 to 0.21%

Sulfur 0.02 to 0.10%

Phosphorus 0.010 to 0.023%

Iron powder (loss in hydrogen 2% max)

Metal iron 97.00% max

Carbon 0.08% max

Manganese 0.20% max

Sulfur 0.025% max

Phosphorus 0.025% max

Silica 0.15% max

Aluminum-titanium (high purity)

Aluminum 45.00 to 46.00%

Titanium 53.00 to 54.00%

Iron 0.50 to 1.00%

Silicon 0.01 to 0.09%

Carbon zero to 0.08%

Lamp soot
Potassium titanate

less than 0.5mm

less than 0.5mm

less than 0.5mm

less than 0.147mm

smaller than 0.146 mm

smaller than 0.043 mm
smaller than 0.074 mm

Table 2 Range of compositions (percent by weight)

far

filling material
I preferred

optimally far

Rail deposition
preferred

optimal

Cr

C (bound)

C (free)

Mn

Mon

Al

Ti

Si

Fe (free)

Fe (bound)

18 to 30
Ibis 5
0.5 to 3
1.5 to 4
0.5 to 4
0.2 to 1.5
0.2 to 1.5
0.2 to 1.5
30 to 60
rest

20 to 25

2 to 4
Ibis 3

3 to 3.25
Ibis 3

0.5 to 1
0.5 to 1.2
0.5 to 1
40 to 60
rest

23 3 2

2.75 2.0 0.7 1.0 0.8

50

Remainder 5 to 7.5
0.6 to 1.2

zero

0.5 to 1.5
0.5 to 1.5
0.2 max
0.2 max
0.5 max

zero

rest

4 to 9
0.5 to 1.5

zero

0.3 to 2.5
0.3 to 2.5
0.2 max
0.25 max
0.5 max

zero

rest

6.5
0.9

zero
1.0
1.0

0.1 max 0.15 max 0.3 max

zero

rest

Best results are obtained when 2 percent by weight amorphous carbon is mixed into the filler powder as free carbon. Free carbon zo in the Füllgemisch stabilizes the arc by an unspecified mechanism. The stabilized arc ensures a uniform melting speed and depth of penetration even with a lower current intensity. (Previously, high currents had to be used to compensate for losses due to unstable arc performance.) The process is therefore less difficult and can be performed by skilled or even unskilled operators. In addition, the consistently good quality of the deposit makes the method useful for servicing railway lines.

Lamp soot is particularly effective as an amorphous carbon additive when it is mixed with the other powdery constituents of the filler material so that its shape approaches a molecular size. The precise mechanism underlying the importance of lamp black in the composition is not fully understood. It is provisionally assumed that the amorphous carbon combines with the oxygen in the air in the _{heat of the arc, as a result of which a CO 2} envelope is formed to protect the deposited bath. Other forms of carbon, namely crystalline forms such as graphite, carbon dust, carbon _{ashes and the like, do not readily form the CO 2} envelope.

Equivalent forms of lamp soot can be the deposition products of the flame resulting from the imperfect combustion of carbonaceous materials or gases, e.g. B. Flame deposits of acetylene, natural or artificial gas, petroleum products and the like. It is believed that the amorphous structure of such soot deposits _{combines more quickly with oxygen to form the CO 2} shell. In addition, the amorphous carbon melts during the steeling process and does not affect the carbon content of the deposited alloy. Experiments show that if only crystalline carbon is used as free carbon in the electrode core in welding processes with an open arc, the carbon behaves irregularly in the bath and results in an alloy with a carbon content that cannot be predetermined. Since the amorphous carbon only creates a low-oxygen atmosphere, crystalline carbon is also added to the filler powder in order to obtain a pre-determinable carbon content in the weld metal.

In addition, it can be assumed that the amorphous carbon is not easily different from the wet molten metal and therefore cannot be absorbed by it as well. The amorphous carbon tries to swim on the bath due to its lower specific weight. A comparison Table 3 shows the properties of the two forms of carbon.

The biggest difference in physical properties between amorphous and crystalline carbon seems to be the thermal conductivity. This is probably due to the extraordinarily porous character of the amorphous carbon. Theoretically, it is believed that amorphous carbon, since it is more porous and therefore a larger Surface, combines more easily with oxygen than the dense crystalline carbon. aside from that the particles of amorphous carbon are naturally very fine compared to crystalline carbon Carbon that has to be mechanically crushed and pulverized.

