JPS637878B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention improves productivity by improving the adhesion of the coating material, and also provides a non-woven material that significantly improves the flexibility and stick-scorch resistance of the coating material when used at high currents. This invention relates to a low-hydrogen coated arc welding rod (hereinafter referred to as a non-low-hydrogen rod). [Prior art] Non-low hydrogen based rods have a higher amount of hydrogen in the weld metal than low hydrogen based arc welding rods, so they have inferior cracking resistance and impact toughness when used with heavily constrained workpieces. It has a very wide range of uses due to its good welding workability. For example, Illuminite welding rods for all positions are used in shipbuilding, bridges, machinery, architecture, pressure vessels, etc., and lime titanium welding rods are used for lightweight steel frames, automobile parts, segments, drums, etc. Suitable for welding middle plates. By the way, in order to improve the productivity of non-low hydrogen rods and the welding workability, for example, Japanese Patent Publication No. 59-2599 discloses that 0.1 to 3% by weight of hectorite is added to the coating material to increase the adhesion of the coating material. It has been shown that it is possible to prevent the coating from falling off during transportation, improve paintability during manufacturing, reduce scratches and dents, and improve production yield. Moreover, since the reserves of this hectorite are extremely limited, there are limits to its application. In addition, to improve the flexibility of the coating material, for example, as described in Japanese Patent Publication No. 54-24974, a mixed additive consisting of an alkaline solution, protein, aluminum salt, and polysaccharide is added to water glass at a concentration of 0.1 to 10%.
Significant improvement was achieved by using % by weight as a sticking agent. However, when non-low hydrogen rods using this adhesive are used at high currents, the organic matter in the coating material in the latter half of the welding rod decomposes and burns due to Joule heat, which tends to cause what is called a burnt phenomenon. The disadvantage of using this is that the arc becomes unstable during welding. Therefore, JP-A-57-
No. 206595 uses water glass with a high molar ratio of SiO ₂ /Na ₂ O of 2.8 to 3.8 as a fixing agent to prevent stick burn.
However, as described in JP-A-57-100896, increasing the molar ratio of water glass causes drying cracks during production, and when the molar ratio is high, Na ₂ O, K ₂ O, etc. Since the alkali oxide in the arc decreases, the arc condition deteriorates and spatters become more scattered. In this way, the productivity of the current non-low hydrogen rods is good, the flexibility of the coating material and the resistance to stick burn when used at high currents are improved, and there are other problems such as arc conditions, spatter, slag conditions, bead appearance, etc. It was extremely difficult to satisfy the welding workability. It has been strongly desired by various industries that use welding rods to obtain a welding rod that satisfies all of these requirements. [Problems to be Solved by the Invention] In view of the above-mentioned circumstances, the present invention examines the composition of the coating material, ensures the conventional performance, and improves productivity by making the adhesion of the coating material extremely good. In addition, the coating material has excellent flexibility, which is required when welding in complex and narrow areas, and the coating material has sufficient stick-scorch resistance even when using high currents. The present invention provides a non-low hydrogen rod obtained. [Means for Solving the Problems] In order to meet the above-mentioned demands, the present invention was developed as a result of various studies on coating materials for non-low hydrogen rods. This product has significantly improved stick scorch resistance, and its main point is that the coating material contains 85
Sepiolite of more than % by weight (hereinafter expressed as %)
The non-low hydrogen rod is characterized by containing 0.5 to 5.0% of organic matter and 0.5 to 8.5% of organic matter, and having a ratio of sepiolite to organic matter of 0.3 to 3.5. In order to improve productivity and the flexibility of the coating material, it is extremely effective to make the coating material itself strong in its adhesion and to improve the adhesion between the core wire of the welding rod and the coating material. As a result of various researches, we have found that it is extremely important and highly effective to use sepiolite in combination with organic matter and to limit the ratio of sepiolite to organic matter. Sepiolite is a natural hydrated magnesium silicate with the chemical structure (OH ₂ ) ₄ (OH) ₄ Mg ₈ Si ₁₂ O ₃₀ 6
