JPS6039479B2 - High cellulose coated arc welding rod - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coated arc welding rod, and more particularly to a kudzu cellulose-based coated arc welding rod that exhibits excellent welding workability in butt downward welding of fixed pipes and the like.

High cellulose coated arc welding has a strong arc force and produces a small amount of slag, so it is suitable for downward welding, and its arc properties also allow for easy welding.

In addition, extremely high welding speeds can be obtained at the initial solution stage in downward welding of fixed pipes, and this has long been used in Europe and America for on-site welding of pipelines. However, since the coating material contains a large amount of cellulose-based organic matter, the Joule heat during welding easily causes the organic matter in the unused portion of the coating material to decompose and burn, causing so-called stick burn. The disadvantage of using a section is that the arc becomes unstable during welding. Therefore, when using this type of welding rod, it is necessary to keep the welding current low compared to other coated arc welding rods such as low hydrogen type or illuminite type. However, in downward welding of pipelines, especially in initial shoulder prosthesis welding, it is necessary to use high current to ensure sufficient penetration and form an appropriate uranami beat. Because the lotus is pressed strongly against the root of the groove, it is easy to cause burns. If this happens, the arc will become unstable, causing poor port filling, and the under-wave bead will be disturbed, making it impossible to obtain a sound joint. Moreover, the effective length of the comb (the length of the comb that is actually used until it becomes unusable due to stick burn) is shortened in high-current castles, which is extremely uneconomical.
In addition, in the past, cellulose with short fibers of less than 100% was used as cellulose, so in downward welding of pipelines as described above, especially in first-layer uranami welding, the protective cylinder was pressed against the joint surface and welded. As a result, the cellulose fibers fall apart, causing the protective tube to collapse easily and cause a short circuit.

In this case, the welding rod must be replaced every time a short circuit occurs, which not only reduces efficiency but also increases the number of bead joints, making it impossible to perform uniform cold wave welding.
The present inventors focused on the above circumstances, and without impairing the features of high cellulose coated arc welding as described above,
In order to prevent extreme burns when using high currents, and also to prevent the protective tube from collapsing during initial layer welding, we conducted research mainly on the composition of coating materials and binders.

The present invention was completed as a result of such research, and consists of a high-cellulose coating material made by kneading coating material raw materials containing a large amount of cellulose with a sticky agent and coating the outer periphery of the steel core wire. In the coated arc welding rod, water glass with a Si02/Na20 molar ratio of 2.8 to 3.8 is used as a binder in a solid content of 10 to 21% based on the total weight of the coating material.
% (weight %: the same hereinafter) and 17 to 40% of cellulose containing 20 to 90% of long fiber cellulose of 10w or more in the coating material based on the total amount of cellulose,
Metallic enemy and/or Fe-Mn is 3-10% in terms of Mn, Tj02 is 8-25%, Si02 is 15-10%
30%, Mg○ 2-12%, Zr02 0.3-7%
, containing 1 to 17% iron oxide in terms of Fe0, and 0.3 to 4% in terms of crystallization water released at temperatures above 50,000 °C and amalgamated minerals containing crystal water released at temperatures above 50,000°C. ,
The weight ratio of the coating material to the total weight of the welded camellia is 0.1 to 0.1.
8, and the gist lies in that the content of C as an inorganic substance in the entire weld moat is set to 0.07 to 0.5%. The basis for the use and content setting of each component used in the present invention will be explained below.

■ Cellulose containing 20-90% of the total amount of cellulose with long fiber cellulose of 100W or more: 17-4
It plays the role of a 0% gas generating agent, and is an essential component to provide the original characteristics of high cellulose.
If it is less than %, deep lacquer penetration and a powerful arc cannot be obtained, making it impossible to obtain suitability for downward welding.

Moreover, if it exceeds 40%, it becomes impossible to prevent burnout even if other components are adjusted, and the arc becomes unstable. Furthermore, the fiber length of cellulose is an important requirement in the present invention, and is closely related to the type of protective tube of welded birch.

The long fibers of low or higher are necessary to prevent the protective cylinder from collapsing and short-circuiting, and if it is less than 20% of the total amount of cellulose, no effect will be seen. If it exceeds 90%, the slip of the coating material will become poor when it is applied to the welded core wire, and the coating material will also be difficult to squeeze, making the protective tube more likely to collapse.

By the way, by changing the blending amount of cellulose long fibers in the coating material indicated by reference numeral 8 in the experimental examples (Table 2) described later, steel core wire (
4. Vengeance? Table 1 shows the length of use until a short circuit occurs when a welding rod coated with a welding rod of 35 mm is used.

