JPS59150694A - Low hydrogen coated arc welding electrode - Google Patents

Abstract

PURPOSE:To improve the cracking resistance and toughness of a weld metal, the efficiency and operability in welding operation and X-ray performance by using a sleeve packed specifically therein with metallic carbonate for a carbon steel core wire to be coated thereon with a covering material consisting essentially of metallic carbonate and metallic fluoride. CONSTITUTION:A carbon steel sleeve 1 which has no opening in its longitudinal direction and into which a packing material 2 contg. >=1 kind of metallic carbonate ore consisting of >=70wt% (hereinafter the same) of particles having 53- 500mu size is packed at 3-30% by weight of said sleeve is used as a core wire. A covering material contg. 7-60% >=1 kind of metallic carbonate ore, 3-28% >=1 kind of metallic fluoride, <=30% >=1 kind of metallic oxide, 4-24% metallic powder and, if necessary, <=40% iron powder is coated around such flux cored wire, by which a welding rod is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides low hydrogen-based coated arc welding using a flux input core wire that has extremely good crack resistance and toughness of the weld metal and welding workability, and greatly improves welding work efficiency. It's about sticks.

JISG35231m1 carbon steel core wire with OA・00
Conventional low-hydrogen coated arc welding rods coated with a coating material containing s -0aF2 t- as the main component are used in shipbuilding, machinery building, vehicles,
It is widely used in the field of welded structures, such as architecture, bridges, various pressure vessels, and offshore structures, where mechanical performance and crack resistance are particularly important.

However, in recent years, welding using the above-mentioned conventional low-hydrogen coated arc welding rod has been applied to mild steel plates with a tensile strength of 50 kg.
As high tensile strength steels with r/Wj or higher are increasingly used, cold cracking due to the amount of diffusible hydrogen in the weld metal often occurs, which has become a problem. This cold cracking can be prevented by preheating or postheating, but it is time consuming and inefficient, and fuel costs are high, making it uneconomical.

In addition, recently, offshore structures in particular are often used in cold regions, and requirements for toughness in addition to cracking resistance of weld metals have become higher.

Furthermore, conventional low-hydrogen coated arc welding rods have a slower melting rate (molten rod length per unit time) than non-low-hydrogen coated arc welding rods, and when used at high currents, the arc becomes rough and spatter is generated. High current weldability is poor, with increased scattering and poor slag removability. In addition, when welding with conventional low-hydrogen coated arc welding rods, blowholes and pits are likely to occur at the starting end of the weld bead or at the seam. The method involves coating the core with a hole, or drilling a hole at the tip of the core wire, or both, and using the Nosex Tezzo method. However, even if the noise prevention means described above are used, it is still not always satisfactory in terms of welding efficiency, welding workability, and X-ray performance, and it is also not satisfactory in terms of economy due to the increase in man-hours in the welding rod manufacturing process. There wasn't.

Therefore, there is a strong demand from the industry for the development of a low-hydrogen coated arc welding rod that has excellent weld metal cracking resistance and mechanical performance, as well as ease of use and efficiency in welding work.

In order to meet the above-mentioned needs, the present invention has been developed as a result of various studies on low-hydrogen-based coated arc welding rods from both the core type and coating material, and has been developed to improve cracking resistance and toughness of weld metal, welding work efficiency, This is a low-hydrogen coated arc welding rod that has greatly improved welding workability and X-ray performance.

53-50 in a carbon steel shoe with no longitudinal openings.
A flux-cored core wire is filled with a filler containing at least 70% of metal carbonate minerals with a diameter of 0 μm at 3 to 30% based on the weight of the carbon steel sheath. 7-60% of one or more types.

A low-hydrogen coated arc welding rod fully coated with a coating containing 3 to 28% of one or more metal fluorides, 30% or less of one or more metal oxides, and 4 to 24% of metal powder, and the above coating. A low hydrogen-based coated arc welding rod is coated with a coating material that further contains iron powder in an amount of 40% or less.

Incidentally, in this specification, ``chi'' means % weight.

