JPS58128296A - Coated are welding electrode of low spattering - Google Patents

Abstract

PURPOSE:To provide a titled arc welding electrode which decreases the production of spatters during welding considerably by adding and contg. elements having affinity to oxygen in particular into a steel are wire of an existing welding electrode used for welding of mild steel. CONSTITUTION:The steel wire of the following compsn. is used for the core wire of a coated electrode of low spattering having existing materials consisting of a mixture of oxides, carbonates and silicates of various elements, org. materials, berrous alloys, etc. which make electric arc welding easy on the surface as wating material: The compsn. of the steel wire is formed by adding and contg. >=2 kinds among elements (deoxidizing elements) having affinity of oxygen, that is, Si, Mn, Al, Ti etc. into the existing compsn. If such arc welding electrode is used, the foaming of deposited metal is decreased, the production of spatters is decreased and arc phenomena are stabilized, whereby the workability of welding is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of a coated arc welding rod having a novel core metal composition.

Welding is widely used for various connections, adhesives, and fixings when constructing, expanding, or renovating buildings, but spatter scattered during the work rarely falls on combustible materials and causes fires. Therefore, from the viewpoint of disaster prevention, it is desired to reduce the amount of spatter generated or to establish measures to prevent the generated spatter from scattering. Among these, the former is the most fundamental and various attempts have been made. By the way, as a welding method, the so-called covered arc welding method using a covered welding rod is used in various industries because of its good workability, versatility, and simplicity. It is well known to use a welding current or to improve the power source to use a current with a large DC component. However, a decrease in welding current leads to a decrease in welding speed, which significantly reduces welding workability. On the other hand, improving the power supply for existing welding machines requires considerable expense, and there are many difficulties from a cost perspective.

In addition, there are attempts to change the chemical composition of the coating material for welding rods, since this affects spatter generation, but in general, the coating material is a mixture of various oxides, carbonates, silicates, and organic substances, and is extremely difficult to coat. It is complex, and there are many unknown points about its behavior, so its adjustment and selection must be informed by experience.
Appropriate selection of coating materials to reduce spatter generation is also often difficult in practice.

An object of the present invention is to provide a coated arc welding rod that can significantly reduce the amount of spatter generated during welding, in place of the prior art described above.

That is, in a certain welding method, various factors can be considered as causes of spatter generation, but among them, those related to the welding machine and those related to the welding rod are important. Of these, the latter type of welding rod is classified into factors caused by the coating material and the mandrel, but as described above, appropriate selection and adjustment of the coating material is often difficult in practice. On the other hand, the behavior of mandrels during melting, especially the chemical reactions of their constituent components, has been elucidated both experimentally and theoretically. By the way, a typical form of spatter generation during welding is that the carbon in the molten core metal reacts with oxygen infiltrated from the surrounding atmosphere, resulting in carbon monoxide or carbon dioxide gas forming bubbles within the molten metal. When the metal is formed and discharged to the outside, scattering of molten metal, that is, sputtering may occur. Therefore, one way to prevent this type of spatter is to capture oxygen infiltrating from the outside with an element that has an affinity for it and prevent it from bonding with carbon, thereby preventing the generation of carbon monoxide or carbon dioxide gas. As a result, the scattering of molten metal may be reduced. The inventors
Based on this theoretical idea, various elements that have a particular affinity for oxygen (hereinafter referred to as deoxidizing elements) are added to the mandrel of the welding rod used for existing mild steel welding, and the welding tip shape is As a result, I was able to confirm its effectiveness. As is well known in the field of steelmaking chemistry, the deoxidizing effect is greater when two or more elements are added than when a single element is added, but experiments have confirmed that the same effect is also found on spatter generation. It was done.

The lower limit of the additive amounts of the additive elements Sl, Mn, M, and Ti is that below this amount, the effect of reducing spatter is extremely weak, and the upper limit is that above this amount, the hardness increases.
In addition, work hardening is significant, making it difficult or time-consuming to process into a wire rod, and even if it is possible to process, the toughness of the welded part decreases after welding, deteriorating mechanical properties.

