JPS6130286A - Gas shielded arc welding method and composition for preventing blowhole for welding - Google Patents

Abstract

PURPOSE:To prevent the generation of blowholes by spraying specifically composed powder at a specific ratio along a weld line prior to welding. CONSTITUTION:At least one kind of a powder group consisting of TiO2, ferrotitanium, ferromanganese, ferrosilicon, iron, ilmenite, aluminum, SiO2, mica, talc and potashfeldspar is sprayed at 1-50g ratio for each 1m prior along the weld line to gas shielded arc welding. The spraying of the powder is thus made possible by the simple operation of sliding merely the compsn. over the weld zone, by which the generation of blowholes is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to a gas-shielded arc welding method and a welding blowhole prevention composition used in carrying out the method.

(Prior art) When performing gas-shielded arc welding using composite wire or solid wire, if the welded area is coated with a primer2 or if there is rust or oil adhesion along with this coating, it may be necessary to leave it as is. If welding is done in such a condition, there is a high probability that a blowhole will occur. In particular, when a composite wire is used, the internal flux collects moisture in the air from the inclusion gap on the wire surface due to oral change, and blowholes are more likely to occur than when a solid wire is used.

If a blowhole like the one described above occurs, it will lead to a decrease in the strength of the joint, and it will take a lot of work to repair it, so conventionally, the welded part was heated with a gas burner before welding. Preparatory work includes removing moisture and grease by preheating, wiping the weld with an organic solvent such as acetone to remove grease, and removing primer and rust with a grinder.

(Problems to be Solved by the Invention) However, the preparatory work such as preheating with a burner, degreasing with an organic solvent, and grinding with a grinder as described above usually requires a great deal of effort, which reduces the efficiency of welding work. It is the cause of the invitation.

This invention was made to solve the above-mentioned conventional drawbacks, and its purpose is to prevent blowholes from occurring with a simple operation even when there is primer coating, oil, fat, moisture, etc. in the welded part. The object of the present invention is to provide a gas-shielded arc welding method that can improve welding efficiency and a blowhole prevention composition for welding that is suitable for carrying out this method.

(Means for Solving the Problems) Therefore, in the gas shielded arc welding method of the present invention, TiO2, ferrotitanium, ferromanganese, ferrosilicon, iron, illuminite, aluminum, SiO2, mica, talc, At least one type of powder group consisting of potassium feldspar is applied along the weld line at a rate of 1 per meter.
It is recommended to spray at a rate of ~50g.

The welding blowhole prevention composition suitable for carrying out the above method is a powder group consisting of TiO2, ferrotitanium, ferromanganese, ferrosilicon, iron, illuminite, aluminum, 5in2, mica, talc, and potassium feldspar. (1 type, sodium silicate, lithium silicate,
It is made by kneading with an aqueous solution of at least one type of silicate group consisting of potassium silicate, molding, and drying.

(Effect) It is not theoretically clear why blowholes can be prevented when the above powder is spread along the weld line, but based on the observation results of the molten pool during welding, the following It is estimated that In other words, a violent boiling phenomenon is observed in the molten pool immediately after passing through the welding arc, but this is because the slag component is separated from the molten metal and floats to the surface. It is thought that this stirring action causes the gas that causes blowholes to float together with the slag before the molten pool solidifies, thereby preventing the occurrence of blowholes.

Further, when ferromanganese, ferrosilicon, iron, aluminum, etc. are used and carbon dioxide gas is used as the shielding gas, the following blowhole prevention mechanism can be considered. That is, each of the above powders combines with oxygen dissociated from carbon dioxide gas by arc heat, becomes a slag forming agent of each oxide, generates heat, and floats up while stirring the molten pool, and at this time blows. This is a phenomenon in which hole-generated gas is dissipated from the molten metal.

However, when using each of the above powders to weld a welded part with oil or fat attached, that is, where the gas that is the main cause of blowholes is hydrogen rather than oxygen as mentioned above, blowballs may still occur. Although it is possible to prevent the occurrence, in this case, it is presumed that only the above-mentioned stirring phenomenon occurs, rather than the above-mentioned oxidation phenomenon.

When ferrotitanium is used, in addition to the above-mentioned stirring phenomenon, it can also have the effect of fixing nitrogen, which is usually the main cause of blowholes.

Furthermore, when using the blowhole prevention composition for welding as described above, each powder can be spread by simply sliding the composition over the welding area.
It's extremely convenient.

(Example) Next, a specific example of the gas-shielded arc welding method of the present invention will be described together with a welding blowhole prevention composition used for its implementation.

It's a practical plate.

When welding the T-shaped fillet of a 12 mm thick zinc clinch primer coated steel plate (film thickness 10 microns), weld the fillet on the back side of the welding side in advance to prevent gas from escaping. Next, beef tallow was infiltrated along the weld line at a rate of 4 cc per meter to forcibly create an oil stain.