The low hydrogen-based coated arc welding rod of the present invention has the advantage that when the metal carbonate mineral sealed as a filler and the coating mineral are melted,
Excellent arc conditions and molten slag formation result in finer molten metal particles, smoother droplet transfer, stable arc, less spatter, and significantly improved welding workability and efficiency. On the other hand, when the metal carbonate mineral added to the inside and outside of the core wire melts, the CO2 gas decomposed becomes a gas flow from the inside and outside of the welding rod, forming a good arc atmosphere. By preventing the intrusion of N2, an excellent weld metal with a drastically reduced amount of I]2 + 02 a NZ can be obtained. This improves the cracking resistance and toughness of the weld metal. Furthermore, since the current density relative to the cross-sectional area of the core wire is increased, no blowholes or pits are generated at the beginning of the welding beat or at the joint, and the X-ray performance is significantly improved.

That is, the welding rod of the present invention uses a flux-cored core filled with a gas generating agent in combination with a coating material containing metal carbonate minerals, metal fluorides, metal oxides, metal powder, iron powder, etc. This is an innovative low-hydrogen coated arc welding rod that has excellent welding workability and efficiency, as well as good cracking resistance and toughness of the weld metal, as well as good X-ray performance.

In addition, the metal carbonate mineral in the present invention is Oa.003
, Mg003.0aOO17Mg00g , Mn0
03, Ba003°N a2003, K2003
Metal fluorides are substances that decompose with welding heat and generate OOz gas.

, BaFl, MgFl, NaF, KF, MnF, Na5
AtF6, etc., and the metal oxide is T + 02,
S i OH, Oa O, M n O.

MgO, FeO, Fe203, LilO,
BaO, Na2O, K! 0 and TiO2* of these compounds
FeO, ZrO2', "5i02, 20aO" Mg0a
28402, BaO*A4203 ・20aO, Na
ff1O*n5ioz*xH2O, etc., and the metal powder is Mn, 81. Ti, Ni.

Single metal powder such as Or, Mo, V, Fe-Mn, Fe-
81° Iron alloy powder such as Fe-AL, Fe-Ti, Fe-Mn or pLt-Ti, AL-Mg, 0a-8t,
81-Mn, etc.

Hereinafter, each requirement of the present invention will be explained in detail.

In the low-hydrogen coated arc welding rod of the present invention, the use of a carbon steel sheath 1 having no openings in the longitudinal direction as a flux-cored core as shown in FIG. 1 improves the concentration and directivity of the arc. This is to stabilize the filling flux 2 and to prevent the filling flux 2 from absorbing moisture and from expanding and flowing out during welding. Furthermore, the purpose is to improve the forming processability of the core wire and the wire feedability during production of the welding rod, so that the welding rod can be manufactured efficiently and economically.

The basic test results shown in Table 1 show that the reason why the carbon steel sheath, which has no openings in the length direction, is filled with metal carbonate mineral particles with a diameter of 53 to 500 μm is 70% or more. This is because it is known that it can be filled uniformly and efficiently, and that very excellent effects can be obtained on the forming processability during drawing and cutting of the 7 lux input core wire. That is, Table 1 shows carbonate lime as fine particles with a diameter of 52 μm or less, 53
~Book 250-N11 467- Classified into 4 types, each particle size range is individually or mixed in an appropriate ratio, and outer diameter 6 with various wall thicknesses are prepared.
This shows the results of a comprehensive investigation of the filling properties and formability of flux-cored core wires when filling a carbon steel shaft with no openings in the longitudinal direction of ~2h-, taking into account the filling rate. According to the same table, the particle size of the filler is 53 to 500.
This is because it is known that when the micrometer is 70 inches or more, both filling properties and moldability are excellent.

Filling with one or more types of metal carbonate minerals is because the filled metal carbonate minerals decompose during welding and generate 00□ gas from the inside, which creates an excellent gas flow in the arc atmosphere and prevents droplets from forming. This is because the transition is completely smooth, the arc is completely stable, the molten metal is sufficiently shielded, and the performance of the weld metal is improved.

The filling ratio of the filler to the amount of carbon steel sheath mold (filler weight/carbon steel sheath mold amount 59-150
894 (5) is insufficiently effective, and if it exceeds 30%, engraving cannot be performed stably and productivity will decrease, and the filler will easily flow out during welding, making the performance of the weld metal unstable. This is because it becomes.