It is represented by ~8H ₂ O, and its crystal structure is fibrous.It has good dispersibility in water glass, and when added to a coating material, the fibers become entangled in a complicated manner when mixed with water glass. It has the effect of loosening and increasing the viscosity of the coating material. Furthermore, during the drying process during the production of welding rods, sepiolite not only solidifies itself but also solidifies other coating materials. Therefore, since these have good thickening properties and solidifying properties, the coating material has excellent adhesion properties. In addition, as mentioned above, sepiolite contains crystal water, so when welding using high current, when the crystal water is dehydrated from the coating material in the latter half of the welding rod due to the welding heat, heat is released from the coating material. becomes active and has the effect of improving the stick scorch resistance of the coating material. In this way, sepiolite can greatly contribute to improving productivity, flexibility of the coating material, and improvement of stick-scorch resistance during high-current use, but if the sepiolite added to the coating material is coarse particles or is used in large quantities, The arc force weakens and becomes unstable, causing more spatter to fly out. Therefore, it is necessary to limit the grain size and addition amount of sepiolite, and in order to maintain good arc conditions and healthy welding workability, it is necessary to use organic substances in combination, and the ratio of sepiolite to organic substances must be It was confirmed that this is an important requirement. The present invention has been made based on the above findings. Note that the organic substances referred to here refer to starch, cellulose, wood flour, dextrin, sodium alginate, etc., and can be used alone or in various combinations. [Function] The function of the present invention will be described in detail below. In the non-low hydrogen rod of the present invention, the reason why the coating material contains 85% or more of sepiolite particles of 105μ or less is to improve the stability and ease of welding workability, and the adhesion and uniformity of the coating material. This is to improve the production yield and improve the flexibility of the coating material. 15% of particles have a particle size of 105μ or more
In this case, the arc is unstable and spatters are often scattered, and in terms of productivity, the dispersibility of fibrous sepiolite deteriorates and the adhesion of the coating material becomes worse. Scratches, dents, and scratches are more likely to occur on the parts. In addition, the flexibility of the coating material during welding deteriorates and the coating material peels off, and if welded in this state, the coating tube will not be formed, resulting in insufficient shielding and unstable arc directionality, resulting in insufficient penetration into the blowholes in the weld metal. , resulting in welding defects such as deterioration of bead appearance. Next, the amount of sepiolite added was limited to 0.5 to 5.0% in order to make full use of the effects of sepiolite without deteriorating other properties.
If it is less than %, the adhesion of the coating material will be poor, as is the case with conventional coatings.
This leads to a decrease in production yield and deterioration of the flexibility of the coating material.
Furthermore, when welding at a high current, the stick burn resistance of the coating material in unused areas deteriorates, and if used as is, the arc force becomes weak and unstable, resulting in more spatter, and the deoxidizer in the coating material deteriorates during welding. The deoxidation reaction of the metal cannot be carried out sufficiently, causing blowholes and pits to occur. On the other hand, if it exceeds 5.0%, the arc force becomes weak and there are many spatters, and furthermore, the coating material becomes too dense and the surface of the coating material dries first during the drying process, leaving the internal moisture in an undried state. This water is evaporated by drying heat,
When the water vapor pressure inside the coating material exceeds a limit value, the surface of the dried coating material is pierced and dry cracking occurs. The purpose of containing 0.5 to 8.5% of organic matter in the coating material is to ensure arc stability with an appropriate arc force, obtain defect-free weld metal, and contribute to improved productivity; if it is less than 0.5%, the arc force Because of the weak arc, the arc becomes unstable, causing many spatters to fly off, resulting in insufficient penetration and slag entrainment, which impairs welding workability. Furthermore, during the production of welding rods, scratches, dents, and scratches are likely to occur on the surface of the coating material, resulting in a decrease in production yield. On the other hand, if it exceeds 8.5%, even if other components are adjusted, the burn resistance of the unused part of the coating will deteriorate when high current is used, and furthermore, if it is left in the atmosphere after manufacturing or re-drying. The rate of moisture absorption of the coating increases, and if welding continues as it is, the amount of diffusible hydrogen will increase in the weld metal, resulting in poor cracking resistance, blowhole resistance, etc. The ratio of sepiolite to organic matter is 0.3~
The value of 3.5 is important in order to improve productivity, sufficiently satisfy the flexibility of the coating material, and the stick-scorch resistance of the coating material at high currents, and to prevent other performances from deteriorating. If the ratio is less than 0.3, the adhesion of the coating material decreases, and the above-mentioned object of the present invention cannot be achieved.
