JPS58209499A - Low hydrogen covered arc welding rod - Google Patents

Abstract

PURPOSE:To stabilize an arc and to reduce spatters, by compounding fine particulate Fe-Mn, Fe-Si in a coating flux of a low hydrogen covered electrode thereby changing the droplet transfer in arc welding to spray transfer. CONSTITUTION:A flux of the compsn. consisting essentially of 1-25% SiO2, 0.5-20% TiO2, 12-60% carbonate such as CaCO3, MgCO3 or the like and 1- 25% fluoride such as CaF2, and contg. 1 or 2 kinds of 1-18% atomized Fe- Mn and 3-23% atomized Fe-Si of which >=55% has <=60 mesh grain sizes and <=45% iron powder is used as a coating material for a low hydrogen covered electrode. The electrode has good arc stability in the welding operation, produces less spatters per length of the electrode and forms excellent welding beads.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a low-hydrogen coated arc welding rod with improved welding properties, and relates to a low-hydrogen coated arc welding rod that exhibits properties such as spray transfer of a busy welding arc and low spatter. It's about sticks.

Low-hydrogen yarn 'Ml arc-covered welding rod (hereinafter simply referred to as low-hydrogen yarn welding rod) provides a male weld metal with good mechanical properties and crack resistance, so it is suitable for thick plates and places with large binding force. Although it is widely used as a welding material, it has been pointed out that it is inefficient compared to general welding rods such as silica illuminite and lime titania. The reason for this is believed to be not only the difference in the composition of the coating material, but also the difference in the shielding gas generated from the coating material. That is, the composition of the shielding gas generated by a general welding rod is N2. N20. (2) etc. are the mainstream, resulting in good arc stability, whereas with low-hydrogen welding rods, CO and CO2 are the mainstream, resulting in poor arc stability. . In addition, welding rods with a low water composition tend to have large droplets that cause globular migration or short-circuit migration (9. The drawback is that the number of spatter generation chambers increases per length of the rod used, which significantly impedes welding workability. was there.

The present invention was made in consideration of this situation, and aims to provide a low-hydrogen R1 contact rod that can realize spraying of droplet transfer and reduction of spatter. be.

The low-hydrogen welding rod of the present invention that has achieved the above object is one in which a 7-lux component consisting of a rib forming agent, a gas generating agent, etc. is applied to a steel wire along with a bonding agent. As, Si02: 1 to 25 Yu (vehicle volume, the same below) Ti
02: Contains O,F+~20 thionic acid salt: 12~60 group metal fluoride: 1~25 thi, further enriched with one or more types of atomized Fe-8i: 8~28 thi, and The key point is to use a material in which 55 or more of the total atomized powder particles are composed of fine particles that pass through 60 meshes.

5j02. TiO2, CaCO2, CaF2゜MgCO
3. A low-hydrogen welding rod coating Mi III containing BaCO3 and the like in a range partially overlapping with the above range is known, for example, from Japanese Patent Publication No. 55-42678. Atomized alloy steel powder (for example, 7e-Mn, Fe-5
i, pe-Ni, etc.) as an alloy t
It is known, for example, from Japanese Patent Publication No. Sho 54-80908, that the welding rod is broken around four core wires to form a general arc welding rod. However, the low hydrogen welding rod disclosed by the former publication.

(Based on the knowledge that the presence of IIF2 lowers the melting point of molten slag and increases the appearance of fume generation, it was decided to increase the amount of TiO2, which has the effect of improving the swab melting point, by at least twice that of CaF2 (7 & amount ratio). However, as a result, a problem arises in that # contact workability is reduced due to high melting point slag, and S i O2, B Fh C
03, M g C03 to find a compromise point by adjusting the composition of each component, there is a drawback that the degree of selection of flux raw materials is reduced, and the stability of the arc, which is a problem of the present invention, is Regarding the reduction of spatter, there are no notable results and no particular report has been made. On the other hand, the invention described in the latter publication takes advantage of the spherical shape of atomized alloy steel powder to improve the slipperiness of the coating material in the coating process of welding rods, thereby improving the adhesion of the coating material. However, in terms of the relationship with arc stability, it was only effective at preventing the coating material from cracking or breaking due to falling off.

