JPH07110431B2 - Low hydrogen system coated arc welding rod for weathering steel - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low hydrogen type coated arc welding rod for weathering steel, and more particularly to a low hydrogen type coated arc welding rod for weathering steel which is excellent in productivity during manufacturing.

[0002]

2. Description of the Related Art Hydrogen-based coated arc welding rods for weathering steel are alloy components having good corrosion resistance such as Cu and Cr in order to improve the corrosion resistance of the weld metal. Has been added to the coating.

However, in the production of the low hydrogen type coated arc welding rod for weathering steel, cracks are not observed on the surface of the coating material immediately after coating the outer periphery of the steel core wire with the coating material.
In the product inspection process after the drying process, defective products frequently occur due to cracks on the surface of the coating material, which significantly reduces productivity and poses a problem.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a low hydrogen type coated arc welding rod for weathering steel which is excellent in productivity during manufacturing.

[0005]

In order to investigate the above-mentioned cause, the present inventor tried the production by using the conventional coating material mixture and changing various coating and drying conditions, but good results were obtained. I couldn't do it. Furthermore, an examination was conducted by changing the coating composition other than the alloy components and the type of water glass, but no conspicuous result was obtained. Therefore, Cu and C, which are provided with weather resistance,
As a result of investigating the alloying components of r and Ni, it was found that the addition of Cu powder to the coating material is a major cause.

Since ancient times, water glass and Fe-Si have reacted,
It is known that cracking occurs in the coating during production because it generates gas, but when Cu is added to the coating,
It is presumed that Cu and Fe-Si form a local battery, so that the reaction is promoted, cracks occur on the surface of the coating material, and productivity is remarkably reduced.

[0007]

Based on such knowledge, the present inventor has conducted extensive studies on the addition mode of Cu, and as a result, the low hydrogen-based coated arc welding rod for weathering steel is coated with a coating agent. If the Cu core is not added and the steel core wire containing Cu or the steel core wire coated with Cu on the surface is used, cracking does not occur on the surface of the coating material and productivity is greatly improved. It was found to be extremely effective in making it happen.

However, in the steel core wire containing Cu, there was a tendency that the droplets did not move smoothly and became unstable. Therefore, as a result of studying addition of C, Si, Mn, Cr, Ni and the like as additional components, the present inventor
It has been found that the addition of the above has the effect of improving the migration of droplets. Furthermore, C has been found to have an appropriate content by adjusting the arc strength, and the present invention has been completed here.

That is, according to the present invention, as a steel core wire, in weight% of the steel core wire, C: 0.02 to 0.2%, Cu: 0.05 to 1.0%, Ni: 0.05 to 1 0.0% of the steel core wire is used, and the outer circumference of the steel core wire is coated with a coating material, and the coating material is a coating material in a weight percentage of CaCO ₃ : 35.0 to 60.0%, CaF _{2. : 7.5~24.5%, SiO 2: 3.5~11.0} %, TiO 2: 2.0~9.0%, Cu: a coating agent containing 0.1% or less, and , Mn: 0.2-3.5%, Si: 0.4-6.0%, and Cr: 0.05-1.3%, if necessary. A low-hydrogen-based coated arc welding rod for weathering steel is characterized by containing the following.

The present invention will be described in more detail below.

[0011]

[Action]

( Steel core wire ) First, the reasons for limiting the components of the steel core wire in the present invention will be described. In addition, a component content is a steel core wire total weight% here.

C: 0.02 to 0.2% When C in the steel core wire is less than 0.02%, the arc becomes too weak and fusion failure occurs. On the other hand, if it exceeds 0.2%, the arc becomes too strong, undercutting occurs, and spatter increases. Therefore, the amount of C in the steel core wire is 0.0
The range is 2 to 0.2%.

Cu: 0.05 to 1.0% Cu is a basic element that imparts weather resistance. However, if Cu in the steel core wire is less than 0.05%, the corrosion resistance of the weld metal is remarkably deteriorated, while if it exceeds 1.0%, the arc is weak, the rod is easily burned, and the weld metal sags. This makes it easier to operate the rod. Therefore, the amount of Cu in the steel core wire is set to the range of 0.05 to 1.0%. Note that Cu can be added to the steel core wire and / or plated on the steel core wire.

Ni: 0.05 to 1.0% Ni is effective in improving the migration of droplets, but if Ni in the steel core wire is less than 0.05%, the effect cannot be obtained. If it exceeds 1.0%, the stick tends to burn. Therefore, the amount of Ni in the steel core wire is set to the range of 0.05 to 1.0%.

( Coating agent ) Next, the reasons for limiting the components of the coating agent will be explained. Here, the component content is the total weight% of the coating material.