Using this forcibly oil-stained steel plate coated with a zinc clinch primer, horizontal fillet welding was performed using a composite wire (As-1 manufactured by Sumikin Welding Co., Ltd.) having a diameter of 1.2 fl. The welding conditions were: welding current 25OA, welding voltage 30V, DC reverse polarity, welding speed 30cm/min, CO, flow rate 2QA/min.
min, but the number of blowholes generated in this case was 40 per 1 m.

Next, under the same conditions as above, a T
iO2 powder was spread at a rate of 8 g/m and welding was carried out under the same conditions, but no blowholes occurred in this case.

Furthermore, experiments were conducted under the same conditions for AI, Fe-Ti, and illuminite to examine their blowhole prevention effects.

These results are summarized in Table 1.

Table 1 ◎・・・Bead appearance is very good △... Slightly bad ×・・・　〃〃　Very bad Really what (.

10 parts of a water glass solution consisting of 5 parts of a sodium silicate aqueous solution having a specific gravity of 38° and 50 parts of water was added to a mixture of 50 parts of Fi-Ti powder and 50 parts of TiO2 powder and kneaded. Next, this was put into a round bar-shaped mold with a diameter of Ion and a length of 10 cm and molded, and then dried at 120° C. for 2 hours to create a chalk-like round bar.

Similar to the case of T-type fillet welding of the zinc-rich primer coated steel plate in the AS-1 composite wire with a diameter of 1.2n described above, fillet welding was performed on the back side of the weld in advance to prevent gas from escaping. Next, an 80% trimethylolmelamine aqueous solution (a strong N2 generating source) was uniformly infiltrated into the welding line at a rate of 2 cc/m using a glass syringe. The above-mentioned chalk hardened with water glass was rubbed along the welding line to adhere the chalk to 2 g/m. In this case, no blowholes were generated during welding under the same conditions as in Example 1. In addition, when the same chalk was not attached, blowholes were generated at a rate of 20 pieces/m.

S】H discharge■・ 1/7 amount of ferrosilicon, 17 amounts of Fe lees powder, 1/7 amount of ferromanganese, 1/7 amount of SiO2, 1/7 amount of mica, 1/7 amount of talc, 1/7 amount of potassium feldspar, The seven isostat compounds were kneaded with a mixed aqueous solution of lithium silicate and potassium silicate, then formed into a round bar with a diameter of 101 m, and dried at 140°C for 1 hour. Using an oil-stained primer steel plate under the same conditions as in Example 1, and under the same conditions as in Example 1, an AS-1 diameter of 1.
Horizontal fillet welding was performed using 2fi wire. No blowholes were observed in the case where the round rod was applied to the weld line at a rate of 5 g/m before welding.

1. Horizontal fillet welding of the CO2 shield was performed using solid wire SCT for carbon dioxide arc welding, diameter IJmm, manufactured by Sumikin Welding Industry ■. Welding conditions are 30VX26OA, Co
2-Flow rate 2Qj! /min, welding speed 30m/min
.

A plate coated with a zinc-rich primer (film thickness 10 μm) and having a thickness of 1211 m was used. Before performing T-shaped horizontal fillet welding, fillet welding was performed on the back side of the welded part in advance to block the passage of gas escaping to the back side during actual welding.

Mineral oil-based machine oil was injected into the weld line at a rate of 5 cc/m.

Next, an equal compound of TiO2 and ferromanganese was sprinkled on the oil-applied weld line at a rate of 50 g and 7 m, and then horizontal fillet welding was performed under the same conditions as above. As a result, when only oil was applied, three blowholes were generated, whereas when TiO□ and ferromanganese were used, no blowholes were generated.

In addition, as a method of distributing each powder to the welding part, a spray method is used, that is, liquid Freon gas, various powders,
Using a method in which a dispersant etc. is sealed and sprayed from a nozzle,
We have conducted tests similar to those above and confirmed that the same effects as above can be obtained.

Claims (1)

[Claims] 1. Before welding, at least one of the powder group consisting of TiO_2, ferrotitanium, ferromanganese, ferrosilicon, iron, illuminite, aluminum, SiO_2, mica, talc, and potassium feldspar is added to the welding line. A gas-shielded arc welding method characterized in that the gas is applied at a rate of 1 to 50 g per 1 m. 2, TiO_2, ferrotitanium, ferromanganese, ferrosilicon, iron, illuminite, aluminum, SiO
_2. Kneading at least one type of powder group consisting of mica, talc, and potassium feldspar and an aqueous solution of at least one type of silicate group consisting of sodium silicate, lithium silicate, and potassium silicate, molding, and drying. A blowhole prevention composition for welding consisting of: