JPS6030597A - Coated electrode - Google Patents

Abstract

PURPOSE:To improve the resistance to breakage of flux cup in the stage of contact reignition and to improve welding quality and working efficiency by specifying the component contents of CaCO3, TiO2, SiO2, Fe-Mn, org. material and ultrafine granular iron powder in the compsn. of a coating material. CONSTITUTION:A coating material which consists principally of 10-30% CaCO3, 15-30% TiO2 (TiO2 consists of 1-5% titanium oxide and the balance a rutile- component), 15-30% SiO2, 4-13% Fe-Mn, 2-5% org. material and 20-40% ultrafine granular iron powder having >=80% <=325 mesh and is adequately compounded with a slag forming agent, deoxidizing agent and binder is prepd. Such coating material is coated on a steel core wire to form a coated electrode. Since fine granular iron powder is used for the coating material of such electrode, a reignition property is assured with a small amt. of said powder to be added. Resistance to breakage flux cup is satisfactory in this case.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coated arc welding rod, and more particularly, the present invention relates to a coated arc welding rod, and in particular, by improving the composition of the coating material, the re-arc property after arc interruption and the so-called "cup breakage property" can be greatly improved. This invention relates to an improved coated arc welding rod.

One of the important properties that a coated arc welding rod should have is re-arc properties. Conventionally, coated arc welding rods with high re-arc properties, such as those containing a large amount of iron powder or those based on titania, have been used. However, in recent years, since it has become mandatory for welding machines to be equipped with an electric shock prevention device, the no-load voltage on the secondary side of the welding machine is usually 80 to 90 V, but the electric shock prevention device As the voltage was lowered to about 20 V, it was necessary to restart the arc after interrupting the arc in this state.

In other words, the desired re-arc property is achieved by simply contacting the welding rod with the protective steel plate formed at the end after welding is interrupted.
It is now necessary to be able to re-arc, and in this respect, coated arc welding rods, which were conventionally said to have good re-arcing properties, are no longer satisfactory as they are difficult to re-arc after the arc has been interrupted.

Although welding rods containing a large amount of iron powder or rutile have been considered, iron powder-based ones have a content of 50% or more, and are mainly used for fillets. However, it is not used as a so-called all-position welding rod that can weld in vertical or upward positions because of its poor workability.
Not yet. In addition, titania welding rods also have %'I'i0. f
Those designed to increase fi deteriorated in workability in vertical and upward positions due to increased slag viscosity, etc., and were impractical.

Another important property of coated arc welding rods is their ``susceptibility to cup defects.''

In other words, during re-arcing, if the rod end protection tube has completely cooled down and the electrical resistance becomes high, or if the steel plate surface is coated with rust, scale, shop primer, etc., the steel plate - rod end protection tube should be As the electrical resistance between the parts increases, contact re-arcing is poor and re-arcing is impossible, not only for welding machines equipped with an electric shock protector, but even for welding machines without one. It is. In such a case, the welding operator taps the protective tube against the steel plate, causing the protective tube to come off and exposing the welding rod core wire. By ET, the relay of the electric shock protector is activated, and re-arc is possible for the first time.

However, when the protective tube is missing, the coating material is only chipped to the extent that the core wire is slightly exposed due to hammering (1 cup missing is good), and the coating material is not significantly chipped due to the hammering. If the welding rod core wire is exposed more than necessary, the arc directionality and sufficient shielding effect will be impaired.
As a result, welding defects such as disturbed weld beads and generation of pores are likely to occur.

In this respect, conventional coated arc welding rods have not been satisfactory in terms of cup chipping. In order to overcome these drawbacks, the sacrificial deposit method and the backstep method have been adopted as methods to prevent welding defects during arc start, but either method is unreasonable depending on the welding location.

In addition, it is not possible to resume welding smoothly, and furthermore, neither method can be used for temporary attachment work such as boiling.

Under the above circumstances, there is currently a strong desire for the emergence of an innovative coated arc welding rod that can satisfy all of the properties.