Table 1 The test method for effectively used rods was as follows.

Welding method: As shown in Fig. 3a, steel pipes of 11.1 ribs x 356 sides are butted together and welded downward in the direction of arrows EOA and B in Fig. 3b.

The shape of the groove is as shown in FIG. 4, and the end of the welded camphor arc is strongly pressed against the groove sheet portion to form a string, thereby forming the first layer of diamond-wave beads as shown in FIG. Welding conditions: current/
...DC/RP/14 Cape welding speed...3
0~40c/min As is clear from the above results, 100c/min
When cellulose containing 20 to 90% long fibers of & or more was used, the effective rod length was improved by more than 50% compared to cellulose containing only short fibers of less than 10 years.

■ Metal-poor 4n and/or Fe-Mn: 3 to 10% in terms of Mn It is an essential component as a deoxidizer, and if it is less than 3%, deoxidation is insufficient and clean port metal cannot be obtained. On the other hand, if it exceeds 10%, deoxidation becomes excessive and bits are likely to occur on the bead surface.

■ Ti02: 8-25% In order to stabilize the arc, it is necessary to contain 8% or more, but if it exceeds 25%, the arc force becomes weak and downward welding becomes difficult.

(2) S: 15 to 30% Si02 is a component mixed in as water glass and silicate mineral, and is an essential component to obtain an appropriate amount and viscosity of slag.

If it is less than 15%, the amount of slag produced will be insufficient and the elongation of the bead will be poor, making it impossible to obtain a healthy Uranami bead.

On the other hand, if it exceeds 30%, the amount of slag becomes too large and downward solubility becomes difficult. ■ Mg◯: 2 to 12% It has the effect of increasing slag removability and must be contained in an amount of 2% or more.

However, if it exceeds 12%, the fluidity of the slag becomes excessive and downward welding becomes difficult. ■ Zr02: 0.3 to 7% Contains 0.3% or more to improve arc concentration and gloss of the bead surface, improve compatibility between the port metal and base metal, and improve undercut resistance. It is necessary to do so.

If it exceeds 7%, the slag becomes dense and the peelability of the slag deteriorates. ■ Iron oxide: 1 to 17% in terms of Fe0. 1% to make the slag porous and improve its peelability, as well as to prevent the generation of bits due to excessive deoxidation.
or more must be contained.

If it exceeds 17%, the fluidity of the slag becomes excessive, making downward welding difficult.

■ Hydrous minerals containing crystal water released at 50,000 or more: 0.3 converted to crystal water released at 50,000 or more
~4% Hydrous minerals such as talc are used and contribute to arc spraying.

In order to effectively exhibit this effect, it must be added in an amount of 0.3% or more. However, if it exceeds 4%, the arc force decreases and the arc becomes unstable. The reason for specifying crystallization water as being released at temperatures above 500°C is that when water is released at less than 50,000°C, such as so-called adsorbed water, due to the high temperature during welding, the water is removed before the welding strands are consumed. This is because it is released into the atmosphere from the coated surface and has no effect on the arc. ■ Semi-binding agent: Si○/Na2
Water glass with a molar ratio of 2.8 to 3.8 and a solid content of 14 to 3.8
The molar ratio of Si2 to Na20 (hereinafter simply referred to as molar ratio) and the amount of 30% water glass are important requirements in the present invention, and are closely related to the scorching resistance of the welding rod.

That is, as will be described later, when the welding rods obtained by varying the molar ratio and blending amount of water glass were examined for scorch resistance, it was found that the performance was significantly improved within the above range.
The reason for this is thought to be that, as is clear from the experimental data described below, the coating obtained by combining the above preferred ranges has extremely good firmness after drying, and the combustion reaction of cellulose in the coating material is prolonged. . Incidentally, Figure 1 shows coating material raw material (
A coating material prepared by using long fibers (50% in cellulose) and varying the molar ratio and blending amount of water glass was coated with a key core wire (4
．． This figure shows the results of measuring the coating diameter after drying by passing it through a die with an inner diameter of 5.6.

