DE3031149C2 - Powder composition for cored wire electrodes - Google Patents

Description

20-53 20th Rutile concentrate 53.4 Rutile concentrate 10-22.8 Manganese dioxide 4.4 Ferromanganese 1.3-6 Silicon dioxide 3.0 Ferrosilicon 1-5 Sodium oxide 3.0 Sodium hexafluorosilicate 1.3-10 Magnesite 6.0 Burnt magnesite 1.6-7.5 Ferromanganese 13.0 Corundum rest Ferrosilicon 12.0 Iron powder Iron powder remaining (See U.S. Patent No. 38 00 120).

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The invention relates to a powder composition for flux-cored wire electrodes for gas-shielded welding and gas-shielded metal deposition welding of steels.

With the greatest efficiency, this invention can be used in y, cored wire electrodes, which are intended for automatic and semi-automatic welding in all positions.

Some powder compositions for cored wire electrodes are known, which are _{intended for CO 2} welding and CO ₂ build-up welding of steels in all positions, consisting of a steel jacket filled with powdery composition, said composition representing the electrode core. Cored wire electrodes with the following composition (in percent by weight) in particular have better welding technology properties:

Silica manganese 10 to 25 Ferromanganese 1 to 7 Iron powder 2 to 40 Sodium fluoride 0.5 to 3 Potassium silicate 0.5 to 3 Titanium dioxide 30 to 60 Aluminum magnesium 1 to 7 alloy Dimanganese trioxide 3 to 10 Aluminum powder 0.5 to 5.0 (see U.S. Patent No. 38 18 178).

Due to the presence of aluminum and magnesium in the powder composition mentioned, which forms a number of oxides when they are oxidized, it becomes possible when welding with cored wire electrodes with an electrode core made from the powder composition mentioned To obtain welding slag with good physico-chemical properties, which results in good welding When welding with cored wire electrodes, their Core is made from the powder composition mentioned, however, it comes to a high content Oxygen (0.09 percent by weight) and hydrogen (10 to 12 cm 'per 100 g of weld metal) in the weld material, which increases the resistance of the weld metal against hot cracks and also its notched impact strength in the low temperature range is reduced. To the Acceleration of the crystallization of those formed in the course of the melting of the filler wire electrode Welding slag and also to improve the weld seam formation, a significant amount of silicon is introduced into said powder composition. The content of the latter in the weld metal is 0.8 percent by weight, which also has a disadvantageous effect on the plastic properties of the weld metal.

From DE-AS 25 29 200 an electrode wire for steel welding in a carbon dioxide atmosphere is known, which is a jacket made of low-carbon steel, soft with a powdery insert as calcium fluoride, titanium dioxide, ferromanganese, ferrosilicon, Contains iron powder as well as magnesite.

The magnesite reduces the fluid gas excretion.

The object of the invention is to give the flux-cored wire electrodes improved welding-technological properties through the qualitative and quantitative modification of their composition, the content of the Weld seam material to water and oxygen To reduce the minimum and thus to give this high mechanical properties in a wide temperature range.

This object is achieved by a powder composition according to claim 1.

It is particularly preferred that the above components contain in the following ratio are (in% by weight):

Rutile concentrate Ferromanganese

20 to 53 10 to 22.8

Ferrosilicon 1.3 to 6 Sodium hexaflu ». -osilicate 1 to 5 Burnt magnesite 1.3 to 10 Corundum 1.6 to 7.5 Iron powder remaining

Due to the presence of rutile concentrate in the powder composition for FOII wire electrodes according to the invention in the quantities mentioned, a stable arc burning as well as a good in Weld formation guaranteed.

It was found that the lowering of the content of the powder composition according to the invention Rutile concentrate below the lower limit mentioned is less advantageous because it reduces the π Stability of burning the arc is greatly disturbed and a strong splash of electrode metal comes about.

Under the spraying of electrode metal, the spraying of droplets is the case here and in the following To understand welding molten cored wire electrode.

If the upper limit is exceeded, the melting speed of the powder core remains of the filler wire electrode opposite that of its steel jacket back, whereby the content of the weld seam material of non-metal inclusions in the form of non-molten particles of the powder core and thus the properties of the weld metal are significantly impaired. "1

The amount of ferromanganese and ferrosilicon is like this dimensioned so that high mechanical properties of the weld seam material are guaranteed / grounded. Both mentioned amounts of these constituents in the powder composition according to the invention it comes to the r. Formation of easily melting iron manganese silicates in the weld seam material, which easily coagulate and rise to the surface. The non-metallic inclusions left in the weld seam material are round in shape. All of this affects ■ »> the notched impact strength of the weld seam material cheap.