Next, the reason why one or more types of metal carbonate minerals are set to 7 to 60 degrees as a coating material component to be coated around the core wire is that if it is less than 796 degrees, there will be insufficient shielding gas, blowholes and bits will be generated, and the weld metal will be damaged. This is because if the amount of diffusible hydrogen increases and exceeds 60 inches, the arc becomes unstable, the bead shape becomes poor, and slag entrainment tends to occur.

The reason why one or more metal fluorides is set to 3 to 28 thick is that if it is less than 3 thick, the slag will lack viscosity and the encapsulation will deteriorate, and the bead shape will deteriorate and blowholes and bits will easily occur. If it exceeds 28 degrees, the melting point of the coating material will be too low and the coating tube will not be formed completely, the arc will be unstable and short-circuited during welding, spatter will increase, and the slag removability will deteriorate significantly. Because it does.

The reason why the content of one or more metal oxides is 3 (L or less) is to improve the stability of the arc and the formation of a coated tube or the transfer of droplets. This is because the encapsulation of the slag is poor (f), and the blowing properties of the arc become too strong, making it easy for molten metal to drip during vertical and upward welding.

The reason for setting the metal powder to 4 to 24 inches is that if it is less than 4 inches, the deoxidation and denitrification effects will be insufficient and blowholes will occur, and if it exceeds 24 inches, the deoxidation will be excessive and bits will occur in the weld bead. This is because the toughness of the weld metal decreases significantly.

The reason why less than 40% of iron powder is added is because it is useful for improving the efficiency of welding work, and because if it exceeds 40%, the sheathing tube becomes too shallow and short-circuiting occurs easily during welding.

The effects of the present invention will be specifically illustrated by comparing the welding rod of the present invention, a comparative welding rod, and a conventional welding rod.

Table 2 shows the filler percentage, the filler percentage, and the coating material percentage of the welding rod of the present invention, the comparative welding rod, and the conventional welding rod. Note that consideration was given to ensuring that the particle size of the filler was 53 to 500 μm and was 70 cm or more.

Table 3 shows the performance test results of the welding rod of the present invention, the comparative welding rod, and the conventional welding rod.

That is, 4.0 m x 450 + mn of flux-cored core wires filled with the filler shown in Table 2 at a predetermined filling rate are placed in carbon steel shafts with various wall thicknesses, outer diameters of 20 mm, and no openings.
Cord wire molded into or regular JIS G35231
A coating agent is applied to the type 1 core wire by a known method until the outer diameter of the coating is 6.
Each coated material was coated so as to have a thickness of 3.3 mm, and then a welding rod was created using the gold diameter through a drying and firing process. These welding rods of the present invention, comparative welding rods, and conventional welding rods: 1) Welding workability and welding work efficiency using 5U-4tn and 5M-50B corresponding to JIS standards and HW50 materials corresponding to WE8 standards. The crack resistance, toughness, and X-ray performance of weld metal were tested and determined in detail.

The criteria for determining whether welding workability is good or bad is by using a test plate with a 5M-41B and HW50 steel plate with a thickness of 251H and a V-groove with a depth of 20mm and a groove angle of 60°. When welding is carried out at a welding current of 180 Amp, and welding is carried out at a welding current of 130 to 160 Amp for vertical advancement and upward welding, welding is performed using a test plate made of 14 m thick 5M-41B steel plates combined in a T shape. Stability of each arc when performing horizontal fillet welding with a current of 180 Amp1. Tests were conducted for slag fluidity, releasability, bead appearance, and the presence or absence of bits at bead joints.5 If all of these test items were excellent, it was considered to be completely good.

The criteria for determining whether welding work efficiency is good or bad is a welding current of 18 Q A when downward welding on a 5M-41B steel plate with a thickness of 14 W.
The length of the molten rod per unit time was measured when the rod was operated straight with MP and welded 5 times, and cases where the average value of the melting rate was 2901 mm or more were considered good.

The criteria for determining whether the cracking resistance of weld metal is good or bad is plate thickness 2.
J I 8 Z3157 using HW 50 steel plate.
According to the U type # contact cracking test method, welding current 1 at room temperature
A cracking test was conducted at 80A and a welding speed of 150 gourds/min.
A case in which root cracking did not occur three times was considered good.