Table 3 Physical and chemical properties of carbon

characteristic Amorphous carbon Crystalline carbon
or graphite structure amorphous
12.01
1.87
3652 to 3697
4200
8.08
97.85
0.124
unknown hexagonal crystalline
12.01
2.65
3652 to 3697
4200
7.9
94.81
2.48
Yes Molecular weight
specific weight
Sublimation temperature ^{, 0 C}
Boiling point, ⁰ C
Heat of combustion, kcal / g
Heat of Oxidation, cal / g / atom
Thermal conductivity cal / sec, cm ° C
Soluble in liquid iron

Example I.

A mixture of filler material for a tubular steel electrode was prepared according to FIG preferred composition shown in Table 1. After mixing for about 1 hour the material was processed into a rod with a diameter of 2.8 mm. The weight ratio of the simple carbon steel shell to the Fill material was 70:30.

The method of making various sizes of cored electrode, for example 1.5 to 8 mm, while maintaining a certain ratio of casing to filler material known in the art.

The tubular rod was made from those mentioned above Grounds made in the form of a coil with a thin layer of copper. Thin coating process of steel shell material are known in the art. The copper plating is very thin; H. fewer than 0.025 mm, and is likely to be vaporized and / or oxidized in the heat of the arc. The eventual the remaining copper content is only present in traces and does not affect the quality of the deposit.

The cored electrode was open arc onto a disk of ordinary Carbon steel is applied with a welding current of 275 and 30 V (direct current, electrode positive). To get a smooth build-up, the weld beads must overlap each other by about 25%. Three coats were applied; the seeded application was then hardened by cold rolling. Rockwell "C" hardness values for each layer of the hardened plot are shown in Table 4.

Similar compositions were made to test if the cored Can reproduce electrode. These compositions are identified with "Batch No. 7" and "Batch No. 26" designated. Each batch was made into a series of bobbins. Hardness values of deposits aas any coils are shown in Table 4.

Table 4
Composition and hardness of the preselected batch

Batch No. 7

Composition, percent by weight
! Filling powder j

Deposit Batch No. 36

Composition, percent by weight
Filling powder | deposit

Si ..
Mn
Mon
Al.
Ti.

23.66 6.43 4.83 0.79 0.82 0.22 2.84 0.96 3.07 0.90 0.62 0.04 0.94 0.02

21.33
4.55
0.77
2.48
1.44

Hardness Rc

Hardness Rc

6.46
1.03
0.24
0.92
0.96
0.03
0.14

Shift no. area average Hardness] 47.5 Etc area hardness average Rc 1 46 to 49 48.5 46 to 51 48.8 2 38 to 46 42.9 42 to 45 43.4 3 35 to 41 38.5 33 to 41 37.0 Hardened workpiece 3 44 to 50 46 to 50 47.8

Coil no. area average area average 1 53 to 57 55 47 to 49 48 2 51 to 54 52.5 56 to 60 58.8 3 52 to 55 53.0 57 to 60 58.6 4th 51 to 55 53.0 57 to 60 58.2 5 59 to 61 60.0 51 to 54 52.5 6th 57 to 59 58.0 50 to 53 51.5 7th 59 to 63 61.5 55 to 57 56.0 8th 51 to 54 53.0 50 to 53 51.5 9 54 to 55 54.5 50 to 53 51.5 10 57 to 60 58.5 55 to 57 56.0 11 59 to 60 59.5 54 to 56 55.0 Total area average Total area average 51 to 63 56.2 47 to 60 54.3

Example II

Although the hardness of a deposit is a good guide to abrasion properties, it is ideal Evaluation of rail properties only with the actual monitoring of the route via a possible for a longer period of time. Since such testing would be impractical (and dangerous in itself), the American Association of Railroads (AAR) developed a device to test the rolling load. At a The test program carried out by the AAR staff was the one-core weld metal provided electrode according to the present invention (as described in Table 1) as well as three typical commercially available welding electrodes were subjected to the above-mentioned rolling load test. All surfacing were indiscriminately worn on by AAR staff in accordance with standard railroad practices Rails made. The data obtained from these tests are shown in Table 5. These data show that the weld metal of the cored electrode according to the invention, namely alloy A, the weld metal of the

10

knew electrodes was superior. The tests are usually finished after 5,000,000 runs, what is considered the maximum service life, or if excessive or abnormal wear is noted will. It is of particular importance that the degree of wear of Alloy A is considerably lower than that of the other alloys.

The favorable results of the rolling load tests on alloy A allow accelerated testing. Various kilometers of track on an eastern railway line were used as test areas where Alloy A was applied to worn rail ends in an open arc. The welds are continuously monitored and used to determine the abrasion and durability properties evaluated under the actual operating conditions.

The test results for the cored electrode in this example indicate that the tubular Rod according to the present invention for steeling the rail joints to a high degree is suitable in terms of reliability and reproducibility.

Table 5 AAR rolling load test results

Legie Brinell hardness (BI
Test ο t_. 262 IN) of the deposit
before after test By
guided Weld metal abrasion mm Approximate wear
⁶ runs per IO mm tion No. 277 test 627 to 653 runs Vi ₀₀₀ inches 0.13 Viooo inches 0.03 A. A-I 245 600 653 to 665 5,000,000 5 0.65 1 0.13 A-2 255 555 to 600 653 5,000,000 25th 0.39 5 0.10 A-3 262 578 to 600 622 to 633 4,000,000 15th 0.26 3.8 0.06 A-4 309 512 to 555 653 5,000,000 10 0.39 2 0.09 A-5 266 600 324 to 354 5,000,000 15th 0.98 3 0.98 B. BI 255 311 to 347 332 to 364 990 700 39 1.23 39 0.61 B-2 273 306 to 329 290 to 298 2,000,000 49 1.13 24.5 1.10 C. C-I 262 248 to 369 286 to 311 1 008 100 45 1.18 44 0.24 C-2 241 273 to 277 286 to 311 5,000,000 47 0.83 9.5 0.33 C-3 241 255 to 297 321 to 323 2 721000 33 1.18 13.0 1.18 C-4 286 269 to 302 321 to 340 1,000,000 47 1.20 47 1.20 C-5 255 to 302 311 to 356 971 800 48 1.35 48 0.69 D. D-I 298 to 307 2,000,000 55 27.5

The examples and uses of the cored electrode according to the present invention constitute a preferred embodiment of the invention for the sake of clarity. The electrodes according to the invention can be used to carry out welds for steeling or to connect other metal parts than railroad parts. Also, the deposit can also by other known methods with electric arc, in which the workpiece in the electric circuit may be used, although the open arc method is preferred.

Claims (7)

Patent claims: 1. Core electrode for arc welding of steel with a core made of alloy materials and from carbon-containing, gas-evolving substances, preferably for build-up welding of railway tracks, characterized in that the carbon-containing, gas-evolving Amorphous carbon substance with a particle size close to molecular Dimensions, makes up 0.5 to 3% of the core mass and with the alloy materials that are in an known to have a particle size of less than 0.5 mm, is intimately mixed. 2. Electrode according to claim 1, characterized in that the free amorphous carbon consists of Lamp soot. 3. Electrode according to claim 1 or 2, characterized in that the filler material consists of (percent by weight) 18 to 30 Cr, 1 to 5 C (bonded), 1.5 to 4 Mn, 0.5 to 4 Mo, 0.2 to 1.5 Al, 0.2 to 1.5 Ti, 0.2 to 1.5 Si, 30 to 60 free iron, 0.5 to 3 free carbon with a remainder bound Made of iron. 4. Electrode according to claim 1 or 2, characterized in that the filler material from 20 to 609 757/328 25 Cr, 2 to 4 C (bonded), 2 to 3.25 Mn, 1 to 3 Mo, 0.5 to 1 Al, 0.5 to 1.2 Ti, 0.5 to 1 Si, 40 to 60 free iron, 1 to 3 amorphous carbon with a remainder of bound iron. 5. Electrode according to claim 1 or 2, characterized in that it consists of 23 Cr, 3 C (bonded), 2.75Mn, 2.0Mo, 0.7 Al, 1.0Ti, 0.8 Si, 50 free Iron, 2 free amorphous carbon with a remainder of bound iron. 6. Electrode according to Claims 1 to 5, in which the sheath is made of ordinary carbon steel, characterized in that the weight ratio of the steel shell to the filler material is 70:30. 7. A method for direct current arc welding with an electrode according to the claims 1 to 6, characterized in that the electrode has positive polarity. Considered publications:
Swiss Patent No. 171 637;
WM C ο η n, The Technical Physics of Light arc welding, Berlin — Göttingen — Heidelberg— Munich, 1959, pp. 270 and 350. 1 sheet of drawings