The reduction in the content of ferromanganese and ferrosilicon below the limits mentioned is due to the appearance of pores in the weld seam material r, unfavorable. The introduction of these ingredients in quantities that exceed the upper limit, leads to a substantial increase in the strength and to a reduction in the ductility of the weld seam material. ">"

During the welding process there is a large amount of hydrogen in the arc welding zone. It is well known that the hydrogen that dissolves in metal at high temperatures while of the crystallization process from this -> ". separates. Since the precipitation rate of Hydrogen is not high, pores will form in the weld seam material, and one will remain large amount of hydrogen, which affects the mechanical properties of the weld seam t> o substance has a detrimental effect. To prevent the hydrogen from dissolving in the weld seam material, the Powder composition according to the invention introduced in the stated amounts of sodium hexafluorosilicate. The introduction of the latter in an amount that is below the lower limit mentioned leads to no positive result. Exceeding the upper limit leads to the deterioration of the stable Burning the arc and thus for strong spraying of electrode metal.

The burnt magnesite is included in the above amount in the powder composition for cored wire electrodes introduced to increase the basicity of the welding slag, which, as is known, the liberation of the weld seam material of non-metal inclusions and also the reduction of its total oxygen content.

It was found that the lowering of the salary's of burnt magnesite in the powder composition according to the invention below that mentioned lower limit does not lead to a positive result. Exceeding the upper limit leads to a substantial increase in the spattering of electrode metal, since the content of metal droplets increases Oxygen is lowered, which leads to an increase in surface tension and an increase in droplet size leads.

To reduce the fluidity of the welding slag and the content of non-metallic oxide inclusions in the weld metal is included in the Powder composition electro corundum introduced. Introducing the latter in a crowd of less than 1.6% by weight leads to an increase in the fluidity of the welding slag, to deterioration the weld seam formation, whereby the welding performance is greatly reduced, and also to increase the Content of non-metallic oxide inclusions. Exceeding the upper limit of 7.5% by weight leads to a deterioration in the manufacturing properties of the slag - it comes to Increase in their melting point. During the welding process there is a lag in the melting speed the powder composition from which the core of the filler wire electrode is made the melting speed of the electrode jacket, which ultimately leads to contamination of the weld seam material due to non-metallic inclusions.

Furthermore, the essence of the present invention will become apparent from the detailed description of the embodiments explained.

example 1

Cored wire electrodes with a diameter of 1.6 mm were used during the welding process (conditionally referred to as A, B and C), the core of which consists of the powder composition obtained according to the invention is made. The steel jacket of the respective cored wire electrode was 33 percent by weight of the Total wetness of this electrode and had the following composition (in percent by weight): 0.05 carbon; 0.02 manganese; Trace silicon; 0.01 sulfur; 0.01 phosphorus.

The welding of steel specimens was carried out with their vertical position using the semi-automatic Procedure carried out with reverse polarity direct current.

Welding parameters:

Welding current 200 A.

Arc voltage 23 V

Carbon dioxide was used as the protective gas.
The steel to be welded with a thickness of 20

mm had the following composition (in percent by weight): 0.18 carbon; 0.45 manganese; 0.2 silicon; 0.02 sulfur; 0.015 phosphorus; Remainder iron.

The powder compositions from which the Cores of the flux-cored wire electrodes are listed in Table 1.

Table 1

Components of the powder composition of the
Electrode core

Cored wire electrode

ABC

Quantitative composition of the powder mixture of the electrode core (in percent by weight)

20th

Ruliikonzentrai 20.0 33.2 46.5 Ferromanganese 10.0 12.5 15.0 Ferrosilicon 1.30 2.0 2.60 Sodium hexafluoro- 1.0 2.1 3.3, 5 silicate Burnt magnesite 1.3 5.6 10.0 Corundum 1.6 4.1 6.7 Iron powder 64.6 40.5 15.9

By using the cored wire electrodes, the cores of which are made from the powder mixture of the aforementioned Composition are made, weld material obtained Mechanical tests to determine its notched impact strength became more specific Elongation and tensile strength, as well as a physico-chemical analysis to determine the content of the weld metal is subjected to gases such as oxygen, nitrogen and hydrogen.

The mechanical tests of the weld seam material were carried out according to the methods known per se carried out.

The content of oxygen, nitrogen and residual hydrogen in the weld metal was determined by the per se known vacuum melting process, and its content of diffusion hydrogen - according to the International Standard ISO 3690 determined.

