JP2584980B2 - Prevention of blowholes and pits in arc welding - Google Patents

Description

The present invention relates to a method for preventing the occurrence of blowholes and pits which are serious defects in arc welding.

Conventional technology and its problems When performing arc welding using a solid wire or a flux-cored wire, etc., if primer coating is applied to the welded portion or if a galvanized layer is provided, these will vaporize during welding. The fact that blowholes and pits are likely to be generated is a bigger problem than before.

The occurrence of these blowholes and pits leads to a decrease in joint strength and requires rework.However, this requires a great deal of man-hours to cut out the defective spots, repair them, and further adjust the bead shape. is there.

As a method of solving this, there is a method of burning off the primer and the galvanized layer on the welding line with a gas burner etc. before welding, but it also requires a lot of man-hours, and it also requires a primer and galvanizing other than on the welding line. This also damages the layer and impairs rust prevention and appearance.

In addition, there is a means to perform finish welding after decomposing the primer or galvanized layer of the welded part with arc by preceding welding, but it also increases the man-hours and at the same time increases the excess capacity, setting welding conditions It takes time and trouble.

In addition, there is a method of peeling off the primer or galvanizing using a peeling agent before welding, but it is necessary to wipe off and wash the reaction residue after applying and reacting the peeling agent, and furthermore, the peeling agent Contains a large amount of organic solvents, acids and alkalis, and thus tends to impair the working environment and safety.

By the way, JP-A-61-30286 discloses a composition for preventing blowholes, which is used for welding before welding.
O ₂ , ferrotitanium, ferromanganese, ferrosilicon,
This is a method of spraying powders such as iron, illuminite, aluminum, SiO ₂ , mica, talc, and potassium feldspar. It is to float with it. However, the method disclosed in this publication has a serious drawback that the bead shape is not contaminated because of causing agitation, and that the occurrence of spatter is increased.

The present invention has been made in order to solve the above-mentioned drawbacks of the prior art, and prevents the occurrence of blowholes and pits by a simple operation even when a primer coating or a galvanized layer is present in a welded portion. It is an object of the present invention to provide a method for preventing the occurrence of blowholes and pits in arc welding, which can improve the efficiency of the welding operation.

(B) Configuration of the invention The configuration of the present invention is a method for preventing welding defects using phosphorous iron as an active ingredient, and applying the phosphorous iron at a rate of 0.1 to 10 g per meter along a welding line, prior to welding, spraying, Or blow hole pits in arc welding characterized in that they are supplied by dispersion plating, filled inside the welding wire, or supplied together with the welding wire by applying to the surface of the welding wire. The gist of the invention is a method of preventing the occurrence of phenomena.

Means to solve the problem The zinc in the galvanized or zinc-rich primer is vaporized by the heat of the arc welding, but by supplying phosphorous iron onto the welding line prior to or during welding, this zinc is removed. They found that vaporization was suppressed, and reached the present invention.

Phosphorus iron in the present invention is a mixture of Fe ₂ P and FeP, and usually contains 20 to 28% of phosphorus.

The present invention is a method for preventing welding defects using iron phosphate as an active ingredient.Hereinafter, phosphorus iron itself or a solvent or a binder is blended with the iron phosphate as necessary to supply the iron phosphate onto the welding wire. These will be described with reference to the present inhibitor.

When the inhibitor of the present invention is supplied on a welding line, it is preferable to supply the phosphorous iron in a range of 0.1 to 10 g per meter along the welding line.

That is, if the amount of phosphorous iron on the welding line is 0.1 g / m or less, there is no effect, and if the supply amount exceeds 10 g / m, the shape of the bead becomes poor, the unevenness becomes large, and the bead appearance becomes poor.

Although the inhibitor of the present invention contains phosphorous iron as an active ingredient, as described above, appropriate additives such as water, a solvent, an adhesive, and a dispersant may be added as necessary to supply the iron on the welding wire. Of course, it is effective to add an adhesive such as ethyl silicate or organic titanate, which forms an inorganic continuous film when dried, since it does not generate gas from itself. .

As a means for supplying the inhibitor of the present invention onto the welding line, the powder may be sprayed as it is prior to welding, or a suspension may be applied by spraying with a spray gun or the like or applied with a brush, and adhered.
Further, the means for supplying during welding may be applied to the surface of the wire as a component of the coating material or may be filled inside.

In addition, in order to apply to the wire surface as a component of the coating material, a predetermined amount of this iron phosphate powder is mixed and dispersed in a flux used as the coating material to prepare a paste-like coating material,
The paste may be applied in a desired amount around the wire by brushing or dipping.As a means for further filling the inside of the wire, a method of forming a hollow wire and filling the hollow with a desired amount of phosphorous iron powder, And the like.

Further, the active ingredient, phosphorus iron, may be contained in advance in the form of dispersion plating during the production of a galvanized steel sheet, or may be further applied to the steel sheet.

The welding method to which the inhibitor of the present invention is applied is not particularly limited as long as it is an arc welding method, and can be suitably used for, for example, a submerged arc welding method, a gas shielded arc welding method, or a manual welding method. Things.

Action The present invention is configured as described above, and by supplying the inhibitor of the present invention to a welded portion, by the following action,
Blowholes and pits can be prevented from being generated, and the bead appearance is not adversely affected.

Generally, blow holes and pits are generated in arc welding for the following reasons.

In other words, the zinc in the primer and galvanized layer is
Since its melting point is 420 ° C and its boiling point is 930 ° C, it is very low compared to the melting point of carbon steel of about 1500 ° C and its boiling point of about 2000 ° C or more, so arc welding of galvanized steel sheets and zinc-rich primer coated steel sheets Then, the zinc vaporizes and evaporates first to form a gas, but the carbon steel is only molten, and as soon as the arc passes, it solidifies and traps the zinc gas inside, which is a pit. Or blowholes.