In contrast, the present invention aims to achieve the same Kf4 contact workability without restricting the degree of freedom in selecting raw materials with respect to the blending ratio of Tj O2 and CaF2, the type of gabarate, etc. Especially atomized Ffl-Mn and atomized pe
-5i is intended to improve the droplet transfer state and achieve the effect of stabilizing the arc and reducing spatter. We also discovered that the particle size composition of all atomized powder particles plays an important role for the purpose of
The present invention was completed based on these comprehensive considerations.9 Therefore, in this specification, we will begin with a focus on the atomized powder and granules.

Fe-Mn and Fe-8i are general-purpose deoxidizers in low-hydrogen coating materials for welding rods. However, the present inventors reexamined its properties, types, storage, etc. from various angles, and found that Fe-M powder particles produced by the atomization method (regardless of water atomization or gas atomization)
n and pe-si, the former: 1-18φ, the latter two 3-2
Using particles in the range of B 2 and in which 55 or more of the total atomized particles are composed of fine grains that pass through 60 meshes will cause the droplet transfer state during arc welding to be spray transfer, and will prevent the generation of spatter. It was found that this is extremely important in suppressing the That is, 7 of the composition shown in Tables 1 and 2.
A fixing agent is added to the lux component to mix wires, and this is mixed into mild steel and U.
Coat the outer periphery of the wire and make a prototype welding rod (4.0 mm φX40 (1
As shown in Figure 3, a test plate (400 g' x 613
F7m"X 19")2 was mounted, and bead-on-plate welding was performed in the length direction while maintaining a forward leaning posture of 8f (AC).

18 (IA), 91 seven defeats sputter request on Oshikihani 1
Sentenced.

F e -M 1 (5F e-5i ata and content i
When we sought the relationship with t, we found that the fourth. The results shown in Figure 1 were obtained. The amount of scattered spatter was expressed as the total amount of collected spatter against the rectangular consumption length (cyn) of the welding rod (the same applies hereinafter).

As is clear from these results, atomized Fe
The amount of spatter collected is significantly smaller in those containing -Mn or atomized PE-5i (marked with *) than in the normally pulverized product (marked with ○).

However, the content of atomized Ffl-Mn is less than 1q6,
If the content of atomized PA-53 is less than 8 yen, not only will the effect of reducing the amount of spatter be insufficient, but the former will cause problems such as poor toughness of the weld metal, and the latter will cause blowholes due to insufficient deoxidation. is added, so we set the lower limits for the former as 196 or more and for the latter as 8 or more. On the other hand, when the former exceeds IB Excellent, the weld metal becomes hard and the cracking resistance decreases, and when the latter exceeds 28, the toughness of the weld metal decreases and the viscosity of the generated slag increases, causing it to thicken on the bead surface. Unevenness remains. For this reason, upper limits have been set for the former to be 18% or less, and for the latter to be 28% or less.

Table 8 is a graph showing the relationship between F6-Mn and PE-5i compounding material and welding workability.The basic components of the coating agent are: CaCU3 and MgCO3: 50%, SjO2:
2 'I' j 02: 2%, C11F2215 ratio, others = 2 to 29 ratio. Also, No. 11 is (A-1) to (A-6) in the same table.
The physical properties of weld metal when using , Figure 2 is (B-1)~
(B-6) Absorbed energy (vEo:K
g-m). That is, (A-1) has a large amount of sputtering due to less atomized Fe-Mn, and (A-6)
had excessive strength and hardness due to the large amount of atomized pe-Mn.

(B-1) has a large amount of spatter due to a small amount of atomized Fe-5i (, (B-6) has a low toughness due to a large amount of atomized Fe-5i. B-2)
~(B-5), (C-1)~(C-4>, (D
-t) to (D-4) are examples that satisfy the present invention.

+, a R Table ft1 Since Fe alloys such as FeNi and Fe-Mo are inherently limited in composition (e.g., coefficient 2 or less), they have little effect in contributing to reducing arc spray and spatter.

