Welding material knowledge

welding material 

What is welding material? What content is included?

Answer: Welding materials include welding rods, welding wires, fluxes, gases, electrodes, liners, etc.

What is welding wire?

Answer: The metal wire used as a filler metal during welding and for conducting electricity is called welding wire. There are two types of welding wires: solid wire and flux cored wire. Common solid welding wire model: ER50-6 (grade: H08Mn2SiA).

Why do MAG welded joints have higher impact toughness than CO2 welded joints?

Answer: When 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 seam is high. The CO2 welding active gas is 100%, and the manganese and silicon alloy elements in the welding wire are deoxidized together. 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. For example, Tangshan Shensteel MG-51T welding wire (equivalent to ER50-6) has a room temperature impact toughness value of MAG: 160J; CO2: 110J.

What is flux cored welding wire?

Answer: A type of welding wire made by rolling thin steel strips into circular steel pipes and filling them with a certain amount of powder, and then drawing them.

Why is CO2 gas protection used for flux cored welding wire?

Answer: According to the protection method, there are two types of flux cored welding wire: flux cored gas shielded welding wire and flux cored self-protection welding wire. Gas shielded welding wire with flux core is generally protected by CO2 gas, which belongs to the form of gas slag joint protection. The weld seam is well formed and the comprehensive mechanical properties are high.

Why do pressure marks and pores appear on the surface of the weld seam of flux cored welding wire?

Answer: Because flux cored welding wire is a tubular welding wire rolled from thin steel strip, it belongs to seam welding wire; The moisture in the air will invade the flux core through the gaps, making the solder moist (unable to dry) and causing pressure marks and pores in the weld seam.

Why are there technical requirements for the purity of CO2 gas?

Answer: Generally, CO2 gas is a byproduct of chemical production, with a purity of only about 99.6%. It contains trace impurities and moisture, which can cause defects such as porosity in the weld seam. When welding important products, it is necessary to use a gas with a CO2 purity of ≥ 99.8%. The weld has fewer pores, low hydrogen content, and good crack resistance.

Why is there a high technical requirement for the purity of argon gas?

Answer: Currently, there are three types of argon gases on the market: regular argon (with a purity of about 99.6%), pure argon (with a purity of about 99.9%), and high-purity argon (with a purity of 99.99%). The first two can be welded to carbon steel and stainless steel; High purity argon must be selected when welding non-ferrous metals such as aluminum and aluminum alloys, titanium and titanium alloys, etc; To avoid oxidation of the weld seam and heat affected zone, welding cannot be carried out.

Why do TIG welding nozzles come in various sizes and specifications?

Answer: There are five specifications of nozzles, 4-8 #. 4-5 # nozzles can be used for welding carbon steel, and 6-7 # nozzles should be used for welding stainless steel and aluminum and aluminum alloys to strengthen the protection range of the weld and heat affected zone. Welding of non-ferrous metals such as titanium and titanium alloys should use nozzles with a size of 7-8 # or larger to prevent oxidation of the weld and heat affected zone.

10. What is an acidic welding rod?

Answer: Welding rods with high levels of acidic oxides in the coating, such as junction 422 (E4303), junction 502 (E5003) and other AC/DC dual-purpose welding electrodes

11. What is alkaline welding rod?

Answer: Welding rods that contain a large amount of alkaline oxides and fluoride in the coating, such as J507 (E5015), J506 (E5016) and other welding electrodes.

12. What is a cellulose type (downward vertical welding specialized) welding rod?

Answer: Welding rods containing high amounts of organic matter in the coating are specialized for downward vertical welding of pipelines and thin plate structures.

E6010 (equivalent to E4310, J425G) is suitable for bottom welding, hot welding, and filler welding.

E8010 (equivalent to E5511 and J555) is suitable for hot welding, filler welding, and cover welding layers.

Generally, low hydrogen downward welding rods are used for cover welding; E7048 (equivalent to J506X) has a clean and aesthetically pleasing weld appearance.

Why do welding rods need to be strictly dried before welding?

Answer: Welding rods often deteriorate their process performance due to moisture absorption, causing unstable arcs, increased splashing, and easily producing defects such as pores and cracks. Therefore, welding rods must be strictly dried before use. The drying temperature of general acidic welding rods is 150-200 ℃, and the time is 1 hour; The drying temperature of alkaline welding rods is 350-400 ℃, with a time of 1-2 hours. After drying, they are placed in an insulation box at 100-150 ℃ and can be taken as needed.