JPS6057434B2 - Low hydrogen coated arc welding rod - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a low-hydrogen coated arc welding rod that exhibits extremely good arc regeneration and welding workability.

Conventional CaCO3-CaF.

Low-hydrogen welding rods, which are mainly composed of Extra thick mild steel, medium carbon steel, free cutting steel and various high tensile strength steels equivalent to the standard, such as SM41B,
Widely used for welding SS5O, SM5, SB49, HW45, HW70 materials, etc.

By the way, it is well known that in general welding work, in addition to normal continuous joint welding, it is necessary to perform intermittent welding such as build-up welding, repair welding, and tack welding.

However, especially the above-mentioned CaCO. -CaF. In conventional low-hydrogen welding rods, the amalgamation of the coating remaining at the tip of the welding rod after the arc is extinguished is mainly non-conductive CaCO. Decomposition of CaO and further CaF. Alternatively, since it is composed of residual alkali silicate used as a binder, the conductivity of the sheathing tube becomes significantly poor, and as a result, when performing the above-mentioned intermittent welding, the tip of the sheathing tube needs to be touched only lightly to the object to be welded. The arc will not easily reoccur. Therefore, in order to regenerate the arc, it is necessary to forcefully press or strike the tip of the sheathed tube against the workpiece to break the sheathed tube and expose the welding rod core wire. in this case,
As the coating material that makes up the coating tube falls off irregularly, the core wire is exposed, and when re-welding, there is not enough coating material at the tip, resulting in insufficient encapsulation of gas and molten slag. , the directionality of the arc becomes irregular,
Since the welding atmosphere is disturbed, atmospheric oxygen and nitrogen enter the molten metal, causing significant defects such as bubble holes, pits, and slag entrainment, making it impossible to obtain a sound weld metal. Welding work was also difficult, as short circuits were likely to occur when rewelding was started. For welding rods whose core wires are coated with a coating agent containing a total of 50% or more of conductive iron powder and metal powder, the arc can be reactivated by simply touching the tip of the coating tube to the workpiece during rewelding. Occurrence becomes easier.

However, even in this case, the proportion of carbonates, fluorides, oxides, etc. that act as gas generating agents, slag generating agents, and arc stabilizers other than iron powder and metal powder decreases significantly, and their absolute amount decreases. Due to insufficient amount, proholes and bits are likely to occur in the weld metal, the shape of the bead waveform deteriorates significantly, and welding in vertical and upward positions becomes extremely difficult. Therefore, the arc can be easily regenerated, and
It has been extremely difficult to provide a low-hydrogen coated arc welding rod that has good welding workability in all vertical and upward positions. The present invention provides a completely new low-hydrogen coated arc welding rod that achieves both good arc regeneration and welding workability. One or more fluorides or complexes thereof 50-9
0%, and 10% to 50% of one or more types of metal carbonates around a flux-cored core wire filled with 2% to 20% of the weight of the carbon steel sheath with a filler containing 10% to 50% of one or more types of iron powder and metal powder. 4
5%, one or more metal fluorides 1-25%, one or more metal oxides 15% or less, iron powder 35-70%, metal powder 5-1
The present invention is a low hydrogen-based coated arc welding rod which is coated with a coating agent containing 8% by conventional means.

By configuring the low-hydrogen-based coated arc welding rod in this way according to the present invention, when the iron powder and metal powder contained in the filler and the iron powder and metal powder contained in the coating material are melted, the coating Is it possible to detect iron and metal powder remaining on the tip or inner surface of the cylinder during melting? However, since a slag with good electrical conductivity is formed, electricity can be applied simply by lightly touching the tip of the coated tube to the workpiece, making it extremely easy to generate an arc again.

On the other hand, in terms of welding workability, metal carbonates, fluorides, oxides, and their composites, which are enclosed as fillers in flux-cored core wires, replenish the lack of coating material around the core wires. Good welding workability can be obtained in all positions, and both excellent arc regeneration and welding workability are achieved. In addition, the metal carbonate mentioned here is Cac
O3, MgCO3, MgCO3・CaCO3, MnCO
3.BaCO3, Na2cO3, etc. are decomposed by welding heat and C
A substance that generates O2 gas.