However, the inventors of the present invention were not satisfied with this, and as a result of further investigation into the transfer state of droplets and the occurrence of spatter, they found the following. That is, since the particle shape of atomized Fe-Mn, atomized FT3-si, etc. exhibits a spherical shape unlike a normal pulverized product, the spaces t* between particles are relatively small and constant. .

Therefore, the process in which the W coating is melted by arc heat and the process in which it melts and transfers to the base metal side is extremely clear, and the above-mentioned spray transfer form can be obtained. However, if the particle size distribution of the atomize varies greatly, Not only do their effects become unstable, but also problems arise when applying the coating. Table 4 is:
The particle size of all atomized powder and granules is shown as a welding test result when changing the particle size of 4.
In No. 4 (C-1 to C-5), in which 5 or more meshes are composed of fine grains that have passed through 60 meshes, the transfer of the droplets is spray-free and the generation of spatter is extremely small. It was completely accomplished. On the other hand, for those that do not satisfy these conditions (C 6 to 8), the transfer of droplets is discontinuous, and explosive transfer may occur instantaneously, leading to frequent spatter and concentration of arc. There was a defect that the sex became worse. In addition, a slight amount of shedding of the coating was observed in C.4 to C.5, and if you tried to avoid this problem,
Items that pass 0 mesh and do not pass 200 mesh account for 40 or more of the total atomized powder (C-1 to 8)
It was concluded that this is the most appropriate option. In other words, the finer the atomized powder is, the less spatter occurs, the transfer of droplets is affected, and the density of the coating becomes excessive, making it easy for the paint coating to fall off. On the other hand, if the number of coarse grains increases, the porosity in the coating material will become excessive, resulting in poor arc concentration and frequent spatter.The conditions for the welding work test in Table 4 are as follows:
The first appearance of spatter was measured according to the method shown in FIG.

<Bath contact conditions> Test plate: 8M50 (12txts”X75*mW
X45 (Irprs') Test rod: φX40 between 4.0
01 Embroidery 1 16 contact'rTl flow 2 150-170A Bath contact position: Downward bead-on-plate welding (horizontal fillet and vertical fillet) Next, regarding components other than atomized Fe-Mu (Fe-8 Rin) explain.

S! 02: 1 to 25 das It plays a major role as a slag-type bying agent, but if it is less than 1 part, the envelopment of the slag becomes excessive and the waveform of the bead becomes disordered, while if it exceeds 25 parts, the divine color of the slag becomes excessive. This makes it easier for the slag to dig into the bead.

T io2: 0.5 to 20 inches It gives an enviable luster to the exterior, but if it is less than 0.5 inches, its effect will not be exhibited, and on the other hand, if it exceeds 20 inches, the slag will pass through the ruts tightly. Peelability deteriorates.

Acid salts: 12 to 60 gas generating agents, which are blended as salts of CB, Mg, Ba, Sr, etc., but if less than 12, gas generation i decreases and blowholes occur due to insufficient shielding. On the other hand, if it exceeds 60%, the slag becomes highly basic.
The arc blow becomes weaker and the melting surface speed decreases.

Metal fluoride: A component that adjusts fluidity by the 61 nodes of one slig of 1 to 25. It is usually added as CaF2sAlF3, Nap, etc., but this effect is not exhibited in 1-inch cotton. As a result, the slag has a high viscosity and tends to form convex beads. On the other hand, if it exceeds 25, the fluidity of the slag will be excessive and a good bead shape will not be obtained.

In addition to the above-mentioned components, common components in coating materials such as alloying agents (Cu, Ni, Cr, Mo, Fe-7i
, Fe-A1. Mg, etc.), X9 group forming agent (A1203.
MgO, CaO, ZrO2, MnO, etc.), oxidizing agent (F
eO@F 8203, etc.), but iron powder in particular has the function of increasing RR efficiency and is listed as one of the recommended components.

However, if more than 45 inches of iron powder is added, the weld metal tends to drip down, especially in vertical position welding, so the upper limit is set at 45 degrees.