To illustrate the advantages of the cored wire electrodes, the core of which is made from the powder composition according to the invention are comparative results of the mechanisms tests of the weld seam material, as well as comparison results the physical-chemical analysis to determine the gas content in the weld metal with the Application of a technical solution known per se, achieved analogous results (See U.S. Patent No. 38 00 120).

The stated results of the investigations carried out are listed in Tables 2 and 3.

30th

Table 2

Cored wire electrode

Tensile strength
MPa

Specific elongation

Notched impact strength (Charpy sample), J / cm ²
+20 ⁰ C -20 ° C

-40 ⁰ C

A 496

B 545

C 592

Cored wire electrode 638
according to US-PS
No. 38 00 120

29.5 30.2 22.5 20.5

112-122
137-174
9.82-11.1
73.6-88.4

51-56.7
62.7-115
37.3-41.2
24.6-29.4

34.4-41.2 56-83.5
34.4-36.2 7.73-7.73

Table 3

Cored wire electrode

Gas content
(in% by weight)

oxygen

Total content of residual and diffusion of hydrogen, ^cm3 / 100 g

Nitrogen hydrogen

A 0.058 0.012 5.5

B 0.036 0.008 3.5

C 0.044 0.007 4.0

Cored wire 0.09 0.016 12.0

electrode
according to US-PS
No. 38 00 120

From Table 2 it can be seen that the weld material, which was obtained using flux cored wires A, B and C having higher mechanical properties, SchweißnahtwerkstofT obtained than by using of US Pat. No. 38 00 120 filling produced as wire electrodes.

In addition, the efficiency of the welding process lies in the use of the aforementioned Cored wire electrodes up to 2.4 to 3.8 kg / h, which is about that 1.5 to 2 times higher than the welding performance when using those manufactured according to US Pat. No. 38 00 120 Cored wire electrodes is.

Through the filler wire electrodes, the core of which is made from the powder composition according to the invention is what makes you an excellent weld boom formation and good separability of the slag cover, as well as high resistance to Hot cracks and a low gas content are achieved.

Example 2

During the welding process, cored wire electrodes with a diameter of 2.2 mm were used.

Wendel (conditionally referred to as Λ. B and C), whose core is made from the powder / composition obtained according to the invention. The steel shell of the respective Cored wire electrode made up 80 percent by weight of the total mass of this electrode and had the following Composition (in percent by weight): 0.07 carbon; 0.25 manganese; 0.1 silicon; 0.03 sulfur; 0.03 Phosphorus.

The welding of steel specimens was carried out in a vertical plane (side weld) of the semi-automatic process with direct current reverse poking carried out.

Welding parameters:

Welding current 350 A.

Arc voltage 27 V

Carbon dioxide was used as the protective gas.

The / u welded steel with a thickness of 20 mm had the following composition (in percent by weight): 0.18 carbon; 0.45 manganese; 0.2 silicon; 0.02 sulfur; 0.015 phosphorus; Remainder iron.

The powder compositions from which the cores of the mentioned filler wire electrodes are made are listed in Table 4 below.

Table -4

readsiiiulleik- the Piilver- / ιι · -.ιπιπκ "Μ \ ι.Ί / ιιηΐ! of the l-learning meme ·.

iilldr.ihlelectrndc

Quantitative reduction of the powder mixture
of the electrode core
(in (iewkhlspro / enl)

Rutilcon / entrat 30.0 38th? 47.0 Ferromanganese P.5 20.C 22.5 Ferrosili / ium 2.0 4.0 6.0 Nat ι iumhexafluoro- 1.5 3.2 5.0 silikiit Burnt magnesite 2.0 6.0 10.0 Filektrokorund 2.5 5.0 7.5 Iron powder 44.5 23.3 2.0

The result of the application of the cored wire electrodes, whose cores are made from the powder mixture of the above Composition were made, weld seam material obtained was mechanical tests to determine its notched impact strength, specific elongation and tensile strength as well as a physico-chemical Subject to analysis to determine the content of gases such as oxygen, nitrogen and hydrogen in the weld metal.

The mechanical tests of the weld seam material were carried out according to methods known per se.

The oxygen content of the weld metal. Nitrogen and residual hydrogen were after what is known per se Vacuum melting process, and its content of diffusion hydrogen - according to the international Standard ISO 3690 determined.

The results of the mechanical tests carried out are shown in Table 5.

