JPH0475796A - Low hydrogen type coated arc welding electrode - Google Patents

Abstract

PURPOSE:To offer an arc welding electrode having good welding workability by coating a steel core wire with a coating material consisting specific weight % of mica, rutile, lime carbonate, fluorite, Fe-Mn, silica sand, org. matter, and iron powder and the balance water glass. CONSTITUTION:The coating material is constituted, by weight 4 to 10% at least one kind of mica or talc, 35 to 62% rutile, 9 to 30% lime carbonate 1 to 8% fluorite, 3 to 18% Fe-Mn, 1 to 15% silica sand, <=2% org. matter, and <=35% iron powder and the balance water glass. The steel core wire is coated with this coating material. The low hydrogen type coated arc welding electrode is constituted in such a manner. The pit resistance, blow hole resistance and crack resistance are obtd. in such a manner by using this welding electrode.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a low-hydrogen coated arc welding rod, which eliminates the occurrence of pits, especially in primer-coated steel sheets, by improving the coating material, and This invention relates to a low-hydrogen coated arc welding rod that exhibits good blowhole resistance and excellent welding workability. .

(Prior art) Recently, as land structures such as ships, bridges, and blunts have become larger, the use of 50kg class high-strength steel has increased.
1 Also, a large amount of primer coated steel plate is used. For this type of welding, low-hydrogen coated arc welding rods are generally not used.

Conventionally, among this type of welding rods, Ca CO3 and Ca F
Although the welding properties of welding rods containing 2 as the main component are good, on the other hand, they have disadvantages such as slag build-up, poor flag peeling, and convex bead shapes, resulting in poor welding workability. I'm at 7.

On the other hand, although the t-welding rod, which has MgCO3-Sio2-MgO as its main component, has considerably eliminated the drawbacks in terms of workability, it is still not perfect. For example, when welding primer-coated 41 steel plates, there is a disadvantage that bits cannot be avoided, especially in the corner welds.

Therefore, in order to eliminate this drawback, Ca CO3゜S
A welding rod with improved welding workability as described above by blending iO, T 102 and iron powder as main components has been disclosed in Japanese Patent Publication No. 49-204137.

However, according to the knowledge of the present inventors, it is difficult to say that the welding workability is significantly improved or better, and in particular, the bit resistance and blow pole resistance for primer-coated steel sheets are inferior.

Furthermore, in Japanese Patent Application Laid-open No. 50-56339, T I O2
It is disclosed that the amount of neem generated during welding is reduced by using a coating material mainly composed of CaCO3 and Sin, but according to the experiments of the present inventor, the amount of neem generated during welding is lower than that of the conventional one. Is there a reduction effect compared to Ca C03 Ca F 2-based coated arc welding rods?Is the essential welding workability improvement and pit resistance against primer-coated steel sheets the inventors' goals? The area has not been reached.

(Solved by the invention 1 - problems to be solved by the invention) The present invention improves welding workability, eliminates the occurrence of jitter bits on primer-coated steel sheets, prevents the occurrence of blowholes, and repairs after welding. The purpose of the present invention is to provide a low-hydrogen coated arc welding ring that eliminates the work involved.

(Means for Solving the Problems) In order to meet the above-mentioned demands, the present invention investigated various coating compositions17 and achieved good welding workability for primer-coated steel sheets and improved bit resistance and blowhole resistance. The gist is that at least one of mica or talc is mixed with 4-109o, rutile 35-62%,
Lime carbonate 9-30Qo, fluorite 1-B%. , Fe-Mn
3-18%, silica sand 1-15%, organic matter 2% or less, and iron powder 35? This is a low hydrogen-based coated arc welding rod characterized in that a steel core wire is coated with a coating material containing:

(Function) In view of the above-mentioned situation, the present inventors have been conducting intensive research on improving the welding workability and pitting resistance of low-hydrogen coated arc welding rods from the viewpoint of coating materials.

As a result, we have found a way to solve these problems by adding at least one type of hydrated mineral, talc, to the coating formulation whose main components are rutile, lime carbonate, and fluorite. The present invention was made based on the new knowledge that the welding workability is improved by the droplet transfer being in the form of a spray, and the crack resistance to primer-coated steel sheets is also significantly improved.

The constituent elements of the present invention will be explained below.