[Example 1] 35% illuminite, 16% potassium feldspar, 15% ferromanganese, 10% silica sand, 8% talc, 6% lime carbonate
, a welding rod with an outer diameter of 3.2 mm and a length of 350 mm was manufactured, with a so-called illuminite coating material made of 5% starch on the surface, and a core made of steel with the composition shown in the sample number in Table 1. The amount of spatter scattered during welding was measured. The welding machine is AC type,
The welding current was 130 A, the welding position was downward, five welding rods each having a length of 350 mm were bead-welded on a common steel plate, and the entire amount of spatter scattered around was collected and measured. The actual length of the welding rod consumed differs somewhat depending on the trial number, so comparisons between trial numbers are made using the amount of spatter per unit consumption length of 6i, which is the total amount of spatter divided by the total length of the consumed rod. The results are shown in Table 1.

From this, it can be seen that the welding rod with the metal core of this example reduces the amount of spatter generated compared to the conventional one, and has a remarkable effect, especially when a predetermined amount of Sl and Mn are added at the same time. .

Table 1 *Commercially available welding rod [Example 2] A welding rod with a wire diameter of 6.2 and having a coating material similar to that in Example 1 on the surface and having a core made of steel with the composition shown in Table 2. We manufactured one and measured the amount of spatter scattered during welding. The test, welding conditions, and evaluation method were all the same as in Example 1.

This shows that the amount of spatter generated can be further reduced by adding At and Ti in addition to Sl and Mn.

Table 2 [Example 3] Wire diameter 3.2 having a so-called lime-chaniya-based coating material containing about 60% or more of titanium oxide on the surface and using steel having the composition shown in Table 3 for flavoring as a core metal. A new welding rod was manufactured and the amount of spatter scattered during welding was measured. The welding conditions and evaluation method were all the same as in Example 1. This shows that even in the case of a lime-titania-based coating material, the welding rod having the metal core according to the present invention generates less spatter than the conventional welding rod.

7-Table 3 Same as above, since the target of the example was mainly a mild steel welding rod, C: 0.
Although it is set to 1% or less, it is also effective for welding rods whose core metal is steel containing 11% or more of thermal CO. In this case, the increase in C increases the chance of CO and co2 gas generation,
The amount of deoxidizing elements such as Mn, U, and Ti added is 0.1% or lessC.
It is desirable to increase the number compared to the case of .

In addition to the above-mentioned additive elements, Or and Zr have similar effects. As for Cr, remarkable effects are exhibited at 3% or more and Zr at 0.3% or more.

8- As is clear from the above examples, according to the coated arc welding rod of the present invention, since the steel wire of the core metal contains a sufficient amount of an element that has an affinity for oxygen, (1) Foaming is reduced and spatter generation is reduced. At the same time, the arc phenomenon is stabilized and welding workability is improved.

(2) In addition to the amount of spatter generated, the size of spatter is also reduced, reducing the risk of fire outbreak.

(3) It has the effect of improving the heat quality after welding, especially the appearance quality.

Continuation of page 1 0 shots: Nobuaki Tokono 44-1-30 Hitobune, Urayasu City ■Applicant: Kajima Corporation Motoakasaka-chome 2-7, Minato-ku, Tokyo 486-

Claims (1)

[Scope of Claims] 1. The surface of the metal core is coated with a substance consisting of a mixture of oxides of various elements, carbonates, silicates, organic substances, iron alloys, etc., which facilitates electric arc welding. A coated arc welding rod made of a steel wire, wherein the composition of the steel wire has an affinity for oxygen with the existing composition. 2. The composition of the steel wire is Si-1.0 to 2.0%, M
The low spatter coated arc welding rod according to claim 1, characterized in that it contains n0.8 to 2.7% or both, and has a CD of 1% or less. 6. The composition of the steel wire is Si1. [l~2.0%, Mn
Containing 0.8 to 2.5% of both or either one of them,
The low spatter coated arc welding rod according to claim 1, further comprising 3.4 to 6.0% Ag and a CD of 1% or less. 4. The composition of the steel wire is S]1.0 to 2. th, M
Claim 1, characterized in that it contains both or one of n 0.8 to 2.7%, further contains Ti 0.2 to 2.2%, and is C091% or less. Low spatter coated arc welding rod.