The criteria for determining whether the weld metal has good or bad toughness is a plate thickness of 25 m.
Using 5M-50B steel plate of
Based on the Z2242 test method, each welding position is 140
Tested 5 pieces each at ℃, all of them were 4.8k
A case where a value of g·m or more was shown was considered good.

The criteria for determining whether the X-ray performance is good or bad is plate thickness 25tr/)
S M -50B steel plate with a depth of 20mm and a bevel angle of 60°
The downward welding using the test sheet metal processed with V clear sound is 180A.
mp, vertical and upward bath welding, welding current of L 50 Amp, puncture step operation was not performed, and 10 test specimens were repeatedly prepared for both the weld bead start end and bead seam weld pitch position JIS Z3104. The test was conducted according to the X1M test method, and if the test result was 1st class or higher in both cases, it was considered good.

In Table 3, symbols B-1 to B-3 are the conventional JI
This is a case of welding with a conventional welding rod using SG 3523.1 type 1 core wire, and the toughness is particularly low, and the frequency of occurrence of blowholes at the weld joint is significant, and various welding performances are not satisfied.

Next, symbols 0-1 to 0-10 indicate cases of welding using a welding rod composed of a flux-coated core wire and a coating material according to the present invention, which are excellent in ease of welding in each position, efficient and efficient welding. It fully satisfies the various performances required for metals.

Symbols D-1 to D-5 are cases of welding with a comparison welding rod using a 7-lux core wire similar to the welding rod of the present invention.

The coating compositions of the welding rods D-1 and D-5 are both within the scope of the present invention, but the filling rate is outside the scope of the present invention. First, symbol D-1 has a too low filling rate, so when welding,
The amount of gas generated from the inside of the core wire is insufficient, resulting in poor welding workability, and welding work efficiency has not improved. -10,000 symbol D-
In No. 5, the filling rate is too high, and the amount of gas generated is excessive, making it impossible to obtain stable welding workability and the toughness of the weld metal.

Although the filling factors of the welding rods with symbols D-2, D-3, and D-4 are within the range of the present invention, the composition ratio of the coating composition is outside the range of the present invention. First, in the case of symbol D-2, the metal carbonate mineral and metal powder exceed the upper limit of the present invention, and the metal fluoride content is less than the lower limit of the present invention, so welding workability, weld metal toughness, and X-ray performance are inferior. Next, symbol D-3 has metal carbonate minerals less than the lower limit of the present invention and metal fluorides and metal oxides exceeding the upper limits of the present invention, so welding workability, crackability of weld metal, and X-ray performance are poor. Inferior. Furthermore, in symbol D-4, the iron powder exceeds the upper limit of the present invention and the metal powder is less than the lower limit of the present invention, so welding workability, crackability and toughness of weld metal, and X-ray performance are inferior, and the welding performance is not fully satisfied. .

As explained above, according to the welding rod of the present invention, the following effects can be obtained.

Table 3 Judgment criteria: ○Good, ×Poor 1

[Brief explanation of drawings]

FIG. 1 shows a flux-cored core wire used in the welding rod of the present invention. 1 indicates a carbon phase, and 2 indicates a filler gold. Agent: Patent attorney Masaaki Akisawa 2 people outside the party 2

Claims (2)

[Claims] (1) In a carbon steel shoe with no openings in the length direction, 53
A filler containing one or more metal carbonate minerals having 70 or more particles with a diameter of ~500 μm is added to the amount of the carbon steel sheath mold at a rate of 3~50 μm.
Around the flux-cored core wire filled with 3096, 7 to 60% of one or more metal carbonate minerals, 3 to 28% of one or more metal fluorides, 30% or less of one or more metal oxides,
4 to 24% of metal powder, fully coated with a coating material containing ';
A low hydrogen-based coated arc welding rod. (2) In a carbon steel shoe with no opening in the length direction, 53
A filler containing one or more metal carbonate minerals containing 70% or more of particles with a diameter of ~500 μm is added to the amount of the carbon steel sheath mold from 3 to
Around the 7 lux core wire filled with 30eI6, 7-60% of one or more metal carbonates, 3-28% of one or more metal fluorides, and 30% or less of one or more metal oxides. ,
A low hydrogen-based coated arc welding rod characterized by being coated with a coating material containing 4 to 24 inches of metal powder and 40 inches or less of iron powder.