JPS58148096A - Production of packing wire for welding - Google Patents

Abstract

PURPOSE:To reduce the content of N2 in weld metal and to obtain the weld metal having good performance in the production of a packing wire wherein a steel pipe is used, by substituting and removing the air in the air-gap in the pipe after the pipe is packed with a flux with a gas contg. no N2. CONSTITUTION:A vacuum pump (d) and a gas bomb (e) for Ar, CO2, etc. are mounted at both ends of a steel pipe F wound like a coil H after the packing of a flux therein is finished. The operator closes a cock f2 and evacuates the inside of the pipe F. After checking the degree of vacuum with a manometer h2, the operator closes a cock f1, stops the pump (d), and starts supplying of gas from the bomb (e) by closing and opening the cocks j2, f2. The operator recognizes the progression of the substitution with the gas from the rise of the internal pressure indicated by a manometer h1 in this stage and when the pressure rises to 1atm or above, the operatore closes and opens the cocks f2, j2 and after a while, he checks the correct internal pressure of the pipe with the manometers h1, h2. After the checking, the operator removes tubes A, B, and seals the pipe F quickly to prevent the intrusion of the air from the end part.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention solves the problem of welding, especially when welding high-tensile steel and low-temperature steel using a flux-cored filler wire (hereinafter referred to as seamless filler wire) made of steel pipes. This invention relates to a method for manufacturing a filling wire for welding developed for the purpose of reducing the amount of N2 in metal.

Seamless filling wire is filled with 7 lux composition (alloy agent, deoxidizing agent, slag forming agent, gas generating agent, other F/powder, etc.)
Since it can be freely changed, it is easy to create a wire with an alloy composition that is suitable for welding various copper plates, and it also provides better welding workability and superior weld metal performance than when using solid wire. That's what you get. Furthermore, by using steel pipes, the wire surface can be subjected to copper plating or wet treatment for cleaning, which was not possible with conventional folding type filling wires (cheapler wires) made of steel strips. In addition, the flux filled in the pipe is completely isolated from the outside air, so it will not be affected by the outside air* (a, O moisture absorption, etc.) even during the reed manufacturing stage and during long-term storage after manufacturing. It is expected that its use will expand in the future in Japan as a wire for various welding applications, including wires for submerged arc welding and gas-shielded arc welding.

The advantage of the traditional seamless filling wire manufacturing method is powder t
Alternatively, after filling a large-diameter medium-sized steel pipe with 7Lux, which has been granulated by water glass mixing, with the main purpose of preventing segregation of the filling flux composition and adjusting the filling rate (adjusting the bulk density of the filled 7Lux), The diameter of the wire is gradually reduced by turning the wire to a predetermined welding wire diameter (1.2 mφ to 6.4 mmφ), but the work hardening of the steel pipe occurs immediately after filling, at the same time, and at an intermediate stage of diameter reduction. In some cases, SR treatment is performed one or more times, and surface treatments such as pickling and copper plating are performed in order to ease the stress and make wire drawing easier. In addition, the above-mentioned 8R treatment, which is carried out at high temperature for the purpose of softening the steel pipe, leaves 9H in the 7L, especially when it is filled with flux granulated with water glass.
It has been confirmed by the diffusible hydrogen test of weld metal that it is also very effective in removing 20.

By the way, when welding is carried out using a nine-seamless filled wire manufactured by such a conventional method, the amount of N2 in the welded metal at 1W is essentially the same level as when using a solid wire with the same alloy composition system. However, problems such as deterioration of the toughness of the weld metal occur, especially when welding high-strength steel or low-temperature steel.

The present inventors have developed a filling hook composition with the aim of reducing the amount of N2 in the weld metal to the same level or lower than that when using a solid wire even when a seamlessly filled wire is used for welding. In addition to the study, various manufacturing methods were investigated.

In the filling flux composition, the selection of raw materials (especially alloying agents) taking into account the nitride content and the selection of gas generating agents (CaC01
It was found that addition of carbonates such as carbonates) was effective, but the effect was still insufficient. Therefore, we came to the conclusion that the increase in the amount of N2 in the weld metal was mostly due to the air packed into the steel pipe along with 7 lux during filling, and we decided to consider how to remove the air in the pipe in relation to the amount of N2 in the weld metal. As a result of various attempts, we discovered a simpler and more efficient method for removing air, and by adding the step of removing air to the conventional seamless filling wire manufacturing method, we were able to reduce the amount of N. This made it possible to obtain a weld metal with good performance.