In other words, zinc gas is not discharged and volatilized from the weld before the weld is solidified.If this gas is completely trapped, it becomes a blowhole, and the discharged part solidifies the metal. If is not filled, it becomes a pit.

However, when the inhibitor of the present invention is supplied to this weld, the iron phosphate, which is an active ingredient, reacts with zinc and molten iron to form a phosphorus-zinc-iron compound and has a higher melting point than zinc.・ Becoming a ternary compound having a boiling point, the melting point and boiling point of which are almost the same as the melting point and boiling point of carbon steel, exhibit uniform melting and evaporation, and zinc is directly vaporized. As a result, there is no phenomenon that zinc gas is trapped, so that pits and blow holes can be prevented.

In this case, when the above-mentioned ternary compound is uniformly dispersed throughout the entire welded portion, the above-mentioned action is of course exerted sufficiently. Even in the case where carbon steel is covered therearound, similar effects are exerted because there is no difference in melting point and boiling point.

In addition, other phosphorus compounds may be considered as substances exhibiting the above-mentioned effects, that is, for example, aluminum phosphide, indium phosphide, uranium phosphide, osmium phosphide, cadmium phosphide, potassium phosphide, gallium phosphide , Calcium, gold, silver, chromium, chromium, cobalt, zirconium, mercury, tin, tungsten, titanium, thorium, thorium, nickel, and phosphorus Neptunium, platinum, vanadium, barium, bismuth, arsenic, boron, magnesium, manganese, molybdenum,
Metal phosphide compounds such as lithium phosphide, ruthenium phosphide, and rhenium phosphide are known, but they are economical, toxic to the human body, stable in the atmosphere, and used with chemicals such as water and acids and alkalis. In view of the reactivity, in the present invention, it was determined that iron phosphate was the most practically preferable, and only iron phosphate was selected as the active ingredient of the present invention.

In addition, although phosphorus alone may be possible, toxicity to the human body,
It was judged that there was a practical problem from the stability in the air and the reactivity with water, chemicals such as acids and alkalis, and this was also excluded.

Example 1 An inhibitor of the present invention having the following composition was prepared.

Phosphorus iron (containing P = 25%) 70 parts (under 200 mesh) Ethyl silicate-based binder 60 parts (Ethyl silicate hydrolyzate) (Non-volatile content 10%) Isopropyl alcohol 520 parts These are kneaded with a stirrer to obtain a uniform suspension. The product was made and subjected to the following welding test.

Laminated joints are formed by laminating galvanized steel sheets with a thickness of 3 mmt and a galvanized film thickness of 6 μm, and the above-mentioned suspension is applied on the welding line so as to have various amounts of phosphorus iron as shown in the upper row of Table 1. After coating and drying, welding was performed.

The welding conditions were 200A, 23V, DC reverse polarity, welding speed 1
m / min, carbon dioxide gas flow rate 20 l / min, and a 1.2 mm diameter solid wire (YGW-12).

 Table 1 shows the results.

However, the numerical values 0 and 0 in the column of phosphorus iron adhesion amount in Table 1 were used.
08, 12.0 are comparative examples, and other 0.1, 0.5, 1,
Five and five examples are examples.

Example 2 An inhibitor of the present invention having the following composition was prepared.

Phosphorus iron (containing P = 25%) 70 parts (under 350 mesh) Titanate binder 45 parts (tetrakis titanium) (nonvolatile content 14%) 1,1,1-trichloroethane 300 parts A turbid material was prepared and subjected to the following welding test.

12mm thick zinc-rich primer coated steel plate (film thickness 20
The above suspension was applied to both sides of the T-type spot fillet welded test piece of μ) on the welding line so as to have various amounts of phosphorous iron as shown in the upper row of Table 2, and then horizontal spot fillet welding was performed.

The welding conditions were 250 A, 28 V, DC reverse polarity, welding speed 9
The measurement was performed using a solid wire (YGW-11) having a diameter of 1.2 mm at 0 cm / min, a carbon dioxide gas flow rate of 20 l / min.

 Table 2 shows the results.

However, the numerical values 0, 0, and 0 in the column of phosphorus iron adhesion amount in Table 2.
Three examples 07 and 13 are comparative examples, and the other three examples 0.1, 2 and 10 are examples.

(C) Effects of the Invention The present invention is as described above, and as clearly seen in the examples, by supplying an appropriate amount of the inhibitor of the present invention onto the welding line, generation of blowholes and pits is completely prevented. In addition, the bead appearance is good, and no other welding defects occur.

As described above, the inhibitor of the present invention is supplied to a weld portion prior to or during welding when a steel material having a primer coating or a galvanized layer is arc-welded, and is blown by a simple operation. It is capable of preventing welding defects such as holes and pits, and also has a very remarkable effect, such as an improvement in the efficiency of welding work.

 ──────────────────────────────────────────────────続 き Continued on front page (72) Inventor Katsuaki Nakatsuji 1-chome, Mizushima-Kawasaki-dori, Kurashiki-shi (No address) Inside Mizushima Works, Kawasaki Steel Corp. Inside the research institute (72) Inventor Tadashi Nakajima 3-29 Minamimikunigaokacho, Sakai

Claims (1)

(57) [Claims] 1. A method for preventing welding defects comprising phosphorous iron as an active ingredient, wherein said phosphorous iron is applied, sprayed or dispersed-plated along a welding line at a rate of 0.1 to 10 g / m prior to welding. A method for preventing blowholes and pits from being generated in arc welding, wherein the supply is performed together with the welding wire, or the inside of the welding wire is supplied, or the coating is supplied to the surface of the welding wire together with the welding wire.