[Mica, talc]

Mica and talc are minerals that contain water of crystallization, and are added as a hydrogen source to weld metal.If the amount is less than 4%, there is a lack of +, which can cause bits and blowholes in primer-coated steel sheets, as well as impairing welding workability. Undercuts are likely to occur due to droplet migration.

On the other hand, if it exceeds 10%, welding workability is good, but the amount of hydrogen in the weld metal becomes excessive elJ, and cracking resistance deteriorates. In other words, in the standard of ``Low Hydrogen Coated Arc Welding Rod'', the amount of diffusible hydrogen is required to be 15 ml/100 g or less, so the upper limit was set at 109°.

[Rujiru]

Rutile is used as a slag generator, viscosity modifier and arc stabilizer. If it is less than 35%, the arc condition will be unstable and the re-arcing property will be poor.

On the other hand, if it exceeds 62%, the fluidity of the slag increases, and the slag gets entangled with the end of the welding rod during welding, damaging the bead shape.

Furthermore, the heat resistance of the coating material deteriorates, and the latter half of the welding rod during welding becomes burnt out, making welding defects such as blowholes and undercuts more likely to occur.

[Carbonated lime]

Lime carbonate adjusts the viscosity of the slag [7] and also acts with the gas generating agent [17]. If it is less than 9%, the effect of the gas generating agent is insufficient, and bits and blowholes are more likely to occur.

On the other hand, if it exceeds 30%, the arc becomes weak and a stick burning phenomenon is observed, and the encapsulation of the slag deteriorates, resulting in a convex bead shape in the horizontal fillet.

[Firefly stone]

Fluorite is used as a slag former and viscosity modifier. If it is less than 1%, bits and blowholes are likely to occur. On the other hand, 89. ．． If it exceeds the arc state or unstable state, 2-
The slag removal properties deteriorate.

(:Fe-Mn:l Fe-Mn is effective as a deoxidizing agent and an alloying agent.

If the temperature is less than 39°C, deoxidation will be insufficient and blow balls will occur. In addition, the mechanical properties of the weld metal deteriorate, and the strength and spread of the arc are impaired, resulting in poor bead shape.

On the other hand, if it exceeds 18%, there will be excessive deoxidation and bits will occur! : The weld metal also hardens and its cracking resistance deteriorates.

[silica sand]

Silica sand is used as a slag forming agent. If it is less than 1%, sufficient slag viscosity cannot be obtained, and the encapsulation of the slag in downward welding deteriorates, resulting in a bead or convex shape.

On the other hand, when it exceeds 1506, the viscosity of the slag increases significantly by 1 to 1.
7. Bits are generated] 7. If the coating becomes too deep, the arc state becomes unstable.

〔organic matter〕

If organic substances such as wood flour or dex I/phosphorus are used as coating aids, or if they are added in an amount exceeding 2%, the adhesion of the coating will deteriorate, which is not preferable.

[Iron powder]

Iron powder is added to improve welding efficiency at high lava speeds and to obtain good re-arc properties. If it exceeds 35%, the melting speed and re-arcing properties are maintained, but the amount of slag becomes insufficient, and the encapsulation of the slag deteriorates, resulting in poor bead shape.

(Example) After adding water glass to the coating materials having various compositions shown in Table 1 and performing wet mixing, CO, 07%, sio, 02
%, MnO, 49%, PO, 012%, 50.0
08? tl.

NO.0015% carbon steel core wire IIs Z 3523) with a diameter of 4 mm and an angle of 400 mm was coated using a 2-type coating machine at a maximum temperature of 400°C. After drying, coated arc welding rods were prepared, and each welding rod was subjected to a welding workability test on a primer-coated steel plate, a bit resistance test, a blowhole resistance test, and a crack resistance test.

Welding workability tests, bit resistance tests, blowhole resistance and cracking resistance tests were conducted using the following methods.

[Welding workability test] A 5M-50B steel plate having a thickness of 12.7 mm was assembled into a T shape, and vertical advancement welding (current 150 A) and horizontal fillet welding (current 170 A) were performed.

The evaluation criteria is that the welding workability in terms of droplet transfer state, arc stability, and slag removal property is better than that of conventional low-hydrogen coated arc welding rods mainly composed of CaC0-CaF2. , Those that do not change much are marked with an X.