In particular, the stick burn resistance of the coating during welding deteriorates, resulting in deterioration in welding workability and welding defects. In addition, if the ratio exceeds 3.5, the arc becomes unstable and spatter increases, the arc does not spread and the bead takes on a convex shape, and the arc force becomes weaker, which increases the viscosity of the slag and causes it to melt. The slag becomes easily entangled in the coating tube, resulting in insufficient penetration and slag entrainment. [Example] Based on Examples, the effects of the present invention will be described in more detail by comparing examples of the present invention with comparative examples and conventional examples. Table 1 shows the various particle sizes of sepiolite used in the test, and Table 2 shows the welding rods of the present invention, comparative welding rods, and conventional welding rods in each coating type of illuminite type, lime titania type, and iron powder iron oxide type. This shows the results of each performance test. The test welding rods were manufactured by adding a fixing agent to each of the coating materials shown in Table 2, wet-mixing them, using a mild steel core wire with a diameter of 4.0 mm, and adjusting the length of the wire to be made of illuminite, lime titanium, etc. The type is 400mm,
The size of the iron powder iron oxide type is 550 mm, and after coating with a normal extrusion type coating machine, it is dried at a maximum temperature of 150℃ for the illuminite type and lime titania type, and 190℃ for the iron powder iron oxide type. I made a welding rod. Each test method and its acceptance criteria were as follows. In the coating shedding test to quantify the adhesion of the coating, a product weighing approximately 1.5 kg was placed in a 55 mm x 300 mm x 720 mm steel box made of 6 mm thick plate and heated at a speed of 40 revolutions per minute for 5 minutes. The rate at which the coating material fell off was measured by rotating, and those with a rate of falling off of 2% or less were judged to be good. Regarding the production yield test, approximately 150 kg of welding rods are manufactured, and those with no scratches, dents, scratches, or dry cracks during the painting and drying process are considered good, and the production yield is the ratio of good items to the total welding rods manufactured. Those whose value was 99% or higher were considered good. Regarding the flexibility test of the coating material, the welding rod holder gripping margin 1 is fixed to a part of the fixing jig 4 shown in Fig. 1, and the welding rod is bent into an arc shape toward the other end. The welding rod 2 is bent by being pressed against the arcuate surface of a tubular jig 3 with a diameter of 160 mm as shown in Fig. 1, expressed as a rod bending angle.
It is expressed as the angle (θ) between the extension line of the tip of the welding rod and the welding rod initially set in the jig when the welding rod is stopped with the coating material starting to chip. This is the average value, and those with a bend of 180° were considered good. Next, in the stick burn resistance test of the coating, downward welding was performed using an AC welding machine using a mild steel plate (plate thickness 12 mm, width 100 mm, length 800 mm). Using 200A,
For iron powder iron oxide type, the test is conducted at 180A, and the judgment method is to find the position where the coating agent in the unused part deteriorates and no coating cylinder is formed, and the arc condition suddenly changes and becomes unstable and the arc force starts to decrease. The arc was extinguished at , and the remaining length of the welding rod at that time was expressed as the average value of 10 test welding rods, and a value of 60 mm or less was considered good. Furthermore, for other welding workability tests, we conducted tests on illuminite and lime titanium welding rods.
The tests were carried out at 180A in a downward and horizontal fillet position, and at 150A in a vertical position.For iron powder iron oxide welding rods, both were investigated at 160A in a downward and horizontal fillet position. As for the evaluation method, the welding was judged as good if the arc condition, amount of spatter, slag condition, bead appearance, etc. were all satisfied in each welding position.

【table】

【table】

【table】

〔Effect of the invention〕

As explained above, the welding rod of the present invention overcomes the drawbacks of conventional non-low hydrogen rods, has good adhesion of the coating material, significantly improves productivity and flexibility of the coating material, and has high current resistance. It is possible to provide a welding rod that can significantly improve stick burn resistance, and in welding work, the welding work is easy and can greatly contribute to improving welding work efficiency.

[Brief explanation of the drawing]

FIG. 1 shows a schematic side view of a welding rod bending jig for explaining the flexibility test of a covered arc welding rod. 1... Gripping allowance for welding rod, 2... Welding rod, 3...
Tubular jig, 4... fixed jig.

Claims (1)

[Claims] 1 The coating material contains 0.5 to 5.0% by weight of sepiolite with particles of 105μ or less at 85% by weight or more, and 0.5 to 5.0% by weight of organic matter.
A non-low hydrogen-based coated arc welding rod characterized by containing 8.5% by weight of sepiolite and having a ratio of sepiolite to organic matter of 0.3 to 3.5.