Table 5

Cored wire electrode

Tensile strength
MPa

Specific elongation

Notched impact strength (Charpy sample), J / cmrr
+20 ⁰ C -20 ⁰ C

-40 ⁰ C

A. 521 28.5 103-110 44.1-52 19.5-34.3 B. 558 29.2 123-135 63.8-68.5 34.3-39.2 C. 608 24.5 96.5-100 41.3-49 17.5-29.5

To illustrate the advantages of the cored wire electrodes, the core of which consists of the powder composition according to the invention is produced, are in the following Table 6 comparative results of the physicochemical Analysis to determine the gas content in the weld metal with the application of an known technical solution achieved analogous results listed (see US-PS No. 38 00 120).

Table b Gas content Ciesamtgchalt to rest t-wire (in weight- "'") and diffusion eleklrode Hydrogen, cmV100 g SauerslofT Nitrogen hydrogen 0.055 0.011 4.6 A. 0.040 0.010 3. « B. 0.044 0.011 5.2 C. 0.016 12 I llwire electrode according to I S-PS No. 38 (K) 120

From Tables 5 and 6 it can be seen that the Cored wire electrode, the core of which is made from the Powder collection is made. the SehweißnahlwerksiolT with high mechanical properties is obtained. In addition, the aforementioned filler wire electrodes are excellent Formation of weld seams and good indissolubility of the slag coating, as well as high resistance against cracks and a low gas content.

The performance of the welding process when using the aforementioned filler wire electrodes is 8 kg / h, which is 1.5 times higher than that Welding performance using cored wire electrodes manufactured according to US Pat. No. 38 00 120 is.

10

Carbon dioxide was used as the protective gas.

The steel to be welded with a thickness of 20 mm had the following composition (in percent by weight): 0.18 carbon; 0.45 manganese; 0.2 silicon: 0.02 sulfur; 0.015 phosphorus; Rest of Hisen.

The powder compositions from which the cores of the aforementioned cored wire electrodes are made are listed in Table 7.

Components of the l'uhor- / iisgenössLM / iing des
! ■ 'leklnulenkernes

I oil radiator electrode

set / ung of the powder mixture of the electrode tip
(in GewichNpro / cnl)

Rutile Concentrate 20.0 33.2 46.5 Fcrromangan 10.0 12.5 15.0 Ferrosilicon 1.30 2.0 2.60 Sodium he \ aflll (iro- 1.0 2.1 3.3 silicate Burnt magnesite 1.3 5.6 10.0 Corundum 1.6 4.1 6.7 Iron powder 64.8 40.5 15.9

Example 3

Cored wire electrodes with a diameter of 2.5 mm were used during the welding process (conditionally referred to as Λ, B and C), the core of which consists of the powder composition obtained according to the invention is made. The steel jacket of the respective cored wire electrode was 70 percent by weight of the Total mass of this electrode and had the following composition (in percent by weight): 0.08 carbon; 0.3 manganese; 0.12 silicon; 0.03 sulfur; 0.03 Phosphorus.

The welding of steel specimens was carried out in their normal position using the semi-automatic Procedure carried out with reverse polarity direct current.

Welding parameters:

Welding current 450 A.

Arc voltage 32 V

The weld material obtained by using the cored wire electrodes A. B and C became mechanical tests to determine its notched impact strength, specific elongation and tensile strength as well as a physical-chemical analysis to determine the content of the weld metal ar Gases, such as oxygen. Subjected to nitrogen and hydrogen.

The mechanical tests of the weld material were carried out according to methods known per se.

The content of the weld metal in oxygen, nitrogen and residual hydrogen was by the per se known vacuum melting method, and the Diffusion hydrogen content after international Standard ISO 3690 determined.

The results of the mechanical tests carried out on weld seam material are shown in Table 8 cited.

Table 8

Filler wire
electrode Tear
strength
MPa Specific
strain
% Notched impact strength
+20 ⁰ C (Charpy-Probc). J / cm ²
-20 ° C -40 ⁰ C A.
B.
C. 49.2
53.0
59.0 29.5
29.8
23.0 118-121
132-138
103-109 44.1-47
63.7-69.8
39.2-42.2 29.5-41.2
35.4-44.1
27.5-43.2

Il

The gas content of the weld metal is shown in Table 9.

Table 9

l'ülldniht- gas content total content of residual

eleklrode (ii wt%) lichem and diffusionv

wasserstolT. cmVlOO g

Oxygen nitrogen gas hydrogen

Λ 0.050 0.010 \ (l

B 0.034 0.008 3.6

C 0.041 0.012 4.1

Rilldrahl- 0.09 (). ()! () 12

electrode
according to US-PS
No. 38 00 120

From Table 8, it can be seen that by the filamentary wire electrodes. the cores of which are made from the powder composition according to the invention, the Weld seam material with high mechanical properties can be obtained. In addition, will excellent weld seam formation in normal weld position thanks to the filler wire electrodes mentioned achieved. Such weld seams have a good resistance to wear cracks and a low one Gas content.