CaCO ₃ : 35.0 to 60.0% CaCO ₃ is the main component of the coating agent, and acts as a slag forming agent and a gas generating agent. But 3
If it is less than 5.0%, the amount of gas generated is insufficient, nitrogen and oxygen in the atmosphere cannot be sufficiently blocked, the pit resistance and blowhole resistance of the weld metal deteriorate, and the X-ray performance deteriorates significantly.
On the other hand, if it exceeds 60.0%, the arc becomes too weak, large-sized spatters frequently occur, and convex beads are formed. Therefore, the amount of CaCO ₃ in the coating agent is set to the range of 35.0 to 60.0%.

CaF ₂ : 7.5 to 24.5% CaF ₂ acts as a viscosity adjusting agent for slag. However, if it is less than 7.5%, the viscosity of the slag becomes too high, the bead is not uniformly covered with the slag, the bead appearance deteriorates, and pits occur. On the other hand, if it exceeds 24.5%, the viscosity of the slag is remarkably reduced, so that the slag is overly covered and the slag interferes with the slag, causing defects such as slag entrainment and fusion failure. Therefore, the amount of CaF ₂ in the coating agent is set to the range of 7.5 to 24.5%.

SiO ₂ : 3.5-11.0% SiO ₂ has a function as a slag forming agent, a viscosity adjusting agent, and a welding workability adjusting agent such as arc strength. However, if it is less than 3.5%, the viscosity of the slag decreases and
The amount of slag is insufficient, the slag does not cover the beads uniformly, and the arc is too weak and the crater spreads too small, resulting in defects such as markedly poor bead appearance, lack of familiarity, and insufficient penetration, which makes welding difficult. On the other hand, if it exceeds 11.0%, the slag amount and the viscosity increase, so that the slag does not escape with the arc force, and defects such as slag entrainment and fusion failure occur. Therefore, the amount of SiO ₂ in the coating agent is 3.5.
-11.0%.

TiO ₂ : 2.0 to 9.0% TiO ₂ has a function as a slag forming agent, a viscosity modifier, and a welding workability modifier such as arc stability. However, if it is less than 2.0%, the arc becomes unstable, undercutting occurs, and spatter increases. On the other hand, if it exceeds 9.0%, the arc becomes too weak and defects such as insufficient melting occur. Therefore, the amount of TiO ₂ in the coating agent is 2.0 to 9.
The range is 0%.

Cu: 0.1% or less Since Cu in the coating agent exceeds 0.1%, cracking of the coating agent occurs during production, so it is necessary to suppress it to 0.1% or less.

Further, in addition to defining the components of the steel core wire and the coating as described above, it is necessary to define the following components in the total weight of the rod.

Mn: 0.2-3.5% If the Mn in the total weight of the bar is less than 0.2%, deoxidation becomes insufficient and pits and blowholes are generated to deteriorate the X-ray performance. On the other hand, if it exceeds 3.5%, deoxidation becomes excessive, and pits and blow holes are generated to deteriorate X-ray performance.
Therefore, the amount of Mn in the total weight of the rod is set in the range of 0.2 to 3.5%. The Mn can be added in the steel core wire and / or in the coating material in the form of Fe-Mn, Fe-Si-Mn, metal Mn, or the like.

Si: 0.4 to 6.0% If the Si content in the total weight of the bar is less than 0.4%, the familiarity between the base metal and the weld metal is significantly deteriorated, and the weld metal easily sags, and the bead appearance Also becomes worse, and at the same time deoxidation becomes insufficient,
Pits and blowholes are generated and X-ray performance is degraded. On the other hand, if it exceeds 6.0%, excessive deoxidation will occur, and pits and blowholes will be generated, deteriorating the X-ray performance. Therefore, the amount of Si in the total weight of the rod is set to 0.4 to 6.0%. The method of adding Si is as follows:
Alternatively, it can be added to the coating material in the form of Fe-Si or Fe-Si-Mn.

Cr: 0.05 to 1.3% In the present invention, Cr can be added if necessary. However, if Cr in the total weight of the rod is less than 0.05%, the effect as weather resistance cannot be obtained. On the other hand, the upper limit is 1.3% in view of hardness of weld metal and welding work.

In order to adjust the welding workability such as the arc strength, the conformability, and the spread of the crater, BaCO ₃ ,
Carbonates such as MgCO ₃ can be added in suitable amounts to the coating. Further, in order to adjust the welding workability such as the strength of the arc and the stability of the arc, a suitable amount of silicate containing K ₂ O, Na ₂ O or the like can be added to the coating agent. Also, in order to improve the mechanical properties of the weld metal, Ni, M
Alloy components such as o, Ti, and B may be added to the coating agent in appropriate amounts, and iron powder may be added to the coating agent in appropriate amounts to improve efficiency.

Needless to say, the type of weather resistant steel to which the present invention can be applied is not limited.

