JPS60213398A - Low-hydrogen type coated arc welding electrode - Google Patents

Abstract

PURPOSE:To improve welding workability and to reduce the amt. of the fume to be generated by coating the coating material consisting of a prescribed ratio each of carbonate, metallic fluoride, MgO, TiO2, SiO2, Mn, KMg2.5(SiO)10F2, etc. on a carbon steel core wire. CONSTITUTION:The coating material contg., by weight %, 5-13% carbonate, 1-9% metallic fluoride, 6-18% MgO, 15-26% TiO2, 7-18% SiO2, 2-12% Mn, 1-6% KMg2.5(SiO)10F2, 15-50% Fe powder, 0.5-6% >=1 kind among Ti, Al, Mg, Si and SiC, 0.2-2.5% LiF and <=8% >=1 kind among Cu, Ni, Cr and Mo is prepd. A binder is added to such coating material and the material is coated on the carbon steel core wire, by which the titled electrode is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a coated arc welding rod, and more particularly to a low-hydrogen coated arc welding rod for reducing the amount of fume generated during welding. .

(Prior art and its problems) When welding high-strength steel plates, low-hydrogen welding rods are used to prevent delayed cracking. However, compared to other welding rods, this kind of welding rod is unfavorable in terms of the working environment because the fume generated during welding contains metal fluoride contained in the coating material. Particularly in horizontal fillet welding, labor-saving equipment such as gravity welders and low-angle welders are often used together. A single welder can use several labor-saving equipment at the same time, thus working in an environment with multiple arcs occurring at the same time.

Furthermore, the welding rods used in these labor-saving devices have a large diameter (5
, 0 to 80 mm), the current used naturally becomes high, and these effects combine to make the working environment extremely bad. Current countermeasures include providing partial or total ventilation or requiring welders to wear dust masks.

On the other hand, as a welding material that reduces the amount of fume generation, for example, KCaC is used as disclosed in Japanese Patent Application Laid-open No. 53-95846.
A low-hydrogen coated arc welding rod with a coating material mainly composed of O5 and CILF2 has been proposed, but this has poor welding workability, especially in horizontal fillet welding, where the bead shape becomes convex and fatigue strength deteriorates. Because of these drawbacks, it is not commonly used for horizontal fillet welding. Also, JP-A-54-1
Japanese Patent Application No. 27848 proposes a low-hydrogen coated arc welding rod to which fluoro-silicon mica is added for the purpose of improving welding workability and bead shape. However, although the addition of silicon mica over time has improved welding workability by adjusting the viscosity of the slag and improved the fatigue strength of the bead toe, the amount of fume generation has not been taken into account. Not yet.

(Objective of the Invention) The present invention provides a low-hydrogen coated arc welding rod that maintains excellent welding workability and bead shape while reducing the amount of fume generation, and also exhibits good bit resistance against paint-coated steel plates. Object of the invention (Structure of the invention) The gist of the present invention is carbonate: 5 to 13 carbonates, provided that MgC0.

Total carbonate excluding MnC05 is 6% or less, metal fluoride: 1-9%, MgO: 6-18%, TlO2: 15
~26chi, 5102 near ~18'Iy, Mn:
2 to 12%, fluoro-accumulative silicon mica (KMg2.5(
SIOlo) F2): 1 to 6 chi, Fe powder = 15 to 5
0%, Ti, At, Mg, Sl.

The total amount of one or more types of SjC is 0.5 to 6%, LiF:
0.2-2.5% and Cu + Ni, Cr
The total amount of one or more types of Mo is 8% or less, and if necessary, At20. : 6% or less and/or ZrO2:
A low hydrogen coated arc welding rod is made by adding a binder to a coating material containing 10 or less hydrogen and coating a carbon steel core wire.

Hereinafter, the pressure of the present invention will be explained in detail. conventional carbonate,
Simply reducing the amount of metal fluoride in the coating material of low-hydrogen coated arc welding rods, which are mainly made of metal valves, will not provide adequate slag viscosity and fluidity, resulting in poor welding workability. Moreover, it was found that the bit resistance of paint-coated steel sheets was significantly deteriorated.