The efficiency of the welding vonianges is 15 kg / h. The linear speeds of corner seam welding are dependent on the seam cathetus 50 to 80 m / h.

Example 4 (negative)

The welding was carried out essentially in the manner described in Example 1. While During the welding process, however, a filler wire electrode was used, the core of which was made from a powder composition was made, in which the components were contained in amounts that were in claim 2 below the specified lower limit values. The diameter of this filler wire electrode was 1.6 mm. The steel jacket of the cored wire electrode was 83 percent by weight of the total cored wire electrode mass and had the following composition (in percent by weight): 0.06 carbon; 0.23 manganese; 0.09 silicon; 0.02 sulfur; 0.02 phosphorus.

Welding parameters:

Welding current
Arc voltage

450 A
36 V

The powder composition of the mentioned cored wire electrode is given below:

Rutile concentrate 19.5 Ferromanganese 9.8 Ferrosilicon 1.0 Sodium hexafluorosilicate 0.8 Burnt magnesite 1.2 Corundum 1.4 Iron powder remaining

Below are the results of the mechanical tests carried out on the weld material listed:

Tensile Strength, MPa 460 Specific elongation, "h 24.0 Impact / strength (Charpy-Probc), J / cm ² : at +20 ⁰ C 71-73.5 at -20 ⁰ C 19.6-22.6 at -40 ⁰ C 11.7-14.7

From the above-mentioned results of the mechanical tests it can be seen that when using flux-cored wire electrodes with the above-mentioned powder accumulation during welding, the weld seam material with deteriorated mechanical properties is formed and its tendency to pore and crack is increased . D.ir üuei iiiiiuus kummi CMUi VeisciiiecMieiutii; iici Si.imii ity of burning the arc and / ur enlarging the fuel of electrode metal.

Example 5 (negative)

The welding was essentially the same as in the example 3 performed in the manner described. However, a filler wire electrode was used during the welding process used, in which the constituents were contained in amounts, which in the claim 2 exceed the upper limit values specified. The diameter of this filler wire electrode was 2.5 mm. The steel jacket of the cored wire electrode was 70 percent by weight of the total cored wire electrode mass and had the following composition (in percent by weight): carbon - 0.08; Manganese 0.30; Silicon - 0.12; Sulfur - 0.030; Phosphorus 0.030.

Welding parameters:

Welding current 450 A.

Arc voltage 32 V

The powder composition of the cored wire electrode is given below:

Rutile concentrate 47.0 Ferromanganese 23.0 Ferrosilicon 6.2 Sodium hexafluorosilicate 5.2 Burnt magnesite 10.2 Corundum 7.7 Iron powder remaining

Below are the results of the mechanical tests carried out on the weld material to listed:

Tensile Strength, MPa 627 Specific elongation. % 19.5 Notched impact strength (Charpy sample), J / cm ² : at +20 ⁰ C 78.5-90 at -20 ⁰ C 16.7-19.6 at -40 ⁰ C 10.8-12.7

F_>; it can be seen that by increasing the salary of components of the powder / composition of the filling electrode core above that in the claim specified upper limit value the deterioration the swisslchnological

ten of the mentioned flux-cored wire electrode will. There is an increase in the spraying of electrode metal. to worsen the smoothness of welding and /: i reduction of plastic Characteristic data of the weld seam.

Claims (2)

Patent claims: 1, powder composition for filler wire electrodes for gas-shielded welding and gas-shielded deposition welding of steels, containing rutile concentrate, ferromanganese. Fenosilicon, baked Magnesite and iron powder, characterized in that they also contain the following ingredients contains: (a) sodium hexafluorosilicate, (b) Electric corundum. 2. Powder composition according to claim 1, characterized in that the components of the Powder composition contained in the following ratio (in percent by weight): Kl seam forming is guaranteed. The aluminum in The form of nitride is partially transferred to the weld seam material, which, as is already known, the threshold value of the cold brittleness of the weld seam material is shifted to the high temperature range. Therefore, the use of cored wire electrodes, the core of which is made of the powder composition mentioned, is limited. Also known are powder compositions for FOIldrahtelektroden whose cold brittleness threshold value is in the low temperature range (-20 ⁰ C). Cored wire electrodes, the core of which is made from the powder mixture of the following composition (in percent by weight), have better welding technological properties in CO _{2 welding and COj build-up welding of steels in spatial positions:}