JPS61229494A - Low hydrogen type coated arc electrode - Google Patents

Abstract

PURPOSE:To prevent welding defects such as pits and blow holes by incorporating a specific ratio of an org. material and a specific ratio of ultra-fine particulate titanium oxide which is specified in particle size and quantity into a coating material. CONSTITUTION:This low hydrogen type coated electrode is formed by adding a binder to the coating material contg. 0.2-5wt% ultra-fine particulate titanium oxide consisting of >=95wt%<1mu particle size and <=0.5wt% org. material and coating such material on the outside periphery of a steel core wire. Such arc welding electrode is highly resistant to the dislodgment of the coating material and obviates the generation of the welding defects such as pits and blowholes arising from the dislodgment of the coating material. The rate of mending is therefore decreased and the welding working efficiency is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a low hydrogen-based coated arc welding rod with improved resistance to shedding of the coating material.

(Conventional technology) In general, the drop-off resistance of low-hydrogen coated arc welding rods is as follows.

It is often influenced by the type of slip agent that improves the fluidity of the coating during painting, the particle size structure of the coating, the drying temperature, and the concentration of the fixing agent. In order to improve the fluidity of the coating material during painting, mica and kaolin are used in non-low hydrogen type wave W arc welding rods.

Materials containing a large amount of crystal water, such as talc and bentonite, are used, but they increase the amount of hydrogen in the weld metal and cause cold cracking, so they cannot be applied to low-hydrogen coated arc welding rods. be. Therefore, in order to improve the fluidity of the coating material in a low-hydrogen coated arc welding rod, it is effective to add sodium alginate or CMC, which improves slipperiness and increases viscosity. It shows a tendency to carbonize from a drying temperature of about ℃ or higher,
3, which is the general drying temperature for low-hydrogen coated arc welding rods.
At 50 to 450°C, it completely carbonizes, and there is a problem that the bonding strength of the coating itself or the degree of adhesion between the coating and the core wire is weak, which deteriorates the shedding resistance. One possible way to improve the deterioration of strength and adhesion is to increase the concentration of the adhesive, but if the concentration of the adhesive is increased too much, it will tend to dry out when mixed with the coating material, which will actually deteriorate the fluidity of the coating material. There is a problem with making it happen. In addition, as a way to strengthen the bonding force of the coating material itself, it is thought that it is effective to a certain extent to widen the range of particle size composition of the coating material, although it is not a fundamental improvement measure.
Considering the particle size of each raw material used and its blending amount in accordance with the characteristics of the welding rod, leveling the particle size composition becomes a very difficult problem in reality.As mentioned above, low hydrogen coating In order to improve the falling-off resistance of arc welding rods, it is necessary to find a slipping agent that contains almost no crystal water and does not deteriorate the falling-off resistance.

Improving shedding resistance has been an important research topic in terms of preventing welding defects such as bits and blowholes caused by shedding of coating material and improving on-site welding work efficiency.

In order to solve the above-mentioned problems, as proposed in Japanese Patent Application Laid-open No. 102254/1983, coating particles with 10
~20μ particles 13~2296.30~60μ particles less than 10%, 105~149μ particles 13~22%
It is possible to prevent dry cracking and improve resistance to falling off, reducing labor at the manufacturing site.
A technique has been disclosed in which defects such as bits and blowholes are less likely to occur and good welding workability can be obtained.

However, according to the research results conducted by the present inventors, it is extremely difficult to fundamentally improve the drop-off resistance of low-hydrogen coated arc welding rods by simply leveling the particle size structure of the coating material. It was recognized that this method was difficult, and did not satisfy the inventors' goal of improving the drop-off resistance of non-low hydrogen-based coated arc welding rods and improving welding work efficiency. .

(Problems to be Solved by the Invention) An object of the present invention is to provide a low-hydrogen coated arc welding rod with good resistance to shedding of the coating material.