[Resistance pips!・Blowhole resistance test 1 Wash primer was applied to 5M-50B steel so that the film thickness was about 30 knots, assembled into a T shape, and horizontal welding was performed by hand.

The blowhole resistance was evaluated according to the NK Steel Ship Regulations M&= (7.10% or less was marked ○, and 10% or less was marked X.

Regarding bit resistance, the entire length of the bead is thoroughly exposed.1. O mark is good for items in L, 1 or more occurred]
7. Mark the item with an X.

[Crack resistance test] JIS
Also evaluated by Z 3157 U-type weld cracking test.

Those with good cracking resistance or equivalent to the conventional low-hydrogen type wave-covered arc welding rods mainly composed of Ca CO - Ca F 2 are marked with an ○ mark, and those with poor cracking resistance are marked with an X mark and 17. These results are shown in Table 1. Note that the mark ○ indicates good quality and the mark X indicates poor quality.

[Diffusible Hydrogen Amount Test] In JIS Z 311g, a diffusible hydrogen n1 test was conducted with the ff screen removed.

In Table 1, τB-8 to B-23 are comparative examples, B1 to B-
7 is an example of the present invention.

The results of this test are discussed as shown below.

B-1 to B-7 are low hydrogen coatings that meet the requirements of the present invention.
When using an arc welding rod, all criteria were good.

B-8 has less mica, which generates bits and causes welding workability to trottle, resulting in undercuts.
The bead shape also deteriorated.

B-9 has a large amount of talc and an increased amount of diffusible hydrogen.

Ta. The cracking resistance was also poor. B-10 has less mica and talc, generates bits and has a rough arc.
When T-undercut is used, its blowhole resistance also deteriorates.

B-11 contained a large amount of mica and talc, and had good welding workability and an increased amount of diffusible hydrogen. The cracking resistance was also poor.

B-12 had no rutile ',1>, insufficient slag k, unstable arc, and poor bead shape.

B-13 has a lot of rutile, which increases the fluidity of the slag1-
2 times, the bead shape was bad < 17, and it was resistant to blow polls and undercuts.

B-14 had less lime carbonate, and the effectiveness of the gas generating agent was insufficient, resulting in bits and blowholes.

B-15 had a lot of lime carbonate, a lot of rough squirrel grass was generated, undercuts were formed, and the bead shape was poor.

B-16 had less fluorite, and bits and blowholes occurred.

B-17 has a lot of fluorite, which makes welding workability poor, especially the arc condition becomes unstable, and the slag flakes and deteriorates iJ:.

B-18 has less Fe-Mn, which causes bits and blowholes due to insufficient deoxidation, and the strength and spread of the arc are reduced, resulting in poor bead shape.1. :.

B-19 contains a large amount of Fe-Mn, and is excessively deoxidized, causing bits to form, hardening the weld metal, and deteriorating crack resistance.

B-20 has less silica sand, and the amount of slag and viscosity are insufficient.
~, the bead shape deteriorates.

B-21 has a lot of silica sand, and the viscosity of the slag increases 12,
Bits occur (2. The coating tube becomes deeper, the arc condition becomes unstable, and the bead shape becomes worse.

B-22 had a large amount of organic matter, the arc spray was strong, the arc was unstable, a lot of spatter was generated, and the shape of each bead was poor.

B-23 had too much iron powder, insufficient slag amount, and poor bead shape.

(Effects of the Invention) The present invention specifies the types of components that make up the coating material and sets the blending ratio of each component within a specific range. The present invention provides a low-hydrogen coated arc welding ring with good crackability and welding workability.

(7) By using the welding rod of the present invention, excellent welding workability, bit resistance, blowhole resistance, and cracking resistance can be obtained on primer-coated steel sheets, and high tensile strength The contribution to the field of welded construction using steel materials is extremely large.

Claims (1)

[Claims] 4 to 10% by weight of at least one of mica or talc (
(hereinafter expressed in %), rutile 35-62%, carbonate lime 9
~30% fluorite, 1~8% Fe-Mn, 3~18% Fe-Mn, 1~15% silica sand, 2% or less organic matter, and 35% or less iron powder, with the balance water glass on the steel core wire. A low hydrogen-based coated arc welding rod characterized by being coated.