Welding materials

1. What is welding material? What does it include? Answer: Welding materials include welding rods, welding wires, flux, gas, electrodes, gaskets, etc.

2. What is welding wire? Answer: The metal wire used as filler metal and for conducting electricity during welding is called welding wire. There are two types: solid welding wire and flux-cored welding wire. Commonly used solid welding wire model: ER50-6 (brand: H08Mn2SiA).

3. Why does the impact toughness of MAG welding joints higher than that of CO2 welding joints? Answer: During 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 active gas of CO2 welding is 100%, and the manganese and silicon alloy elements in the welding wire are jointly deoxidized. Its 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 Kobelco MG-51T welding wire (equivalent to ER50-6) has the following room temperature impact toughness values: MAG: 160J; CO2: 110J.

4. What is flux-cored welding wire? Answer: A type of welding wire made by rolling a thin steel strip into a round steel tube and filling it with a certain amount of powder.

5. Why is flux-cored welding wire protected by CO2 gas? Answer: There are two types of flux-cored welding wires 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 gas-slag combined protection, with good weld formation and high comprehensive mechanical properties.

6. Why are there technical requirements for the purity of CO2 gas? Answer: Generally, CO2 gas is a by-product of chemical production, with a purity of only about 99.6%, containing trace impurities and moisture, which will cause defects such as pores in the weld. When welding important products, you must use CO2 gas with a purity of ≥99.8%, which has fewer pores in the weld, low hydrogen content, and good crack resistance.

7. What is an acidic electrode? Answer: A welding rod with a large amount of acidic oxides in the coating, such as E422 (E4303), E502 (E5003) and other AC and DC dual-purpose welding rods.

8. What is an alkaline electrode? Answer: A welding rod with a large amount of alkaline oxides and fluorides in the coating, such as E507 (E5015), E506, (E5016) and other welding rods.

9. Why should the welding rod be strictly dried before welding? Answer: The welding rod often deteriorates its process performance due to moisture absorption, causing arc instability, increased spatter, and easy to produce defects such as pores and cracks. Therefore, the welding rod must be strictly dried before use. Generally, the drying temperature of acid welding rods is 150-200℃, and the time is 1 hour; the drying temperature of alkaline welding rods is 350-400℃, and the time is 1-2 hours. After drying, they are placed in an insulation box at 100-150℃ and can be taken out when needed.