Therefore, the present invention eliminates the above-mentioned permanent setting and enables contact re-arcing when welding is restarted after an interruption, regardless of the presence or absence of an electric shock protector, and in this case, the cup chipping is prevented with good resistance. Even when the protective tube is struck, the coating material is only chipped to the extent that the welding rod core wire is slightly exposed. Therefore, the labor and fatigue of the welding worker are greatly reduced, and the quality of the weld and work efficiency are improved. It is an object of the present invention to provide a novel coated arc welding rod that can significantly improve the properties of the coated arc welding rod. After repeated experiments,
It was completed based on the knowledge obtained from the analysis, and its gist is that 0aOO810-80%, Ti
e, 15-80% (however, TiO2 is titanium oxide 1-80%
5ch, and the rest is for rutile. ), Sin, 15~
8 (1, ye - Contains Mn 4-18%, organic matter 2-5%, and ultrafine iron powder 20-40- with a proportion of 825 mesh or less of 80% or more, and also contains a slag forming agent, a deoxidizing agent, and 1. The present invention provides a coated arc welding rod characterized in that a steel core wire is coated with a coating agent prepared by adding an appropriate amount of a coating agent.

The present invention will be explained in detail below.

First, in the present invention, the composition of the coating material is such that it contains a predetermined amount of a specific component, and the reason for this is as follows. However, if it is less than 10%, the amount of gas generated is small and the arc blowing force is weak, so penetration is small and the bead cannot spread. On the other hand, if it exceeds 80%, the arc blowing force is too strong In addition, since the slag fluidity increases and the bead appearance becomes poor, the content of caco8 is 10 to 8.
0% is necessary as a slag forming agent, but if it is less than 15%, the slag will lack viscosity and the bead shape will be poor, but if it exceeds 80%, the slag will become too thin. If the viscosity increases too much, it becomes easy to involve slag, and when the welding speed is increased, the slag followability becomes poor and undercuts are likely to occur, so the content of Tio is 15 to 80%.
Limited to a range of %.

However, Tio must contain 1 to 5 titanium oxide, with the remainder being rutile. That is, as shown in Table 1, titanium oxide is an ultrafine powder compared to rutile. Since cup chipping is a component that significantly improves the performance when hitting the protective tube during re-arcing, regulating the amount added is one of the most characteristic features of the present invention. However, if it is less than 1%, the effect will be reduced. Since the amount of coating material missing is too large, it is necessary to contain it in an amount of 1% or more. This makes it effective, and the core wire NH by hitting! Since the r length is appropriate, there will be no gaps that would cause welding defects during re-arcing. On the other hand, if it exceeds 5%, cracks in the coating tend to occur in the welded rod manufacturing process, so the amount of titanium oxide added is limited to a range of 1 to 5 tres.

sio is a necessary component to adjust the fluidity of the slag, but if it is less than 15%, the viscosity is low.

If 80% of the viscosity is super thin, the viscosity will increase too much, and in the case of vertical welding, undercuts will easily occur due to the reduced fluidity of the slag, and the bead appearance will also be poor.
The content of IO is limited to a range of 15 to 30%.OFe-Mn is necessary as a deoxidizing agent, but if it is less than 4%, its effect is insufficient and blowholes are likely to occur inside the bead. On the other hand, if it exceeds 18%, bits are likely to occur, so the content is limited to a range of 4 to 13 inches. Incidentally, instead of He-Mn, gold BHn corresponding to T may be added.

Organic substances are effective in improving arc phenomena such as arc stability, blowing, and spreading, and commonly used materials such as starch, dextrin, and cellulose are used, but if the organic substance is less than 2%, the arc becomes weak and the arc tends to break. , on the other hand, if it exceeds 5%,
If the spraying is too strong, it will impair the slag envelopment, making undercuts more likely to occur, and the stick burning will increase its toughness, making it impractical, so its content should be limited to a range of 2 to 5%. .

Iron powder is a necessary component for improving work efficiency such as increasing re-arc properties and welding speed, and regulating its particle size composition and addition amount is one of the most characteristic features of the present invention, along with titanium oxide. It is something that can be done.

In other words, the present inventor believes that if % fine-grained iron powder is used, a small amount is required to ensure re-arc properties, and therefore, in addition to special rods such as fillets, it can be used for vertical and upward work. Based on the knowledge that it can be applied to all posture bars where gender is important,
As shown in Table 2, it was decided to use ultrafine iron powder.

Table 2: Particle size structure of iron powder (% by weight) This iron powder is significantly finer than conventional iron powder, with 825 mesh or less accounting for 80% or more. The amount added should be in the range of 20 to 40%; if it is less than 20%, the contact re-arc property will be poor and the protective cylinder will have to be struck, so it will not be effective. If it exceeds the limit, the workability will be usable in downward or horizontal fillet positions, but the workability will be reduced in difficult positions such as vertical or upward, and the arc blowing force will be weaker, making it difficult to penetrate. The bead becomes shallow, the fluidity of the slag becomes unstable, and the bead shape and appearance deteriorate.