Next, examples of the present invention will be described.

[0029]

【Example】

[Table 1] as well as

[Table 2] Prototypes of coated arc welding rods having various component compositions shown in (1) and (1) were examined for productivity during production, and welding workability and X-ray performance were examined by a welding test. The results are also shown in Table 2.

In the welding test, SMA was used as the base material.
400AW, SMA400AP, SMA430AW, S
MA490AP 4 steel types 20t × 150w × 600l (m
Using the test steel plate with the size of m), the groove shape shown in FIG.
Down: 160-170 Amp, Vertical: 130-150 Amp
The welding conditions were as follows. The back side was welded after gouging.

In the table, Nos. 1 to 12 are inventive examples, and the productivity, welding workability, and X-ray performance were all good.

On the other hand, Comparative Example No. 13 is an example in which Cu was added to the coating material in an amount of more than 0.1%, cracking occurred in the coating, and the productivity at the time of manufacturing the welding rod was significantly reduced.

In Comparative Example No. 14, since the C in the steel core wire was too high, the arc was too strong, the spatter increased, and the rod operation was difficult.

In Comparative Example No. 15, the arc was too weak because Cu in the steel core wire was too high, the rod burned, the bead drooped, and fusion failure occurred, and Mn occupies the total weight of the rod.
Is too high, pits are generated and X-ray performance is significantly deteriorated.

In Comparative Example No. 16, since Ni in the steel core wire was too high, the arc was weakened, and Si in the total weight of the bar was too low, so that it was not well compatible with the base metal and pits were generated. However, the X-ray performance was significantly deteriorated.

In Comparative Example No. 17, since C in the steel core wire was too low, the arc was weakened and a poor fusion occurred.
The line performance has deteriorated.

In Comparative Example No. 18, 0.1% Cu was added to the coating material.
Since it was added in excess of 1, the productivity at the time of manufacturing the welding rod was slightly reduced. Further, since CaCO ₃ is high and CaF ₂ is too low, the arc is weak, a convex bead is formed, pits are generated, and a defective fusion occurs, and the X-ray performance is significantly deteriorated.

In Comparative Example No. 19, 0.1% Cu was added to the coating material.
Since it was added in excess of 1, the productivity at the time of manufacturing the welding rod decreased. Further, CaCO ₃ was low, and CaF ₂ was too high, resulting in insufficient deoxidation, pits and blowholes were generated, slag was entrained, fusion failure occurred, and X-ray performance was significantly deteriorated.

In Comparative Example No. 20, since the SiO ₂ in the coating material was high and the TiO ₂ was low, the arc was weak, the arc became unstable, fusion failure occurred, and the X-ray performance was significantly deteriorated.
Moreover, since Cr occupies too much weight in the total weight of the rod, the welded portion becomes hard, which makes the welding process difficult.

In Comparative Example No. 21, since the SiO ₂ in the coating material was too high, slag was entrained, fusion failure occurred, and X-ray performance was significantly deteriorated. Moreover, since Cr contained in the total weight of the rod was low, the further required performance as weather resistance was not satisfied.

In Comparative Example No. 22, the content of TiO ₂ in the coating material was too high, and the Mn occupying the entire weight of the rod was low, so the arc was too weak, and poor melting occurred, causing blowholes.
The X-ray performance deteriorated significantly.

In Comparative Example No. 23, since the SiO ₂ in the coating material is low and the Si content in the total weight of the rod is too high, the arc is weak and the fitting is insufficient and the melting is insufficient. Further, pits and blowholes were generated due to excessive deoxidation, and the X-ray performance was significantly deteriorated.

[0043]

As described in detail above, according to the present invention,
It is possible to provide a low-hydrogen coated arc welding rod for weather resistant steel that has excellent productivity during manufacturing and has the required performance as a welding rod (welding workability, securing of weld metal without welding defects, etc.). .

[Brief description of drawings]

FIG. 1 is a diagram illustrating a groove shape in a welding test.

Claims (2)

[Claims] 1. As a steel core wire, in weight% of the steel core wire, C: 0.02 to 0.2%, Cu: 0.05 to 1.0%, Ni: 0.05 to 1.0%, using a steel wire containing, it covers the outer periphery of the steel core wire with a coating agent, the coating agent, a coating agent _{weight%, CaCO 3: 35.0~60.0%,} CaF 2: 7.5 .About.24.5%, SiO ₂ : 3.5 to 11.0%, TiO ₂ : 2.0 to 9.0%, Cu: 0.1% or less, and the total weight of the bar. %, Mn: 0.2-3.5%, Si: 0.4-6.0%, a low hydrogen-based coated arc welding rod for weathering steel. 2. The low hydrogen system coated arc welding rod for weathering steel according to claim 1, which contains Cr: 0.05 to 1.3% in the total weight% of the rod.