That is, the present invention is characterized in that in manufacturing a filled wire using a steel pipe, after filling with flux, vacuum suction is performed, and then any gas that does not contain nitrogen is introduced to replace the gas and remove air remaining in the void inside the pipe. This is a method of manufacturing a filling wire for welding.

The present invention will be explained in detail below.

Figure 1 shows the cross-sectional structure of a steel pipe immediately after filling, which has not yet been subjected to drawing or SR treatment.
When the flux particles C, the pipe wall b', the filling flux O, and especially the filling flux are granulated and crushed, a void 1 is created in each flux particle C, and in these minute spaces, air is almost 1 It is thought that it remains in an i state near atmospheric pressure. In addition, charging of 7 lux is carried out by placing a coiled steel pipe on a table to which rotational vibration is applied, and sequentially supplying 7 lac from one end that is pulled upward.

Next, FIG. 2 is a schematic diagram showing one embodiment of the method of the present invention. As shown in the figure, after filling is completed, a vacuum pump d and a gas generator are connected to both ends of the steel pipe y wound into a coil H shape. Attach the chip pipes A and B containing the cock fl*fl and the glass fiber filter g, which are directly connected to the . In the same figure, hl and li are manometers C for measuring the pressure inside the tube, and js and Js are cocks for measurement, respectively.

As a procedure for carrying out the method of the present invention, first, cook f.

Close the tube and perform vacuum suction inside the tube. The degree of vacuum should be determined using a manometer, but it may be up to about 10 atmospheres. Next, close cock fl, stop the vacuum pump, and cock j! Close the cock f! When opened, gas starts flowing from the gas tank. At this time, the internal pressure indicated by the manometer h gradually increases, indicating that replacement (filling with gas) by the inflowing gas is progressing. When the i meter HL reaches 1 atm or more, close the cock f3 and stop the gas inflow.
After opening the cock j3 for a while, check the pressure inside the pipe more accurately by reading 1+h1 on the manometer. It is necessary to continue the gas inflow until the pipe internal pressure finally reaches 1 atmosphere or more. After the pressure clearly reaches 1 atmosphere or more, remove the cheap tubes A and B attached to both end ports and promptly seal them to prevent air from entering the ends.

Note that after vacuum suction inside the tube, it is possible to replace the gas by flowing in gas while continuing vacuum suction, by adjusting the opening and closing of cocks f and f, but this can be done without wasting gas. consumption. It is also possible to carry out the present invention after evacuating the inside of the tube before filling, or after replacing the gas, and then carrying out the present invention, but this is not an efficient method since the air is drawn in with the flux again during filling. I can't say that there is.

Note that any gas that does not contain nitrogen used in the present invention means any gas that can remove or replace air, and that does not cause performance deterioration of the weld metal when welding is carried out in the built-in gas. and mixed gases thereof. Ar*CO2 gas is particularly effective, but N
2*H., O2 gas, etc. can also satisfactorily achieve the purpose depending on the filling flux composition or the manufacturing process.

In addition, it was observed that at the beginning of diameter reduction, the extension in the longitudinal direction of the steel pipe was relatively small compared to the later stage, and the internal volume of the pipe decreased rapidly, that is, the internal 7 lux became compressed. be done. At this time, the gap in which the air remains is naturally narrowed.

As diameter reduction progresses further, the air gap will become narrower and the pressure of the trapped air will gradually increase, but on the other hand, the 7 lux inside the pipe will become tightly packed, so the total length of the steel pipe at the manufacturing stage will be reduced. Therefore, it is impossible for air to escape outside the tube except in a very small portion near the ports at both ends. Furthermore, even in the portions near both ends, air equivalent to 1 atm cannot escape.

Because the steel pipe is used for the air remaining in the pipe when filling the pick, there is no escape port, and the pressure gradually increases, and almost all of the air remains in the pipe.When welding is performed, N2, the main component of the air, is released into the molten pool. As a result, the amount of N2 in the weld metal increases, causing deterioration of toughness.

From the above, in order to reduce the amount of N2 in the weld metal, it is necessary to remove the air remaining in the pipe. It can be seen that it is more appropriate to do this immediately after filling, even after it becomes difficult to move.

