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What is welding material? What is included? A: Welding materials include electrodes, welding wire, flux, gases, electrodes, backing pads, etc. Q2 What is welding wire? A: The metal wire used as filler material during welding and also for conducting electricity is called welding wire. It is divided into solid wire and flux-cored wire. Common solid wire grades: ER50-6 (grade: H08Mn2SiA). Q3: Why do MAG welded joints have higher impact toughness than CO2 welded joints? A: During MAG welding, the active gas constitutes only 20%; the transition coefficient of alloying elements in the wire is high, resulting in high impact toughness of the weld. The active gas for CO2 welding is 100%; manganese and silicon, which are alloying elements in the wire, work together for deoxidation. The transition coefficient of these alloying elements is slightly lower, resulting in weld impact toughness that is not as high as that of MAG welding. For example, the Tangshan Shinko MG-51T welding wire (equivalent to ER50-6) has the following impact toughness value at room temperature: MAG: 160J ； CO2: 110J. Q4 What is flux-cored wire? A: A type of welding wire made by rolling thin steel strips into circular steel tubes, filling them with a powder of specific composition, and then drawing them. Q5 Why is CO2 gas used for shielding flux-cored wires? A: Based on the protection method, flux-cored wires are divided into two types: flux-cored gas-shielded welding wires and flux-cored self-shielded welding wires. Flux-cored gas shielded welding wires generally use CO2 gas for protection, employing a combined gas-slag shielding method; they result in well-formed welds and possess high overall mechanical properties. Q6 Why do dented pores appear on the surface of welds made with cored wire? A: Since cored wire is a tubular wire made by rolling thin steel strips, it belongs to seamed wire ； Moisture in the air can penetrate into the core through gaps, causing the flux to become damp (unable to be dried), which results in indentations and pores in the weld seam. Q7 Why are there technical requirements for the purity of CO2 gas? A: Generally, CO2 gas is a by-product of chemical manufacturing, with a purity of only around 99.6%; it contains trace amounts of impurities and moisture, which can cause defects such as pores in the welds. When welding important products, it is essential to use gas with a CO2 purity of ≥99.8% – this results in fewer weld porosities, a lower hydrogen content, and improved crack resistance. Q8 Why are there high technical requirements for argon purity? A: There are currently three types of argon available on the market: regular argon (with a purity of around 99.6%), pure argon (with a purity of around 99.9%), and high-purity argon (with a purity of 99.99%). The first two types can be used for welding carbon steel and stainless steel ； When welding non-ferrous metals such as aluminum and aluminum alloys, as well as titanium and titanium alloys, high-purity argon must be used ； Prevent oxidation of the weld seams and heat-affected zones, which would make welding impossible. Q9 Why are there various sizes of TIG welding nozzles? A: There are 4–8 different sizes of nozzles available. For welding carbon steel, nozzles of size 4–5 can be used, while for welding stainless steel, aluminum, and aluminum alloys, larger nozzles of size 6–7 should be employed to enhance the coverage of the weld seam and the heat-affected zone. When welding non-ferrous metals such as titanium and titanium alloys, a nozzle with a size of 7–8# or larger should be used to prevent oxidation of the weld seam and heat-affected zone. Q10: What is an acidic welding electrode? A: Welding electrodes whose coating contains a large amount of acidic oxides, such as the AC/DC welding electrodes E4303 (J422) and E5003 (J502). Q11 What is an alkaline welding electrode? A: Welding electrodes whose coating contains a large amount of basic oxides as well as fluorides, such as welding electrodes Jie 507 (E5015), Jie 506 (E5016), etc. Q12 What is a cellulosic-type electrode (specifically for downward vertical welding)? A: Welding rods containing a large amount of organic matter, designed specifically for vertical welding in pipe and sheet metal structures. 〈1〉Such as E6010 (equivalent to E4310, J425G) is suitable for root welding, heat welding, and fill welding. 〈2〉E8010 (equivalent to E5511, J555) is suitable for hot welding, filler welding, and overlay welding. Generally, low-hydrogen downward welding electrodes are used for the cover pass ； The weld shape of E7048 (equivalent to J506X) is neat and aesthetically pleasing. Q13 Why must welding rods be dried thoroughly before welding? A: Welding rods often experience a deterioration in their performance due to moisture absorption, which leads to an unstable arc, increased spatter, and an increased likelihood of defects such as pores and cracks. Therefore, the welding rod must be thoroughly dried before use. Generally, the drying temperature for acidic welding electrodes is 150–200°C, with a duration of 1 hour ； The drying temperature for alkaline electrodes is 350–400°C, with a drying time of 1–2 hours. After drying, they should be stored in an insulated box at 100–150°C, and retrieved as needed.