Iron-based core flux-coated electrode free of pre-welding drying and easy to weld

Abstract

The invention belongs to the technical field of welding materials, and particularly relates to an iron-based core flux-coated electrode free of pre-welding drying and easy to weld. The iron-based coreflux-coated electrode comprises an iron-based core, a coating and a polyaniline protective film, wherein the coating wraps the periphery of a welding section of the iron-based core, and the polyaniline protective film wraps the exposed part of the iron-based core and the outer surface of the coating. The polyaniline protective film comprises the following components in percentage by mass: 6%-10%of nano copper wires treated by a coupling agent, 12.5%-15.5% of carbon fibers treated by the coupling agent, 20%-36% of conductive polyaniline treated by the coupling agent, 0.8%-1.5% of lanthanum and/or cerium, 8%-10% of a curing agent and the balance of epoxy resin. The flux-coated electrode does not need to be dried before welding, arc striking is easy in the welding process, electric arcs arestable in the welding process, and the obtained weld joint is high in mechanical property. The flux-coated electrode disclosed by the invention is an innovation in the aspect of flux-coated electrodes.

Description

technical field [0001] The invention belongs to the technical field of welding materials, in particular to an iron-based welding core coated welding rod which is dried before welding and is easy to weld. Background technique [0002] The coated electrode is composed of two parts, the metal welding core and the coating. The coating is evenly and centripetally pressed on the metal welding core outside the metal welding core. The metal welding core is usually a wire with a certain length and diameter. When welding, the wire should conduct the welding current, generate an arc between the workpiece and the end of the electrode, and convert the electrical energy into heat energy. In addition, it will also melt itself as a filler. The metal is fused with the liquid parent metal to form a weld. At present, the largest amount used in industrial production is the iron-based welding core coated electrode, that is, the main element of the wire that makes up the welding core is iron. ...

AI Technical Summary

Problems solved by technology

Due to the limited storage and use conditions, the electrode will inevitably absorb moisture after being in contact with the air for a period of time, causing an increase in the moisture content of the coating

After the coating of the electrode is wet, "white flowers" will easily appear on the surface, or the coating of the electrode will stick, pulverize and fall off, which will seriously affect the performance of the electrode.

The moisture absorption of the electrode will lead to the increase of moisture, the formation of pores in the weld during welding, and the increase of the hydrogen content in the deposited metal composition of the weld, which will affect the mechanical properties of the welded joint

Therefore, the welding rod must be dried before welding, and it can be used as soon as it is dried. The drying temperature is generally about 400 ° C, and the holding time is generally about 1.5 hours. This causes great inconvenience to the operator

In field construction occasions, the moisture absorption of electrodes is more serious

In addition, some welding rods have very strong moisture absorption ability, and often reabsorb moisture in a short time after drying, which affects the quality of welded joints after welding

Drying of welding rods requires additional drying equipment. When using them, the welding rods need to be placed in the insulation tube to continue to keep warm, and different types of welding rods must be dried separately, which is complicated to use and consumes a lot of electric energy. It does not conform to the national policy of energy saving and consumption reduction.

[0005] 2) Arc striking is difficult

However, due to the inevitable contact with the atmosphere, water vapor and other media during the storage and transportation of the electrode after manufacture, the end face of the iron-based welding core at the arc-starting end of the electrode is exposed, which will easily cause the oxidation of the end face of the iron-based welding core, and cause contact with the workpiece When arcing, it will be difficult to form a circuit between the electrode and the workpiece due to the existence of the oxide layer, and it is not easy to start the arc

