1. What is welding?
A: The process of two or more materials (same or dissimilar), by heating or pressurizing or both, to achieve the combination of atoms to form a permanent connection is called welding.

2. What is arc?
Answer: Supply by the welding power source, which produces a strong and lasting gas discharge phenomenon between the two poles - called arc.
<1> According to the type of current, it can be divided into: AC arc, DC arc and pulse arc. <2> According to the state of the arc, it can be divided into: free arc and compression arc (such as plasma arc).
<3> According to the electrode material, it can be divided into: melting electrode arc and non-melting electrode arc.

3. What is the base material?
Answer: The metal being welded is called the base metal.

4. What is a droplet?
Answer: The tip of the welding wire is heated and melted, and the liquid metal droplets that transition to the molten pool are called droplets.

5. What is molten pool?
Answer: The liquid metal part with a certain geometric shape formed on the weldment during fusion welding is called the molten pool.

6. What is a weld?
Answer: The joint formed in the weldment after welding.

7. What is weld metal?
Answer: The part of the metal formed by the solidification of the molten base metal and filler metal (welding wire, electrode, etc.).

8. What is protective gas?
Answer: The protective gas used to protect the metal droplets and the molten pool from the intrusion of harmful gases (hydrogen, oxygen, nitrogen) in welding.

9. What is welding technology?
Answer: The general term for various welding methods, welding materials, welding processes and welding equipment and their basic theories is called welding technology.

10. What is the welding process? What does it contain?
A: A set of process procedures and technical regulations in the welding process. The contents include: welding methods, pre-welding preparation, assembly, welding materials, welding equipment, welding sequence, welding operations, welding process parameters, and post-weld treatment.

11. What is CO2 welding?
Answer: MIG/MAG welding using CO2 with purity > 99.98% as shielding gas - called CO2 welding.

12. What is MAG welding?
Answer: MIG welding with mixed gas 75--95% Ar + 25--5 % CO2, (standard ratio: 80% Ar + 20% CO2) as shielding gas - called MAG welding.

13. What is MIG welding?
Answer: <1> Use high-purity argon Ar ≥ 99.99% as the shielding gas to weld non-ferrous metals such as aluminum and aluminum alloys, copper and copper alloys;
<2> The process method of welding solid stainless steel wire with 98% Ar + 2% O2 or 95% Ar + 5% CO2 as shielding gas - called MIG welding.
<3> Gas-shielded MIG welding with helium + argon inert gas mixture.

14. What is TIG (argon tungsten arc welding) welding?
Answer: Inert gas shielded arc welding using pure tungsten or activated tungsten (thorium tungsten, cerium tungsten, zirconium tungsten, lanthanum tungsten) as the non-melting electrode, referred to as TIG welding.

15. What is SMAW (electrode arc welding) welding?
Answer: The arc welding method of welding with a hand-operated electrode.

16. What is carbon arc gouging?
A: A surface processing method that uses a carbon rod as an electrode to generate an arc with the workpiece, and uses compressed air (pressure 0.5-0.7Mpa) to blow off the molten metal. It is often used for root cleaning of welds, planing grooves, repairing defects, etc.

17. Why is CO2 welding more efficient than electrode arc welding?
Answer <1> CO2 welding has 1-3 times higher melting speed and melting coefficient than electrode arc welding; <2> Groove section is 50% smaller than that of electrode, and the amount of deposited metal is reduced by 1/2; <3> The auxiliary time is the electrode 50% of arc welding.
The total of three items: the ergonomics of CO2 welding is 2.02--3.88 times higher than that of electrode arc welding

18. Why is the quality of CO2 welding joints better than that of electrode arc welding?
Answer: The CO2 weld has a small heat-affected zone and small welding deformation; the CO2 weld has low hydrogen content (≤1.6ML/100g), and the porosity and crack tendency are small; the CO2 weld is well formed, with few surface and internal defects, and the qualified rate of flaw detection higher than electrode arc welding.

19. Why is the overall cost of CO2 welding lower than that of electrode arc welding?
Answer: <1> The cross-sectional area of the groove is reduced by 36-54%, saving the amount of filler metal;
<2> Reduce power consumption by 65.4%;
<3> The equipment shift fee is 67-80% lower than that of electrode arc welding, and the cost is reduced by 20-40%;
<4> Reduce labor costs and working hours, and reduce costs by 10-16%;
<5> Save auxiliary man-hours, auxiliary material consumption and correction of deformation costs;
Combining the five items, CO2 welding can reduce the total welding cost by 39.6-78.7%, with an average reduction of 59%.
 
20. Why does CO2 welding have spatter?
Answer: The droplet at the end of the welding wire is in short-circuit contact with the molten pool (short-circuit transition), and the droplet bursts due to strong overheating and magnetic shrinkage, resulting in splashes. The output reactor and waveform control of the CO2 welder can reduce spatter to a minimum.