Welding materials

1. What is the welding material? What is included?

Answer: Welding materials include welding rod, welding wire, flux, gas, electrode, gasket, etc.

2. What is the welding wire?

Answer: When welding, it is used as filler metal and at the same time as conductive metal wire-called welding wire. There are two kinds of solid welding wire and flux cored wire. Commonly used solid welding wire model: ER50-6 (brand: H08Mn2SiA).

3. Why is the impact toughness of MAG welded joints higher than that of CO2 welded joints?

Answer: When MAG welding, the active gas is only 20%, the alloy element transition coefficient in the welding wire is high, and the impact toughness of the weld is high. The CO2 welding active gas is 100%, the manganese and silicon alloy elements in the welding wire are deoxidized together, the alloy element transition coefficient is slightly lower, and the impact toughness of the weld is not as high as that of MAG welding. For example, Tangshan Shengang MG-51T welding wire (equivalent to ER50-6) has a normal temperature impact toughness value of MAG: 160J;CO2: 110J.

4. What is flux cored wire?

Answer: A kind of welding wire made of thin steel strip rolled into a round steel pipe, filled with a certain composition of powder at the same time.

5. Why is flux-cored wire shielded with CO2 gas?

Answer: There are two types of flux-cored wire according to the protection method: flux-cored gas shielded wire and flux-cored self-shielded wire. Flux-cored gas shielded welding wire is generally protected by CO2 gas, which belongs to the form of gas-slag joint protection, with good weld formation and high comprehensive mechanical properties.

6. Why is there indentation porosity on the weld surface of flux-cored wire?

Answer: Because flux-cored welding wire is a tubular welding wire made of thin steel strips, it belongs to seamed welding wire. Moisture in the air will invade the flux core through the gap, and the welding flux will be wet (unable to dry), resulting in indentation pores in the weld.

7. Why is there a technical requirement for CO2 gas purity?

A: Generally, CO2 gas is a by-product of chemical production with a purity of only about 99.6. It contains trace impurities and moisture, which will bring defects such as pores to welds. Important welding products must be selected CO2 purity ≥ 99.8% of the gas, weld porosity, low hydrogen content, good crack resistance.

8. Why are there higher technical requirements for argon purity?

Answer: At present, there are three kinds of argon on the market: ordinary argon (purity of about 99.6), pure argon (purity of about 99.9) and high purity argon (purity of 99.99). The first two kinds can weld carbon steel and stainless steel. High purity argon must be used for welding non-ferrous metals such as aluminum and aluminum alloy, titanium and titanium alloy. Avoid oxidation of welds and heat affected areas and cannot be welded.

9. Why TIG welding nozzles have many sizes and specifications?

Answer: There are 4-8# five specifications of the nozzle, welding carbon steel can choose 4-5# nozzle, welding stainless steel and aluminum and aluminum alloy should choose 6-7# large nozzle, in order to strengthen the weld and heat affected zone protection range. Welding titanium and titanium alloy and other non-ferrous metals should be selected 7-8# larger nozzle, in order to prevent the weld and heat affected zone is oxidized.

10. What is acid electrode?

Answer: welding rods containing a large amount of acidic oxides in the coating, such as AC/DC dual-purpose welding rods such as junction 422(E4303) and junction 502(E5003).

11. What is alkaline electrode?

Answer: The coating contains a large amount of alkaline oxide and fluoride electrodes, such as 507 electrodes (E5015) and 506 electrodes (E5016).

12. What is cellulose type (special for vertical welding) electrode?

Answer: The welding rod containing a large amount of organic matter in the coating is specially used for vertical welding of pipes and sheet structures.

<1> such as E6010 (equivalent to E4310, J425G) is suitable for bottoming welding, thermal welding and filling welding.

<2> E8010 (equivalent to E5511, J555) is suitable for thermal welding, filling welding, cover welding layer.

Generally with low hydrogen downward welding strip cover welding; E7048 (equivalent to J506X) weld appearance clean and beautiful.

13. Why should the welding rod be strictly dried before welding?

Answer: 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 strictly dried before use. Generally, the drying temperature of acidic electrode is 150-200 ℃ for 1 hour. The drying temperature of alkaline electrode is 350-400 ℃ for 1-2 hours. After drying, it is placed in an incubator at 100-150 ℃ and taken as needed.