1. Why are there indentation pores on the surface of the flux-cored wire weld?
Because the flux-cored welding wire is a tubular welding wire rolled from a thin steel strip, it belongs to a seam welding wire; the moisture in the air will penetrate into the flux core through the gap, and the welding flux is wet (cannot be dried), resulting in indentation pores in the weld.
2. Why are there technical requirements for CO2 gas purity?
Generally, CO2 gas is a by-product of chemical production, and its purity is only about 99.6%/%. It contains trace impurities and moisture, which will bring defects such as pores to the weld. Welding important products must use gas with CO2 purity ≥ 99.8% per cent, with less pores in the weld, low hydrogen content, and good crack resistance.
3. Why MAG welded joints have higher impact toughness than CO2 welded joints?
During MAG welding, the active gas is only 20%, the transition coefficient of alloy elements in the welding wire is high, and the impact toughness of the weld is high. The active gas of CO2 welding is 100%, the manganese and silicon alloy elements in the welding wire are combined with deoxidation, the transition coefficient of the alloy elements is slightly lower, and the impact toughness of the weld is not as high as that of MAG welding. Such as Tangshan Kobelco MG-51T welding wire (equivalent to ER50-6) its impact toughness value at room temperature: MAG: 160J; CO2: 110J.
4. What is flux-cored wire?
It is a kind of welding wire made by rolling a thin steel strip into a round steel pipe and filling it with a certain composition of powder at the same time.
5. Why is the flux cored wire protected by CO2 gas?
There are two types of flux-cored welding wire according to the protection method: flux-cored gas-shielded welding wire and flux-cored self-shielded welding wire. Flux cored gas shielded welding wire is generally protected by CO2 gas, which belongs to the form of combined gas and slag protection, with good weld formation and high comprehensive mechanical properties.
6. Why are there indentation pores on the surface of the flux-cored wire weld?
Because the flux-cored welding wire is a tubular welding wire rolled from a thin steel strip, it belongs to a seam welding wire; the moisture in the air will penetrate into the flux core through the gap, and the welding flux is wet (cannot be dried), resulting in indentation pores in the weld.
7. Why are there higher technical requirements for the purity of argon?
A: There are currently three types of argon on the market: ordinary argon (about 99.6% purity), pure argon (about 99.9% purity), and high-purity argon (99.99% purity). The first two can weld carbon steel and stainless steel; Non-ferrous metals such as aluminum alloys, titanium and titanium alloys must use high-purity argon; avoid welding seams and heat-affected zones from being oxidized and unable to be welded.
8. Why do TIG welding nozzles have various sizes?
There are 4-8﹟ five specifications of nozzles, 4-5﹟ nozzles can be used for welding carbon steel, 6-7﹟ large nozzles should be used for welding stainless steel and aluminum and aluminum alloys to strengthen the protection range of welds and heat-affected zones . When welding non-ferrous metals such as titanium and titanium alloys, 7-8﹟ larger nozzles should be used to prevent the weld and heat affected zone from being oxidized.
9. What is an acid electrode?
Electrodes containing a lot of acidic oxides in the coating, such as junction 422 (E4303), junction 502 (E5003) and other AC and DC electrodes.
10. What is an alkaline electrode?
Electrodes that contain a lot of alkaline oxides and fluorides in the coating, such as junction 507 (E5015), junction 506 (E5016) and other electrodes.
11. What is a cellulose type (for downward vertical welding) electrode?
Electrodes containing a large amount of organic substances in the coating are specially used for downward vertical welding of pipelines and thin-plate structures. <1> Such as E6010 (equivalent to E4310, J425G) is suitable for backing welding, heat welding and filling welding. <2> E8010 (equivalent to E5511, J555) is suitable for thermal welding, filling welding and cover welding. Generally, low hydrogen down electrode is used for cover welding; E7048 (equivalent to J506X) weld appearance is neat and beautiful.
12. Why should the electrode be dried strictly before welding?
The welding rod often deteriorates the process performance due to moisture absorption, resulting in unstable arc, increased spatter, and prone to defects such as pores and cracks. Therefore, the electrode must be dried strictly before use. Generally, the drying temperature of acid electrode is 150--200 ℃, and the time is 1 hour; the drying temperature of alkaline electrode is 350--400 ℃, and the drying time is 1--2 hours. After drying, put it in an incubator of 100--150 ℃ Inside, take as you go