As a result of various studies based on this knowledge, metal fluoride
MgO at 9%: 6-18%, TlO2: 15-26
%, 5 IO2: 7-18%, fluoro-silicon mica: 1
When the viscosity and fluidity of the slag are within the range of 6 to 6 inches, the slag's viscosity and fluidity are in the most favorable state, and good welding workability and bead shape can be obtained, and the amount of fumes generated can be significantly reduced. Ti r At r Mg as agent
+ The total of one or more types of St, SjC is 0.5 to 6
By blending within this range, it is possible to improve the bit resistance of paint-coated steel sheets.

Although the main points of the present invention are as described above, the individual components of the welding rod of the present invention will be explained next.

[Carbonate]

Carbonates include MgC0, MnCO3, and CaCO3.

BaCO3, Na2Co3. K2Co, , Li2
Co3 or the like is used and acts as a gas generating agent. That is, it is decomposed by arc heat pressure and generates CO2f gas, which has the effect of protecting the weld metal from the atmosphere and is effective in preventing cracking caused by hydrogen. If the total of one or more types of carbonates is less than 5 -, the effect as a gas generating agent is insufficient and blowholes and bits are likely to occur, but oxygen and nitrogen will increase in the weld metal and the mechanical properties of the weld metal will deteriorate. to degrade. On the other hand, if it is added in excess of 13 tres, the arc stability is poor, cis/l ivy increases, undercuts tend to occur, and the amount of fume generation increases. As the carbonate, MgCO, MnCO3 are preferable, but if the total amount of one or more carbonates other than these exceeds 6, the viscosity of the slag increases, the encapsulation property decreases, and the beads tend to become convex. .

[Metal fluoride]

As the metal fluoride, CaF2. MgF2. AlF2
゜NaμtF6. NaF, K2ZrF6, etc. are used. Metal fluorides contained in fume are harmful to the welding work environment.

Addition I
is an important point of the present invention. That is, regarding the relationship between the addition ratio of metal fluoride in the coating material of a low-hydrogen welding rod and the amount of fume generation, if the addition ratio exceeds 9%, the amount of fume generation increases rapidly, deteriorating the working environment. Therefore, it is necessary to keep the metal fluoride addition ratio to 9% or less. Furthermore, if less than 1 liter of hydrogen is added, the amount of diffusible hydrogen increases, resulting in a decrease in cracking resistance and pitting resistance against paint-coated steel sheets.

(MgO) MgO is a slag forming agent and a viscosity modifier, and is said to have good ability to remove cis slag. It also improves the basicity of the slag, which helps improve the mechanical properties of the weld metal.

However, if it is less than 6%, the above effect will not be significant18
If added in excess of 1, the stability of the arc will be poor, cis-batter will increase, and undercuts will also occur. In addition, the bead has a markedly convex shape. [TlO2] TiO2 is effective as a slag forming agent, a viscosity modifier, and an arc stabilizer. However, if it is less than 15 inches, the stability of the arc and the shape of the toe of the bead are poor, and the bead becomes non-uniform. On the other hand, if it is added in excess of 26 inches, the slag removability deteriorates, burns occur, and undercuts occur frequently.

[S10□] 5102 is effective as a slag forming agent and a viscosity modifier. However, if it is less than 7 inches, the slag tends to flow and is not well covered by the bead, so the bead shape becomes 6 inches. On the other hand, if more than 18 g is added, the viscosity of the slag becomes too high and it becomes difficult to weld.
Also, the slag will stick hard to the bead, making it difficult to remove the slag.

(Mn) Mn is effective as a deoxidizing agent and an alloying agent.

Furthermore, it is effective as a cis-slag generating agent due to the action of MnO produced as a deoxidation product. However, if it is less than 2 inches, deoxidation is insufficient and blowholes and pits are likely to occur. 1
If Mn is added in excess of 21, the amount of Mn in the weld metal becomes excessive, resulting in hardening of the weld metal, resulting in significant deterioration of mechanical properties and an increase in the amount of fumes generated. Mna may be added in the form of a ferroalloy.

〔Flu-day silicon mica〕

Fluorine mica f K) 14g, 5(s to
,. ) F2) acts as a slag viscosity modifier and can improve the fatigue strength of the dust bead toe in a small amount. However, if the amount is less than 1 inch, the effect of adding it is poor, and 6%
If it is added in excess of this amount, the viscosity of the slag will be too high and welding workability will deteriorate.

