JPS6059079B2 - 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 coated arc welding rod in which a coating material containing iron powder is applied to the outer periphery of a core wire, which exhibits excellent welding workability. The present invention relates to a welding rod capable of forming a beautiful heat with excellent joint shape and isopodality.

In welding ships, bridges, buildings, etc., high-iron powder type coated arc welding rods containing a large amount of iron powder in the coating material are widely used for the purpose of improving work efficiency and heat shape.

This type of high-iron powder-based coated arc welding rod is mainly used for horizontal fillet welding, so its beautiful heat shape with excellent isopodality and ease of use are key performance points. &, W-, and same ↓★, those with good heat shape tend to be prone to unequal heat, while those with good isopodal heat tend to cause joint defects such as undercuts. It was hot.

In addition, there are some welding rods on the market that have relatively good isopodal properties and are less likely to cause joint defects, but these welding rods generally have extremely poor re-arc resistance and work efficiency is significantly reduced. As mentioned above, it is unsuitable as a welding rod for structures with a large number of welding points. In order to eliminate these drawbacks, it is possible to combine expensive alloying elements as auxiliary raw materials or develop complicated manufacturing methods, but the amount of this type of welding rod used is enormous. It must be able to be supplied in large quantities and at low cost, and even if improved techniques such as those described above are developed, they are not satisfactory in terms of practicality. The inventors of the present invention focused on the above-mentioned circumstances, and produced a rod that satisfies all performances such as heat shape, isopodality, welding workability, joint performance, etc., and supplies it in large quantities at the same low cost as conventional rods. Research has begun with the aim of developing three types of iron powder-based coated arc welding rods.

They focused on the fact that this type of welding rod contains a large amount of iron powder in the coating material, and found that the type and properties of the iron powder may have a considerable influence on the performance of the welding rod. Thinking about
We conducted intensive research to clarify the relationship between the properties and properties of iron powder and welding performance. As a result, we confirmed that the particle size and apparent density of iron powder have a significant impact on the performance of welding rods.
Based on this fact, we conducted further research and finally completed the present invention. That is, the structure of the coated arc welding rod according to the present invention is a coated arc welding rod in which a coating material containing 30 to 65% iron powder is applied to the outer periphery of the core wire.
Particles of which 25 to 80% are coarser than 100 mesh and have an apparent density of 3.0 to 4.0 Da/Cll or more;
The gist lies in the use of iron powder containing 5 to 25% particles that are finer than 200 mesh and whose apparent density is 2.0 to 2.911/CTl or less.

The structure and effects of the present invention will be explained below, focusing on the basis for limiting the grain size structure and apparent density of iron powder, which are characterized by the present invention. However, this does not limit the present invention, and all implementations that are compatible with the spirit of the above and below are included within the scope of the technology of the present invention.

Figure 1 shows the results of investigating the relationship between the particle size of iron powder contained in the coating material of D4327 series welding rods and isopod performance during horizontal fillet welding.

Here, the particle size of the iron powder was adjusted by classifying the iron powder into coarse particles and fine particles using a 100 mesh sieve, and by changing the mixing ratio of these particles, and the apparent density was 2.54y/CJ. Experiments were conducted using two types of iron powder of 3.21y/Crl.
As is clear from the results in Figure 1, if the content of particles coarser than 100 mesh is adjusted to 25% or more, excellent isopodal properties can be obtained for iron powder of any apparent density. I can do it.

In addition, the larger the apparent density, the better the isopodity. Generally speaking, isopodity is considered to be good if the difference in leg length is 17 m or less. Figure 2 also shows the coating material of the D4327 series welding rod. This figure shows the results of investigating the relationship between the apparent density of iron powder contained and the number of undercuts that occur in the upright side coachee part of the horizontal fillet weld.

However, in this experiment, the iron powder was classified into two with a 100 mesh sieve, and the mixing ratio of all particles coarser than 100 mesh was set to 40%. The apparent density is a value measured for particles coarser than 100 mesh before mixing. As is clear from this result, when the apparent density of particles coarser than 100 mesh becomes 3.0 y/al or more, the number of undercuts is significantly reduced.

Furthermore, as the iron powder content in the coating material decreases, the number of undercuts will decrease overall and the influence of the apparent density will be reduced, but the trend remains the same. From these results, 100
Coarse grain than mesh and apparent density 3.0f1/Crl
We are confident that by using iron powder containing 25% or more of the above, it is possible to obtain a coated arc welding rod with excellent isopod performance and joint performance.

However, based on current technology, it is difficult to industrially produce iron powder that is coarser than 100 mesh and has an apparent density exceeding 4.0y/CTl, so the apparent density of the iron powder is 3.
．． 0~4.0y/c! 1 range. FIG. 3 is a graph showing the relationship between the content of fine iron powder contained in the coating material and the re-arc property of the D4327 welding rod.

The iron powder particle size in this experiment was adjusted by dividing the iron powder into coarse particles and fine particles using a 200 mesh sieve, and changing the mixing ratio of the two. As a result, when the ratio of particles finer than 200 mesh is 5% or more, good re-arc properties can be reliably obtained, and this tendency is almost the same even when the content of iron powder is changed.

It is also confirmed that the higher the content of iron powder, the more the re-arc property improves overall. FIG. 4 is a graph showing the relationship between the apparent density of fine iron powder contained in the coating material and the re-arc property of the D4327 series welding rod.