As is clear from this result, the molar ratio is 2.8 to 3.8.
It has been confirmed that when a coating material containing 14 to 30% solid water glass is used, the diameter of the coating becomes considerably small and the coating becomes vertical. The reason for this tendency can be inferred from the results of microscopic observation of the cross section of the coating as follows. In other words, in the combination of the favorable molar ratio and blending amount, water glass is difficult to penetrate into the cellulose contained in a large amount in the coating material, is evenly distributed between the particles of the coating material raw material, and forms a film. This is thought to be because the particles become more slippery with each other, making it easier for the coating material to be densely packed, and also because the moisture in the water glass evaporates due to drying, causing the scorching phenomenon. However, low molar ratio water glass (molar ratio less than 2.8), which is most commonly used as a binder for coatings, is a cell. It easily penetrates into the base, and as a result, the cellulose undergoes a swelling phenomenon and the tightness of the coating becomes poor. In addition, water glass with a molar ratio exceeding 3.8 tends to gel, so that the water glass and the coating raw material are not compatible with each other, and the coating tends to fade during coating, resulting in poor coating continuity. On the other hand, if the water glass content is less than 14%, the water glass will not be sufficiently distributed between the coated Qishan raw material particles, which will not only weaken the bonding force between the raw material particles, but also cause the slippage between the raw material particles to become unstable. A space is created due to this, and the tightness of the coating becomes poor.

Additionally, if it exceeds 30%, the water glass coating will become too thick, and when it dries, the water glass coating will not only become brittle and reduce the binding force between raw material particles, but also cause the coating agent to slip too much, increasing the coating pressure. It becomes hard and the tightness of the coating deteriorates. Second
The figure is a graph showing the results of investigating the effective usable rod length (camphor scorch resistance) when performing downward welding using each of the welding rods obtained above. 14 to 3 glasses of water
The effective usability of welding rods using 0% is improved by more than 50% compared to conventional rods.

The test method for effective use horizontally was as follows. Welding method:
As shown in Fig. 3a, the 11.1 side t x 356 side steel pipes are butted together and welded downward in the direction of arrows A and B in Fig. 3b.

The shape of the groove is as shown in FIG. 4, and the tip of the welding rod is strongly pressed against the root of the groove and the string is applied to form an underwave bead as shown in FIG. Welding conditions: Current...
...DC・RP. 170A welding speed...30~40
c/min ■ Weight ratio of coating material to total amount of welding camphor (coating ratio): 0.1 to 0.18 This is a basic condition to facilitate downward welding of fixed pipes, and if it is less than 0.1 The function of the coating as a protective tube becomes insufficient and the arc becomes unstable.On the other hand, if it exceeds 0.18, the concentration of the arc decreases and hair bead formation becomes difficult. Downward weldability cannot be achieved.

■ Content of C as an inorganic substance in the whole welded camellia: 0.07
~0.5% [C% in steel' D wire] x [1-coverage ratio] 10 [
The C content calculated from [% of C as an inorganic substance in the coating material] x coating ratio converts the arc into a spray and contributes to improving the workability of first-layer underwave downward welding of fixed pipes.

If the C content is less than 0.07%, the above effects will not be effectively cured, and if it exceeds 0.5%, the cracking resistance of the weld metal will decrease. Note that C is added to the coating material in the form of high carbon Fe--Mn, graphite, or the like. The coated arc welding material of the present invention satisfies the requirements (1) to (3) above, but in addition, Ni, Q,
In order to improve the welding rate and workability, it is possible to mix an appropriate amount of alloying elements such as Mo, or add iron powder (usually 2% to the total amount of the coating material).
5% or less) can also be blended.

Furthermore, when obtaining a welding rod for an AC power source, the performance can be further improved by adding a small amount of K20 as an arc stabilizer. The present invention is constructed as described above, and in particular, by setting the blending amount of long-fiber cellulose and the molar ratio and blending amount of water glass used as a binding agent within specific ranges, high cellulose-based coated arc welding is possible. It improves stick burn resistance and the collapse of the protective tube, which were Haru's biggest drawbacks, and improves the workability of downward welding and joint performance.
By shortening the remaining rod length, wasteful consumption of welding rods can be significantly reduced.

Furthermore, by incorporating appropriate amounts of Z-2 and iron oxide, it is possible to prevent bits from occurring on the bead surface, improve the compatibility between the weld metal and the base metal, improve the appearance of the bead, and improve undercut resistance. , we were able to further improve the workability and joint performance of downward welding. Next, an experimental example will be shown.

Experimental Example A coating material having the composition shown in Table 2 was applied to a steel core wire (4.
A coated arc welding plate was manufactured by coating the outer periphery of a 350mm x 350cm plate to a predetermined coverage rate.