(Fe powder) Fe powder is added to improve the working egg weight, stabilize the arc, and properly adjust the amount of slag, but if it is less than 15 inches, the arc becomes unstable] and the amount of slag increases. Too much slag will cause the beads to sag. If more than 5 liters is added, the amount of slag will be insufficient and the beads will become convex. Fe powder may be added in the form of a ferroalloy.

[Ti, At, Mg, SI, 5iC) Ti, A
z, Mg, 81, and SiC have a strong deoxidizing effect. When coexisting with Mn, these elements act as deoxidizing agents and increase the yield of Mn in the weld metal. In addition, it is extremely effective in preventing pits on painted steel sheets. However, if the total of one or more types is less than 0.5 cm, pits will occur and the yield of Mn in the weld metal will decrease. If added in excess of TI, the mechanical properties of the weld metal will deteriorate significantly and the amount of fume generated will increase.

At r Mg r St is ferroalloy or 5t-At, )
L-Mg.

An alloy such as Ca-St may be added.

[: LIF] LiF is added as a moisture absorption inhibitor to coating materials, and is a component that cannot be substituted with other fluorides. A small amount is effective, but less than 0.2% does not sufficiently prevent moisture absorption in the coating material.

If added in excess of 2.5%, the protective tube at the tip of the welding rod tends to break during welding, making it impossible to perform satisfactory welding.

[Cu r Nl r Cr 2Mo] Cu, N
l + Cr r Mo is useful for improving the mechanical properties of weld metal, but its purpose can be achieved if the total amount of one or more of them is 8% or less. Cu + Nl + Cr + Mo may be added in the form of a ferroalloy.

In the present invention, the above-mentioned components are essential components of the coating material, but the following components may be added as necessary.

(ht2o, ) At203 has the effect of improving slag removability, but if it is added in excess of 6 inches, the sluggishness deteriorates.

[zrO2] ZrO2 & Yu is effective as a slag viscosity control agent at high and low temperatures, but if more than 10% is added, the slag viscosity becomes too high and beads become convex.Composition of the coating material used in the present invention are as described above, except for the above-mentioned components, which are the same as ordinary low-hydrogen coated arc welding rods, and if necessary, an arc stabilizer other than the above, a slag forming agent, and water glass as a binder may be added.

Next, the effects of the present invention will be explained in more detail with reference to Examples.

(Example) As shown in Table 1, an appropriate amount of water glass was mixed into a coating material with various compositions, and this was applied to a carbon steel core wire (JIS G 35231 class No. 1) of 6.0 mm φ x 700 m1. Covered arc welding rods were prepared, and each welding rod was subjected to a welding workability test (arc condition, slag encapsulation, bead shape), a pit test, and a measurement of the amount of smoke 4 generated. However, the welding workability test and pit test were conducted on welded products according to the welding conditions shown in Table 2. The amount of heat generation is measured in the third
JIS Z39 for items welded according to the welding conditions in the table.
Measurement was performed according to the method for measuring total fume amount of 30R coated arc welding rod. The results are shown in Table 4. Tables 1 and 4
In the table, A-1 to A-10 are examples of the present invention, B-1 to B-
20 is a comparative example. In Table 4, ○ indicates good condition.
A Δ mark indicates a slight defect, and an x mark indicates a defect. In particular, the ○ mark for the amount of fume generation is less than 350111 min, and the Δ mark is 350 min.
~400 Ill/min, X mark is 40011+9/m
The cases where the value exceeds in are shown in each case.

As a result of this test, A-1 to A-10 satisfied the requirements of the present invention, had excellent welding workability and excellent pit and torment resistance, and also had a reduced amount of fume generation.

B-1 to B-20 lack any of the requirements specified in the present invention, and cannot achieve the purpose of the present invention as shown below.

B-1 and B-2 are those in which the amount of carbonate is outside the specified range and is insufficient (B-1) u, f The effect as a gas generator is insufficient and bits are generated, and if there is too much (B-1) In case of -2), the arc stability is poor and CD undercut occurs, and the amount of heam generation also increases. B-3 is MgC0s r Mn
If the content of carbonates other than COs exceeds 6%, the encapsulation property decreases and the beads become convex.

In B-4 and B-5, the metal fluoride content is outside the specified range, and in the case of insufficient metal fluoride (B-4), the anti-pitting effect on the painted steel sheet is insufficient and a large number of pits occur. If the amount is too large (B-5), the amount of heat generated increases and the bead shape becomes convex.