(Means for Solving the Problems) The present invention prevents the occurrence of welding defects such as bits and blowholes by using low-hydrogen coated arc welding with excellent drop-off resistance of the welding rod coating. At the same time, the purpose is to improve on-site welding work efficiency, and its gist is: ultrafine titanium oxide with 95% by weight or more of particles less than 1 μm; 0.2 to 5% by weight; organic matter: 0 .5
There is a low-hydrogen coated arc welding rod characterized by adding a fixing agent to a coating material containing less than % by weight and applying it to the outer periphery of a steel core wire.

(Function) The present invention is characterized by focusing on the influence of organic substances on the deterioration of shedding resistance, which improves the fluidity of the coating material, and by adding 0.5% by weight of organic substances.
Below, we have added 0.2 to 5% by weight of ultrafine titanium oxide in the coating material, which contains 95% by weight or more of non-grooves with a particle size of 1 μm], for low-hydrogen coated arc welding rods that require strict welding control. This prevents welding defects such as bits and blowholes caused by coating material falling off, and enables highly efficient on-site welding work.

The effects of each component in the present invention and the reason for limiting the amount of the components will be described below.

The ultra-fine titanium oxide in the coating material is different from the commonly used coarse-grained titanium oxide, and the ultrafine titanium oxide in the coating material is uniform when mixed with the adhesive.
At the same time, it has the property of completely covering and coating the surfaces of other particles due to its strong hiding power. This means that the ultrafine titanium oxide exists between other particles, and expands the spacing between other particles or penetrates into the interparticle voids to form a close-packed layer. Therefore, when mixed with the fixing agent, it cancels the frictional energy of other particles and makes the fluidity of the coating extremely good during painting, and it also combines the organic substances added to the coating as a slipping agent. It was found that the fluidity was improved to an equal or greater degree, and it became possible to significantly reduce the amount of organic matter that degrades shedding resistance. On the other hand, as mentioned above, ultrafine titanium oxide improves the fluidity of the coating material by expanding the spacing between other particles or penetrating into the spaces between particles to form a close-packed layer, that is, causing a swelling phenomenon. However, if too much is added, water glass, which is an adhesion agent, will be embossed onto the coating surface after the welding rod is coated, making it easier for the welding rods to adhere to each other, which may cause adhesive cracks in the coating during the drying process. In addition, it is easy to get scratched during conveyance of the comparer, which causes a decrease in yield.

In this way, the addition of ultrafine titanium oxide has contradictory effects in terms of improving the fluidity of the coating without deteriorating the shedding resistance and improving the productivity after painting. The optimum range of ultrafine titanium oxide was investigated by making various test rods.

[Dropout test method]

6.0 x 700 in a container of 80 x 320 x 920
12 welding rods (approximately 3 mm) were inserted into the tube and rotated by a drive device at a speed of 30 rpm for 3 minutes to apply impact, and then the shedding rate of the coating material was investigated.

However, Wl: Coating weight of the sample bar before the test W3; Coating weight of the sample bar after the test The evaluation of the sample bar was conducted by investigating the shedding rate, fluidity of the coating material, and the presence or absence of adhesion cracks and scratches on the coating. Comprehensive evaluation was performed on three levels: 0 mark), slightly poor (Δ mark), and poor (x mark), and the results shown in FIG. 1 were obtained. However, regarding the dropout rate, 3 inches or less was considered good.

Table 1 shows the particle size distribution of the ultra-fine shell titanium oxide used in this test. Table 2 shows the basic formulation of the test welding rods.

Figure 1 shows the investigation results of the relationship between the ultrafine titanium oxide content of each test welding rod in Table 2 and the evaluation of the test welding rod. is 0.2%
When the welding rod was less than 100%, the drop-off resistance was good for all of the welding rods tested, but due to poor flowability of the coating material, eccentricity of the welding rod occurred frequently and the yield decreased. On the other hand, if it exceeds 5%, the fluidity of the coating material will be extremely good without deteriorating the drop-off resistance, but the coating surface will be easily scratched as the coating pressure decreases, and the welding rods will adhere to each other, causing problems when drying. It was found that 51 seconds should be the upper limit because adhesive cracking of the coating occurred.