Using each of the obtained welding rods, base welding of a fixed tube was performed in the same manner as described above, and the welding conditions and effective usable rod length were examined. If welding becomes impossible due to stick burn during welding,
At that point, the welding rod was replaced with a new welding rod, welding was performed all around, and the average value of the effective usable length of the used welding rod was determined. The results are summarized in Table 2.

ship ship cape lagoon Climbing mackerel cloud lotus selection cloud led electricity Poison; Q Graves needle language lacquer nap electrostatic three steamer Consecutive victories Seed heavy electric [Deposited phosphorus]) ※※※※※※ From Table 2, the following can be considered.

'1} Code 12 is a typical example of a conventional high cellulose coated arc welding rod that uses low molar water glass as a binder, and the effective usable rod length is extremely short, and 42% of the welding rods are unused. wasted in the state.

Moreover, since the content of Feo is small and does not contain Z2, bits occur on the bead surface and undercuts occur.
'2} Reference numeral 13 is a comparative example in which the amount of Zr02 is too large, and the slag becomes dense and the peelability of the slag is extremely poor.

{3} Reference number 14 is a comparative example in which the content of Zr02 is low, and the arc concentration and bead appearance are poor.

Also, undercuts occur due to poor compatibility between the deposited metal and the base metal. '4- Code 15 is a comparative example in which the content of Fe○ is too low, and the slag peelability is poor and bits are generated on the bead surface.

'5 - Reference numeral 16 is a comparative example in which the content of Fe0 is too high, and the fluidity of the slag becomes excessive, and the slag becomes a hindrance, making the arc unstable and causing defects such as poor fusion.

{6) Reference numeral 17 is a comparative example with a low cellulose content, where the arc is weak and sufficient penetration cannot be obtained, and the bead elongation is poor due to insufficient slag amount, making it impossible to form a sound underwave bead.

'7) Comparative example in which the molar ratio of water glass is less than 2.8, and the stick burn resistance is poor and the effective rod length used is only about the same as that of conventional twill.

{81 Reference numeral 19 is a comparative example in which the coverage ratio is too small, and welding cannot be performed because the protective tube is weak and the arc is unstable.

(2) Reference number 20 is a comparative example in which the coverage ratio is too large, and the arc force is weak (due to insufficient penetration, a healthy Uranami bead is not formed).

10 Reference numeral 21 is a comparative example in which inorganic C in the welding layer is too small.Especially, the arc during initial layer welding is unstable, penetration is poor, and a healthy cold wave bead is not formed.

On the other hand, reference numeral 22 is a comparative example in which the amount of inorganic C is too high, and although a good back wave peadness is formed, bead cracking occurs. (11) Reference numeral 23 is a comparative example in which the amount of water glass blended is too large, and the effect of improving stick burn resistance is insufficient.

(12) On the other hand, numerals 1 to 11 are examples that satisfy all the requirements stipulated by the present invention, and the effective usage length is all over 30 yen, and the burn resistance is extremely good.
In addition, a sound Uranami bead can be formed without poor penetration. Brief explanation of the drawings Figures 1 and 2 are graphs showing the relationship between the molar ratio of water glass, the coating diameter after drying, and the effective usable rod length. Figures 3 to 5 are explanations showing the downward welding method adopted in the experiment. It is a diagram.

Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. A high-cellulose-based coated arc welding rod in which the outer periphery of a steel core wire is coated with a coating material prepared by kneading a coating material material containing a large amount of cellulose with a binder, in which SiO_ is used as a binder.
Water glass with a molar ratio of 2/Na_2O of 2.8 to 3.8 is used in a solid content of 14 to 30% by weight based on the total weight of the coating material.
In addition to containing long fiber cellulose of 100μ or more in the coating material, 20 to 90% by weight based on the total weight of cellulose.
It contains 17 to 40% by weight of cellulose, 3 to 10% by weight of metal Mn and/or Fe-Mn converted to Mn, 8 to 25% by weight of TiO_2, and 15 to 40% of SiO_2.
30% by weight, 2-12% by weight of MgO, 0% of ZrO_2
．． 3 to 7% by weight, 1 to 17% by weight in terms of iron oxide as FeO, 5% by weight of minerals containing crystal water released at temperatures above 500°C.
It contains 0.3 to 4% by weight in terms of crystallization water released at temperatures above 00°C, and the weight ratio of the coating material to the total weight of the welding rod is 0.1 to 0.18. A high cellulose-based coated arc welding rod, characterized in that the content of C as an inorganic substance is 0.07 to 0.5% by weight.