The coating components of the present invention may be added to a composition selectively formulated in accordance with the above description, with a fixing agent, preferably a bonding agent (such as S!02-K20-H20).

5i02-Na20 1120, 20-N to 5j02-
a 20 H20 etc.) is added and kneaded. After applying this to the outer circumference of the steel core wire,
Moisture is released as completely as possible by high temperature firing.

Since the low hydrogen thread-coated rod of the present invention is constructed as described above, it is possible to maintain the transfer of droplets in a spray state and to significantly reduce the amount of spatter generated.

Next, the present invention will be explained in detail.

A fixing agent is added to the flux components shown in Table 6 and kneaded, and this is made into a steel core wire.4. OLlImφ×
A 400mm1 welding rod was prototyped and #
Welding work characteristics and amount of spatter generation were measured. The results are shown in Table 7.

As shown in Table 5, in the present invention examples of J'・1 to 8, all conditions of the present invention were applied, so as shown in Table 7, good results were obtained in all items. It is being On the other hand, each of Comparative Examples S-1 to S-12 did not satisfy any of the conditions of the present invention, and therefore only inconvenient results were obtained.

First, in S-1.2, the blending ratio of 5102 is inappropriate, resulting in unstable slag encapsulation and poor bead shape.

Since S.8 contains too much TlO2, the slag becomes dense and the releasability deteriorates. Since S.4.5 has an inappropriate carbonate content, blowholes occur in the weld metal in S.4, and arc concentration is increased in S.5. Also, S.6゜7 has an inappropriate content of metal fluoride, so S.
A convex bead was formed in S.6, and slag entrainment occurred in S.7. Fe −M n &amp; Fe of S・8
-5i is a normally crushed product (the former corresponds to JIS-G2801, the latter corresponds to JIS-G2802).

The transfer of the droplets was globular, and the amount of spatter generated did not decrease. S・9 is atomized F 6-M
Since the content of M in t+ was small, the spray transfer of droplets was unstable, and the spatter reduction rate was also low. S.10 is an example in which the amount of atomized pe-Mnl and atomized Fe-5i is small, and not only the amount of spatter is not reduced, but also blowholes are generated in the weld metal. S・11.12 is 5-11 because the amount of atomized PE-8i is inappropriate.
Blowholes occurred in the sample S.12, and irregularities were formed on the bead surface in the sample S.12. In S・1・8, the particle size structure of the atomized powder was inappropriate, so the droplet migration pattern I! If p is discontinuous, explosive transition may occur instantaneously, and there are few places that contribute to reducing spatter generation and deposition.

[Brief explanation of drawings]

Figures 1 and 2 are graphs showing the effects of atomized Fe-Mn and Fe-51, Figure 8 is a sectional view showing the implementation status of test welding, and Figures 4 and 5 are graphs showing the effects of atomized Fe-Mn and Fe-51. 3 is a graph showing changes in the amount of spatter generated depending on the type and blending amount. Applicant Kobe Steel, Ltd.

Claims (1)

[Claims] +l) A low hydrogen-based coated arc welding rod in which a flux component consisting of a slag forming agent, a gas generating agent, etc. is applied to a mild steel core wire together with a fixing agent, wherein the flux is s io2
: 1 to 25 inches (weight%, same below), rio2:o
, rv ~ 20 t, subacid: 12 to 60 t, metal fluoride:
Contains 1 to 25 g as an essential component, and further contains atomized Fe-Mn: 1 to 18 g, atomized Fe-8i: 8 to
A low hydrogen-based coated arc welding rod containing one or two shelves of 28 meshes, and characterized in that 55 or more of the total atomized powder and granules are intercepted from fine grains passing through 60 meshes. (2. In claim 1, a low hydrogen-based coated arc welding rod 1 is composed of fine grains of 40 qb or more of all atomized powder particles passing through 25 to 60 meshes and not passing through 200 meshes, ( 3) In the scope of patent N1Ii, in item 1 or 2, the flux contains iron powder with a coefficient of 45 or less.1.