[Organic matter = 0.5 weight or less] In low hydrogen-based coated arc welding rods, the amount of organic matter added as a lubricant varies slightly depending on the other raw materials blended, but it is recommended that 1.51 or more is added. Common.

However, in the present invention.

By adding 10.2 to 5% by weight of the aforementioned ultrafine titanium oxide, the fluidity of the coating material will not deteriorate even if the amount of organic matter added is 0.51% or less, and the shedding resistance will be good.
When the ratio exceeds 5, the drop resistance deteriorates rapidly. Therefore, the amount added should be less than 6.5%.

Since the low-hydrogen coated arc welding rod of the present invention is constructed as described above, it has excellent resistance to shedding of the coating material, and welding defects such as pits and blowholes due to shedding of the coating material do not occur. A low-hydrogen-based coated arc welding rod was obtained that satisfies the demands of on-site welders who want to reduce the rework rate as much as possible and improve welding work efficiency.

(Example) Next, the effects of the present invention will be illustrated in more detail with reference to Examples.

Test bars having the composition and structure shown in Table 3 were prepared. Using these, we evaluated the shedding resistance using the method shown below, and at the same time conducted a comprehensive evaluation of the presence or absence of adhesion cracks and scratches on the coating, as well as the fluidity of the coating material, and evaluated the results in three stages, as shown in Table 3. The following results were obtained. In addition, the evaluation in the table shows O mark; good Δ mark; slightly poor × mark; poor.

[Dropout test method]

6. In a container of 80mX 320mX 920wm. Owφ
Insert 12 x7005m welding rods (approx. 3kg),
After applying a shock by rotating at a speed of 30 rpm for 3 minutes using a drive device, the falling off of the coating material was investigated. Weight (dropping rate judgment criteria) 0 mark: Good (<3L) △ mark: Slightly poor (3 to 6%) × mark: Poor (>6%) In Table 3, (A-1) to (A-7) is a comparative example, (B
-1) to (B-4) show examples of the present invention.

Since (A-1) did not contain ultrafine titanium oxide, the fluidity of the coating material was poor, and the welding rod was eccentric due to frequent occurrences.

(A-2) had an excessive amount of organic matter, so the shedding resistance deteriorated. (A-3) had an excessive amount of ultrafine titanium oxide, which caused cracks in the adhesion of the coating, and it was extremely defective with many scratches. .

(A-4) had an excessive amount of ultrafine titanium oxide and organic matter, so it had poor resistance to falling off, and the coating had many adhesive cracks and scratches, which was extremely poor.

(A-5) was defective because ultrafine titanium oxide was not added, so the fluidity of the coating material was poor, and the welding rod was eccentric frequently.

(A-6) had an excessive amount of organic matter, so the shedding resistance deteriorated and was poor.

Since the content of titanium oxide (A-7) having a particle diameter of less than 1 μm was 95% by weight or less, the fluidity of the coating material was poor and it was poor.

(Effects of the Invention) As explained above, by using the low-hydrogen coated arc welding rod of the present invention, welding defects such as bits and blowholes caused by shedding of the coating material do not occur, so shipbuilding , it significantly improves the efficiency of on-site welding work related to steel frames and bridges, and has an extremely large industrial contribution.

[Brief explanation of the drawing]

Figure 1 is a graph showing the optimal blending amount of ultrafine titanium oxide that does not completely deteriorate the shedding resistance, improves the fluidity of the coating, and does not cause adhesive cracking or poor appearance of the coating. .

Claims (1)

[Claims] A fixing agent is added to a coating material containing 0.2 to 5% by weight of ultrafine titanium oxide with 95% by weight or more of particle diameters of less than 1 μm and 0.5% by weight or less of organic matter, and the adhesive is applied to the outer periphery of the steel core wire. A low hydrogen-based coated arc welding rod.