In this experiment, iron powder whose particle size was adjusted in advance so that all particles finer than 200 mesh were constant (10%) was used. As is clear from this result, the smaller the apparent density of the fine iron powder, the better the re-arc property, and adjusting this apparent density to 2.9y/al or less will surely improve the re-arc property. I'll come.

In other words, even if iron powder contains about 10% of particles finer than 200 mesh, the apparent density is 2.9y/Cr.
If it exceeds 1.1, satisfactory re-arc performance cannot be obtained; however, if the grain is finer than 200 mesh and the apparent density is 2.
Since iron powder with a density less than 0y/Cll is extremely expensive and lacks practical use, the apparent density of the iron powder is 2.0 to 2.9f/Cll.
The range of d was determined. Incidentally, recent welding power sources are equipped with electric shock protectors for safety, and the degree of re-arc performance required varies depending on the type of electric shock protector. Third
, 4 In the experiment shown in Figure 4, a power supply equipped with a relatively highly sensitive electric shock preventer was used, but in this case, if the time required to re-arc after cutting the arc is 3 seconds or more, other power supplies may also be intermittent. Welding is possible, and there is a practical problem in terms of re-arc performance. We have confirmed that this is true. As is clear from these experimental results, 25% or more of the particles are coarser than 1100 mesh and have an apparent density of 3.0 to 4.0 da/d or more, and particles finer than 2200 mesh. If you use iron powder that contains particles with a particle content of 5% or more and an apparent density of 2.0 to 2.9 y/d or less at the same time, it will be possible to achieve the isopodity required for fillet welding, as well as beautiful and defect-free welding. It is possible to obtain a coated arc welding rod that simultaneously satisfies the bead shape free from cracks and the re-arc performance, which is a key point in welding workability.

However, if the content of the coarse grain/high apparent density iron powder mentioned in 1 above is too high, the coating properties when applying the coating material to the core wire tend to deteriorate, the coating speed decreases, and productivity deteriorates. Therefore, in the present invention, the upper limit of this content is set at 80%. Furthermore, if the content of the fine-grained, low-apparent-density iron powder mentioned in 2 above exceeds 25%, the re-arc performance will reach saturation and will not be improved any further.In fact, drying cracking will occur more easily, and this will cause the welding rod to be manufactured. Therefore, in the present invention, the upper limit is set at 25%. Furthermore, the reason why the iron powder content in the coating material was set at 30 to 65% is as follows. That is, the iron powder content is 30
%, no matter how the particle size structure and apparent density are adjusted, the re-arc performance hardly improves, and the effect of improving welding efficiency by using iron powder is no longer sufficiently exhibited. On the other hand, when the iron powder content exceeds 65%, the amount of slag decreases, making the crater unstable, making the weld bead convex, and undercutting is likely to occur. The present invention is roughly constructed as described above, and its effects are summarized as follows.

1. By adjusting the particle size structure and apparent density of iron powder, which is an essential component of iron powder-based coated arc welding rods, isopodity, bead shape, and re-arcing properties can all be satisfied.

2. Since there is no need to add special alloying elements, etc., and only the particle size and apparent density of the iron powder are adjusted, it can be supplied in large quantities at a price comparable to that of conventional iron powder-based coated arc welding rods.

3. Since the painting process etc. can be carried out in the same manner as in the conventional example, there are no manufacturing problems and no special equipment is required. Next, an explanation will be given using an experimental example.

Experimental Example A coated arc welding rod with a rod diameter of 5TnIrLφ was manufactured by applying a coating material containing iron powder with the particle size structure and apparent density shown in Table 1 to the core wire, and horizontal fillet welding and tests were performed on each rod. The leg properties, undercut resistance, re-arc properties, and productivity were investigated.

The results are summarized in Table 1. In Table 1, test bar N
O. 1 to 4 are iron powder iron monoxide based coated arc welding rods (D4327) using four types of commercially available iron powder as they are.
system).

In all cases, the apparent density of the iron powder in terms of particle size structure is outside the requirements of the present invention, and the performance of any one or more of re-arc property, undercut resistance, isopod property, and productivity is poor. Test rod No. Nos. 5 to 7 are examples in which two of the four types of commercially available iron powders were appropriately mixed, but none of them met the requirements of the present invention, and any one of the four types of performance did not meet the requirements of the present invention. is defective.

Test No. Examples 8 and 9 are examples in which the iron powder particle size structure and apparent density meet the requirements, but the content deviates from the requirements of the present invention, and the re-arc resistance or undercut resistance is poor.

Test bars No. 10 to No. 12 are all examples that satisfy the requirements of the present invention. lO is iron powder iron monoxide type (D432
7 series), NO. ll is iron powder-titania system (D4324 system), NO. 12 is an example of application to special type (D434O type) welding rods, which are excellent in all four types of performance.

- Brief description of the drawings Figures 1 to 4 are graphs showing the basis of numerical limitations in the present invention.

Claims (1)

[Scope of Claims] 1. A coated arc welding rod in which a coating material containing 30 to 65% iron powder is applied to the outer periphery of the core wire, the iron powder containing 1.
25 to 80% of the particles are coarser than 00 mesh and have an apparent density of 3.0 to 4 g/cm^3, and 5 to 25% of particles are finer than 200 mesh and have an apparent density of 3.0 to 4 g/cm^3. 2
．． A coated arc welding rod characterized in that it contains particles of 0 to 2.9 g/cm^3. 2. The welding rod used for horizontal fillet welding according to claim 1.