In addition to the above components, if necessary, AhO8,
Slag forming agents such as MgO1zro, BaO, Fe-8i,
A suitable amount of a deoxidizing agent such as Fe-A4 can also be added without impairing the effects of the present invention.

(Example) As shown in Table 8, 28 types of coated arc welding rods with various coating compositions were used in the test. Each welding rod is 4.0MφX 400 mtn, and the coating diameter is 6*'
It was set as Oismφ. The test board used was 1 of 5M-41.
2! XI 00X500 flat plate and T-shaped test plate.

For re-arc properties and cup missing properties, use a rod length of 10 on a flat plate.
The arc was interrupted by downward bead-on-plate welding at 18OA for 0 ms, and the possibility of re-arcing was examined (to investigate the degree of coating material missing when hammered). Vertical welding was performed and the quality of the welding was judged.

The test results are shown in Table-8. In addition, in the table, each test example is A-
G series - organized separately.

In the same table, the A series is a test example in which conventional iron powder was contained as the iron powder. In A-1 to A-8, rutile was conventionally combined with iron powder as a TiO2 source to gradually increase the rutile content, but all test examples were poor in both re-arc properties and cup chipping properties. In A-4, in which titanium oxide was added together with rutile, cup chipping was improved in terms of properties, but re-arc properties were still not improved and were poor.

The B series is a test example in which ultrafine iron powder was used as the iron powder and its content was varied. Ultrafine iron powder 2
B-1 with less than 0% has poor re-arc properties, while B-5 with more than 40% has good re-arc properties, but the arc blowing is weak and the slag fluidity is unstable, making it difficult to work. inferior in sex. On the other hand, Examples B-2 to B-4 of the present invention all showed good results in all test items.

The C series is a test example in which the content of aaao8 was varied; when the content of O-1 is less than 10%, the spraying is weak and there is no bead spreading, resulting in slightly poor workability; Sample No. 3 had increased slag fluidity and poor bead appearance. On the other hand, inventive example Q-2 had appropriate arc force and slag fluidity, and had good workability.

The D series is a test example in which the content of TiO2 is changed, that is, the content of rutile and titanium oxide as TiO2 sources is changed.
D-1 with less than 5% and D-3 with more than 80% both have poor workability due to slag fluidity. Ti
Although the total content as O2 is within the scope of the present invention, D-4 with no added titanium oxide or less than 1% titanium oxide
For D-5 and D-5, cup breakage during re-arcing is only a matter of separation, and for D-7, which contains more than 5% titanium oxide, coating cracks occur frequently during welding rod manufacturing, and therefore, when re-arcing One missing cup was inferior in quality, and the coating material was observed to fall off during welding.

On the other hand, inventive examples D-2 and D-6 showed good results in all respects.

The E series is a test example in which the content of sio was varied.Tear was less than 15% E-1 and more than 30% E-8.
In both cases, undercutting occurs due to slag fluidity, resulting in poor workability. On the other hand, E of the present invention example
-2 was good.

The F series is a test example in which the content of pe -Mn was varied, and F-1 with less than 4 inches had weak arc blowing and blowholes occurred, and F-8 with more than 18 inches
F-2 of the invention example had pits, whereas F-2 of the invention example had pits.
was in good condition.

The C series is a test example in which the content of organic matter was varied, and G-1 with less than 2% has a weak arc and no bead spreading, resulting in poor re-arc properties and workability, and G-1 with less than 2% has poor re-arc performance and workability.
In case of -8, the arc was strong during welding of the front end of the bar, and stick burn occurred in the latter half, resulting in poor workability. On the other hand, inventive example G-2 showed good test results.

As is clear from the above explanation, especially from the results of each test example, the coated arc welding rod prepared by adjusting the composition of the coating material according to the present invention can completely achieve the above-mentioned intended purpose, and is a breakthrough. It can be understood that this is a typical welding rod.

Claims (1)

[Claims] L 0a00 10-80%, TiO2 15-30% (
However, TiO2 is 1 to 5% titanium oxide, and the remainder is TiO2. ), 5io215-130%, Fe-
Contains 20 to 40% of ultrafine iron powder with a Mn of 4 to 1; 1%, 2 to 5 organic matter, and a proportion of 325 mesh or less of 80% or more, and appropriate amounts of a slag forming agent, a deoxidizing agent, and a fixing agent. A coated arc welding rod characterized by coating a steel core wire with a coating agent added thereto.