In B-6 and E-7, the MgO content is outside the specified range, and when it is insufficient (B-6), the basicity decreases and the mechanical properties of the weld metal deteriorate. If the amount is too large (B-7), cyander cuts with poor arc stability occur, and the bead shape becomes convex.

In B-8 and B-9, 102 is outside the specified range, and if it is insufficient (B-8), the arc safety will be poor and the beam will be uneven. If the amount is too large (B-9), cyander cuts with a convex slag shape with poor slag envelopment properties occur.

B-10, Bit is one in which sto□ is out of the specified range, and if it is insufficient (B-10), the slag tends to flow and the bead shape becomes convex. If the amount is too high (B-11), the viscosity of the slag becomes too high and workability deteriorates.

B-12 and B-13 have Mn and fluorosilicon mica outside the specified range, and B-12 lacks Mn, causing pits to occur due to insufficient deoxidation and poor arc stability. Furthermore, the bead shape, especially the bead toe, deteriorates due to the lack of silicon mica.

In B-13, when Mn is too large, the cracking resistance of the weld metal deteriorates and the amount of fume generation increases.

In addition, there is a large amount of fluorine-containing silicon mica, and the viscosity of the slag becomes too high, resulting in poor encapsulation properties.

In B-14 and B-15, the p'e powder and LiF were out of the specified range, and in B-14, the Fe powder was insufficient, making it impossible to obtain sufficient welding efficiency, and the arc stability was also poor. Sara K L
Due to the lack of iF, the coating material tends to absorb moisture and the amount of diffusible hydrogen increases. B-15 has too much Fe powder and the amount of slag is insufficient, resulting in a convex bead shape. Also, there is a lot of LIF, and the protective tube at the tip of the welding rod is broken, resulting in poor bead shape.

B-16, B-17 are 'pi, At, Mg,
Si.

If the SIC is outside the specified range and is insufficient (B-16
) causes pits. If it is too large (B-17), the stability of the arc will deteriorate and the amount of fume generated will increase.

E-18 If there is too much Cur Nl + Cr, Mo, the mechanical properties of the weld metal deteriorate and the amount of fume generation increases.

B-19 is a case where there are too many At203, and the isosceles becomes poor.

B-20 is a case where there is too much zr02, and the slag viscosity is too high and the beads become convex.

(Effects of the Invention) As described above, the welding rod of the present invention reduces the amount of fume generation without adversely affecting welding workability and bead shape, and has good pit resistance against Indian painted steel sheets. It has great practical value as a low-hydrogen coated arc welding rod for high-strength steel, and its contribution to improving the working environment is extremely significant.

Claims (2)

[Claims] (1) By weight, carbonate: 5 to 13%, however, MgCO3゜Total carbonate excluding Mn CO3 is 6 or less, metal fluoride: 1 to 9%, MgO: 6 to 18, TlO2: 15
~26%, SlO□near ~18%, Mn: 2~12%,
Fluorine tetrasilicon mica (KMg2,5(sto,.)F2
): ]~6chi, Fe powder: 15~50%, Ti, A
t, Mg, Si. Total of one or more types of SjC t-0.5 to 6%, LIF:
0.2-2.5% and Cu + Ni + Cr
A low hydrogen-based coated arc welding rod, which is made by adding a binder to a coating material containing 8% or less of one or more types of Mo and coating a carbon steel core wire. (2) In weight%, carbonate: 5 to 13%, but the total carbonate excluding MgCO3゜MnCO4 is 6- or less, metal fluoride: 1 to 9%, MgO: 6 to 18% 1T102
: 15-26 fy, 8102: 7-18 fy, M
n: 2-12%, n, tetrasilicon mica (KMg2
,5(sto,.)F'2): 1-6chi, Fe powder:
15-50 Chi, TI, At, Mg, SI. The total of one or more types of sic is 0.5 to 6 pieces, LIF:
0.2-2.5% and Cu + Ni r Cr +
Total f of one or more types of Mo: 8% or less, further KAt203
A low hydrogen-based coated arc welding rod in which a carbon steel core wire is coated by adding a binder to a coating material containing ZrOs: 6 or less and/or ZrOs: 1056 or less.