Metal fluorides include CaF2, A'F3, BaF2, Mg
It refers to F2, NaF, Na3AeF6, MrlF2, KF, etc. Metal oxides include TiO2, SlO2, CaO
, MnO, MgO, FeO, A'203, Li20, B
a0, Na20, K20, TlO2●FeO, ZrO.
・SiO2, Na2O●Fe2O3●. 4S102,2
Ca0IMg0●2Si02, Ba0・Ae2O3・2
S102, Li20A'2032S102,4Ca0-
Ae2O3・Fe2O3, Al2O3・2s102・2
H20, 3r! 4g0-4si02・H2O-Na2O
・NslO2●XH2O, K2O-NsiO2・XH2
Refers to O etc. Metal powders include Mn, Si, Ti, Ni,
Single metal powder such as Gr, MO, V, Fe-Mn, Fe-
Iron alloy powder such as Si, Fe-A', Fe-Ti or A
'-Ti, Ae-Mg, Ca-Si, etc. alloy powder. The reasons for limiting the range of the filler to be enclosed in the core of the low-hydrogen coated arc welding rod of the present invention and the coating material to be coated around the core will be described below. First, 50% of one or more of metal carbonates, fluorides, oxides, or composites thereof are used as a filler to be filled into a carbon steel sheath as a flux-cored core wire.
The reason for setting it at ~90% is to replenish the gas generating agent, slag generating agent, and arc stabilizer that make the welding work good and protect the molten metal because the coating material around the core wire is insufficient. .

If it is less than 50%, the gas generating agent, slag generating agent and arc stabilizer will be insufficient, making it impossible to obtain a good bead and welding workability.

If it exceeds 90%, slag becomes excessive and the welding efficiency decreases; the reason why one or more of iron powder and metal powder is set at 10 to 50% is to improve arc regeneration, and if it is less than 10%, Arc regeneration becomes worse.

Furthermore, if there is not enough iron powder when enclosing a filler in a carbon steel sheath, the fluidity of the filler may be poor and the enclosing may become uneven. If it exceeds 50%, the amount of generated slag and gas will be insufficient, making it impossible to obtain good welding workability and bead shape.

The filling ratio of these fillers to the weight of the carbon steel sheath (filler weight/sheath weight x 100) was set at 2 to 20%.
If it is less than 20%, slag production and gas generating agent replenishment are insufficient, and if it exceeds 20%, the amount of slag becomes too large and the flux-cored core wire cannot be formed stably, resulting in a decrease in productivity. Another drawback is that the filler flows out or moves during transport of the welding rod or during welding. Next, one or more metal carbonates are added around the core wire as a coating component.
If it is less than %, there will be a shortage of gas, and proholes and bits will be more likely to occur.

If it exceeds 45%, the arc becomes unstable and the repeat shape becomes poor, and slag entrainment tends to occur.

If the content of one or more metal fluorides is less than 1%, proholes and bits are likely to occur in the slag. If it exceeds 25%, the formation of the sheathing tube will be incomplete, resulting in poor arc stability and short-circuiting during welding, as well as an increase in spatter or a marked deterioration in slag releasability.

The reason why 15% or less of one or more metal oxides is added is to improve arc stability, coated tube formation, or droplet transfer.If the amount exceeds 15%, the fluidity and viscosity of the slag will be inappropriate, and the slag will deteriorate. The encapsulability of the beads deteriorates, and the waveform and shape of the beads also deteriorate. Also, the slag peelability is poor,
Undercuts are also more likely to occur. Iron powder makes arc regeneration very good and is useful for improving welding efficiency. If it is less than 35%, arc re-occurrence will be poor, and if it is less than 70%
If the welding temperature is exceeded, the sheathed tube will not be formed and short circuits will easily occur during welding.