It should be noted that it is possible to remove air remaining in the pipe after a slight diameter reduction or after performing SR treatment after filling, but before starting diameter reduction, although there are some problems in terms of efficiency and convenience. It is.

Further, as an additional effect of the present invention, it is recognized that the amount of diffusible hydrogen in the weld metal is slightly reduced.

This is due to the N20 in the air due to vacuum suction.
This is considered to be the result of the removal of N20 adhering to the 7 lux grains and the inner wall of the steel pipe before filling, since the saturated steam pressure is significantly lowered due to the lowering of the pipe internal pressure.

The effects of the present invention will be illustrated in more detail below with reference to Examples.

Example WJ1 Filled with 7 lux (granulated flux, particle size 12 mesh or less) having the composition shown in Table WJ1, an outer diameter of 12 mm and an inner diameter of 8 mm.
Seamless filling wire by the method of the present invention was filled into a steel pipe, and after filling, the air remaining in the pipe was removed as shown in Fig. 2, and the diameter was reduced. Seamless filling wires (wire diameters of 4.0 mφ each) were manufactured as prototypes, each weighing approximately 400 kg, using a conventional method. At this time, in the case of the method of the present invention, the degree of vacuum inside the tube is approximately 10 atm (suction time,
Although high-purity Ar gas was used as the replacement gas after suction, the internal pressure of the pipe after replacement was 1.2 atm. All of the seamless wires mentioned above were subjected to one SR treatment at an intermediate stage of diameter reduction, and the wire surface was plated with copper.

Table 1 Filling flux composition (heavy lid skin) 1) Others, such as 20%, SiQ□, unavoidable impurities, etc. After welding, we made a seamless filling wire and welded a solid wire (wire diameter 4.0
■φ) is combined with a highly basic fusion type welding flux to produce a 3.5% Ni steel (ASTM, A203) with a plate thickness of 25 haze.
GrE) with V groove, groove angle 30', root spacing 12.
5. A groove with a backing metal was used, and multilayer welding (Sazomano arc welding) of one layer and two base metals was performed. Welding conditions are AC
Power supply, 500Amp, 30Volt, 37m/
mln, preheating, and interpass temperature of 150'C.

In addition, when using solid wire, the voltage is 28 Vol.
The test was carried out under the same conditions as the metal ring. A JIS No. 4 2V notch Charpy impact test piece having a notch position (C) or (D) as shown in FIG. 3 was taken from the center of the weld metal obtained and subjected to the test. In the figure, 1 is a fine grain part, 2d is a coarse grain part, 3 is a weld heat affected zone, and 4 is a base material to be welded. Table 2 summarizes these results.

Table 2 Welding performance test results Test section 1 using wire manufactured by the method of the present invention was welded using wire manufactured by the conventional method (N12)
Compared to this, the N2 content of the weld metal is clearly reduced and the impact value is also improved. It also shows a slightly higher impact value compared to N113 using solid wire, but this is due to the weld metal's zero impact value due to CaF2 in the filling flux composition.
This is considered to be a 9 effect, with a decrease in the amount of 2. Note that welding workability was good for all of N1L1-3 without any problems.

As described above, the present invention is a method for manufacturing high-quality filled wire that for the first time makes it possible to reduce the amount of N2 in the weld metal, which is a problem when welding is performed using seamless filled wire.] Industrial Practical The quality is extremely high.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the cross-sectional structure of a wire immediately after being filled with flux, FIG. 2 is a schematic diagram showing one embodiment of the method of the present invention, and FIG. 3 is a diagram showing the sampling position of an impact test piece. a...Gap in the steel pipe b...Steel! b'...tube wall @, e'...7 lux grains d.
・・Vacuum・・・・Gas is pumped f,, fs
and b*Jm-cock g...filter
h,,h,...manometer F...steel pipe
H...Coil (C) and (D)...Notch position of impact test piece 119. Fine grain part 2...
・Coarse grain part 3...Welding heat affected zone 4...Base material to be welded. ri;・i [11 Figure 3

Claims (1)

[Claims] Filling for welding, in the production of a filling wire using a steel pipe, after filling with flux, vacuum suction is performed, and then any gas that does not contain nitrogen is introduced to replace the gas, and air remaining in the void inside the pipe is removed. Method of manufacturing wire.