[0006] 3) Poor arc stability during welding

[0008] The Chinese patent application number 201780045171.8 (application date: July 5, 2017) discloses a coated electrode. The iron-based welding core in the clamping part of the electrode is covered with a film layer containing a Ca compound, which can prevent the Fe contained in the electrode core from Oxidation, the iron-based welding core of the electrode clamping part is difficult to form an oxide film, and the stability of the arc is improved, but the main technical proposal has the following problems: ①It must be dried before welding: the coating of the electrode will still be used after manufacture Before absorbing moisture, it must be dried before welding; ② Difficulty in arc ignition: the iron-based welding core at the arc-starting end of the electrode is exposed and uncoated, which will cause oxidation of the end surface of the iron-based welding core and make it contact with the workpiece Due to the existence of the oxide layer during arc ignition, it is difficult to form a loop between the electrode and the workpiece, and arc ignition is difficult; ③ Difficulty in preparation: In this technical solution, there are strict requirements on the thickness of the coating layer, surface roughness, and area ratio. The process is difficult and the production cost is high; 4. it is inconvenient to use: it is described in the 0016th paragraph of the patent specification that "although the coated electrode of the present invention is difficult to peel off the film layer containing the Ca compound until the welding is used, when welding, only by Hold it with welding pliers and apply pressure, and you can easily peel off the film layer, so that a stable arc occurs", clearly explaining that the film layer is peeled off from the iron-based welding core by holding it with welding pliers and applying pressure, but in In practical applications, this technical effect is difficult to achieve, because it is difficult to peel off the film layer from the iron-based solder core by holding it with welding tongs and applying pressure. Even if it is partially peeled off, the peeled film layer will not fall off, and the film layer will remain. Between the welding tongs and the iron-based welding core, you can only use the welding tongs to hold and apply pressure, rotate the electrode while keeping the welding tongs still, and use the wires at the clamped part of the welding tongs to separate the coating layer from the iron-based core. Then release the welding tongs to let the film layer fall, clamp the welding tongs again to exert pressure on the iron-based welding core that has been removed from the film, so as to achieve the tight contact between the welding tongs and the iron-based welding core without the coating layer. Carry out welding, so as to achieve the purpose of keeping the welding arc stable, this method is complicated to operate and low in work efficiency

[0009] The Chinese patent with application number 201110005031.2 (application date January 12, 2011) discloses a method for preparing an anti-moisture protection film for welding rods with lauric acid. 3 o 4 Powder and lauric acid petroleum ether solution, then take out and dry to make lauric acid form an anti-moisture absorption protective film on the surface of the electrode. The main inventor of this patent also published "Research on the Anti-moisture Absorption Film of Electrode Prepared by Microwave Reaction of Lauric Acid" ( Electric welding machine, October 2011, Vol. 41, No. 10) and other related papers have carried out a more in-depth elaboration on it, but the technical solution has the following problems: ① Difficulty in starting the arc: it is stated in paragraph 0004 of the manual that "the welder is using It can be used directly without using an oven and rebaking", Fe 3 o 4 Powder and lauric acid form an anti-moisture absorption protective film on the surface of the electrode, Fe 3 o 4 And the conductivity of lauric acid is poor, resulting in extremely poor conductivity of the anti-moisture absorption protective film. If the anti-moisture absorption protective film is not dried, the anti-moisture absorption protective film will always exist. Poor electrical conductivity, which leads to difficulty in arc ignition; ② Poor arc stability during welding: the same reason will cause poor conductivity of the clamping end of the electrode, and unstable arc during welding; ③ Poor safety: Paragraph 0008 of the manual describes "oil Ether is highly volatile. Petroleum ether vapor and air can form explosive mixtures, which can easily cause combustion and explosion when exposed to open flames or high heat energy, and can also cause combustion and explosion when encountering static electricity spark discharge. During the preparation process, especially in the industrial production process, A large amount of petroleum ether vapor will be produced, which is a high-risk operation with poor safety; ④ Harmful to human health: lauric acid is irritating to the eyes, skin, mucous membranes and upper respiratory tract, which is not conducive to the health of electrode preparation personnel and welding operators

[0010] The Chinese patent with application number 200420054823.4 (application date on December 30, 2004) discloses a drying-free electrode, which is coated with a layer of paraffin on the surface of the electrode coating, and the electrode can be directly welded without re-drying, but the The technical solution has the following problems: ① Difficulty in arc ignition: The arc ignition end of the electrode is pointed and wrapped in paraffin wax. The main component of paraffin wax is straight chain alkane, which has poor conductivity. The arc ignition end of the electrode is wrapped by this material, which will cause difficulty in arc ignition If the arc striking end is pointed, it is easy to damage the non-welding surface of the workpiece during the arc striking process; ②The welding arc is unstable: the iron-based welding core at the clamping end of the electrode has not taken any protective measures, and the oxidation of the iron-based welding core will cause welding tongs Poor contact with the clamped iron-based welding core, and the arc is unstable during welding; ③It has a great influence on the mechanical properties of the weld: paraffin is brittle and difficult to make a film, so it will be more difficult to wrap it outside the coating. Large thickness, because its main component is carbon, so that part of the carbon will generate carbon dioxide during welding, and a large part of the incompletely burned carbon will dissolve into the deposited metal, resulting in an excessive increase in the carbon content of the deposited metal. Large, it has a great influence on weld crack sensitivity and weld impact resistance

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