If the metal powder is less than 5%, the deoxidizing and denitrifying effects are insufficient and prohol is generated. If it exceeds 18%, deoxidation becomes excessive and the alloy components in the weld metal increase, resulting in the formation of bits in the bead and a marked decrease in the toughness of the weld metal.

The binder used here is an aqueous alkali silicate solution, such as sodium silicate, potassium silicate, or a combination of these.
The concentration and viscosity are adjusted and applied by appropriate means so as to obtain the best effect in terms of coating adhesion, productivity and welding workability. In addition, an alkali silicate component remains in the coating material, and the silicic acid component is used as a slag forming agent, and the alkali component is used as an arc stabilizer. The effects of the present invention will be shown below in more detail through Examples.

Example Table 1 is 4.0φ×400T! The flux-cored core wire formed into Un and the normal JISI class No. 1 core wire were each coated with a coating outer diameter of 6.3T$l by means of a public wholesaler, and then subjected to a drying and firing process. Regarding welding rods, SM4 corresponds to JIS and WES standards.
These are the results of detailed tests on arc re-occurrence and welding workability in each welding position of the welding rods of the present invention and comparative welding rods using IB, SM5OB, HW45, and HW7 products.

The criterion for determining whether arc re-occurrence is good or bad is plate thickness 12.7.
TIrm (7) SM4lB and HW45 with plate thickness 14wft
When performing straight rod operation with a welding current of 180 Amp by downward welding on a flat test plate, a depth of 15? Using a test plate machined with a V-groove with a groove angle of 600, vertical welding was performed with a welding current of 145 An1p, and after welding 100Tn and 20Tn from the tip of the welding rod, the welding was interrupted, and the coated cylinder was welded. After cooling to room temperature, rewelding was carried out, the coating tube was brought into light contact with the test plate, and the welding was repeated one pot at a time for each test plate, and it was considered good if the arc re-occurred within 3 seconds in all cases.

The criteria for determining whether welding workability is good or bad is SM4 with a plate thickness of 4h.
A test plate with a V-groove with a depth of 35 mm and a groove angle of 600 mm was used on the lB and HW4 bite plates, and a welding current of 1 was used for downward welding.
At 80Amp, upward welding and upward welding are 135A from the first layer to the second layer, and 145A from the third layer onwards.
When welding was carried out using a welding current of mp, the welding current was 140Amp and 160Amp when performing vertical advance welding on a test plate made of 14Tfn HW Senko plates combined in a T shape.
When performing single-layer fillet welding using Only cases where all of the items were excellent were considered good.

The results are as follows. First, symbols A-1 and A
-2 is a conventional rod using a normal JIS I Class No. 1 core wire, and arc re-generation and welding workability are not compatible with each other.

On the other hand, symbols B-1 to B-7 are welding rods composed of flux-cored core wire and coating material within the scope of the present invention, which are satisfactory because they have excellent arc regeneration and excellent welding workability. It is.

On the other hand, symbols C-1 to C-4 are comparison welding rods that use flux-cored core wires like the welding rods of the present invention, but since the filling rate, filler, or coating material is outside the scope of the present invention, the welding performance of each is evaluated. Not satisfied.

As explained above, the welding rod of the present invention makes it extremely easy to regenerate the arc, which was a problem with conventional low-hydrogen coated arc welding rods, and provides a coated arc welding rod that has excellent welding workability. It is.

Claims (1)

[Claims] 1. A filler containing 50 to 90% of one or more of metal carbon salts, fluorides, oxides, or composites thereof, and 10 to 50% of one or more of iron powder and metal powder in the carbon steel sheath. Around the flux-cored core filled with 2-20% of the weight, 10-45% of one or more metal carbon salts and 1 metal fluoride.
1 to 25% of more than one species, 1 to 25% of one or more metal oxides,
A low hydrogen-based coated arc welding rod coated with a coating material containing 35 to 70% iron powder and 5 to 18% metal powder by conventional means.