1. What is welding?
Answer: Two or more materials (the same or different), by heating or pressurizing or both, to achieve the combination between atoms and form a permanent connection process called welding.
2. What is the welding process? What does it have?
Answer: A set of technological procedures and technical regulations in the welding process. The content includes: welding method, pre-welding preparation processing, assembly, welding materials, welding equipment, welding sequence, welding operation, welding process parameters and post-welding treatment.
3. What is welding technology?
Answer: A variety of welding methods, welding materials, welding technology and welding equipment and other basic theory of the general term-called welding technology.
4. What kinds of welding methods are there for electric welding (manual welding)?
Answer: Manual welding is manual arc welding. It is a manual welding method that uses arc as a heat source to melt the welding rod and the base metal to form a weld. According to the manual arc welding process standard, it mainly includes four welding methods: flat welding, vertical welding, horizontal welding and overhead welding.
5. What is co2 welding?
Answer: co2 with purity> 99.98% is used for MIG welding of shielding gas-called co2 welding.
6. What is a welding power source?
Answer: In the electric welding machine, the equipment that supplies the electric energy required for welding and has the electrical characteristics suitable for welding is called welding power supply.
7. Why are there special requirements for arc welding power supplies? What are the requirements?
Answer: In order to ensure the stable combustion of welding arc and adapt to various welding process requirements, arc welding power supply has the following special requirements:
<1> The static characteristics (or external characteristics) of the arc welding power supply, that is, the relationship between the steady-state output current and the output voltage, has a drop characteristic (constant current characteristic) and a flat characteristic (constant voltage characteristic).
A. The external characteristics of electrode arc welding, TIG welding and carbon arc gouging power supply are falling (constant current) characteristics;
B. The external characteristics of CO2/MAG/MIG arc welding power supply are flat characteristics (constant voltage characteristics).
<2> dynamic characteristics of arc welding power supply-when the load state changes instantaneously (e. g. short-circuit transition of molten droplets, particle transition, jet transition, etc.), the relationship between the output current and output voltage of arc welding power supply and time is used to characterize the response capability (I. e. dynamic response capability) to load transients, referred to as "dynamic response capability"
characteristics ".
<3> No-load voltage-the voltage displayed by the power supply before arc ignition.
<4> adjust the characteristics-change the external characteristics of the power supply to meet the requirements of the welding specification.
8. What is arc?
Answer: The welding power supply produces a strong and lasting gas discharge phenomenon between the two poles-called arc.
<1> according to the type of current can be divided into: AC arc, DC arc and pulse arc.
According to the state of the arc, it can be divided into free arc and compressed arc (such as plasma arc).
<3> according to the electrode material can be divided into: melting pole arc and not melting pole arc.
9. Why does the arc voltage change when the arc length changes?
Answer: determined by the external characteristics of the arc welding power supply, the longer the arc, the higher the arc voltage; the shorter the arc, the lower the arc voltage.
10. What is arc stiffness?
Answer: The degree to which the arc straightens along the axial direction of the electrode under the effects of thermal contraction and magnetic contraction.
11. What is arc spot welding?
Answer: For thin plate lap joints, TIG/MIG/MAG/CO2 welding method is used, a certain welding current is used, and a surface nugget is formed within a set time to connect the upper and lower plates.
12. What is the parent material?
Answer: The metal to be welded is called the base metal.
13. What is a droplet?
Answer: The liquid metal drop that melts at the tip of the welding wire and transitions to the molten pool is called a molten drop.
14. What is a molten pool?
Answer: The liquid metal part with a certain geometric shape formed on the weldment during welding is called the molten pool.
15. What is a weld?
A: The joint part formed in the weldment after welding.
16. What is weld metal?
A: The part of the metal formed by the solidification of the molten base metal and filler metal (welding wire, electrode, etc.).
17. What is the protective gas?
Answer: The gas used to protect the metal droplets and the molten pool from the intrusion of harmful gases (hydrogen, oxygen and nitrogen) in welding-the protective gas.
18. What is mag welding?
Answer: mixed gas 75-95% ar +25-5% co2 (standard ratio: 80% ar + 20% co2) is used for shielded gas welding-called mag welding.
19. What is mig welding?
Answer: <1> non-ferrous metals such as aluminum and aluminum alloy, copper and copper alloy are welded under the protection of melting electrode gas with high purity argon ar≥ 99.99 as shielding gas; <2> the process method of welding solid stainless steel welding wire with 98% ar + 2% o2 or 95% ar + 5% co2 as shielding gas is called mig welding. <3> Melt gas shielded welding with helium + argon inert gas mixture.
20. What is tig (argon tungsten arc welding) welding?
Answer: Inert gas shielded arc welding with pure tungsten or activated tungsten (thorium tungsten, cerium tungsten, zirconium tungsten, lanthanum tungsten) as a non-melting electrode, referred to as tig welding.
21. What is SMAW (electrode arc welding) welding?
Answer: The arc welding method of welding with a manually operated electrode.
22. What is carbon arc gouging?
Answer: The use of carbon rod as an electrode, and the workpiece between the arc, with compressed air (pressure 0.5-0.7mpa) will be molten metal blowing away a surface processing method. Commonly used for weld root cleaning, groove gouging, repair defects, etc.
23. Why is co2 welding more efficient than electrode arc welding?
Answer: <1> co2 welding is 1-3 times higher than welding rod arc welding melting speed and melting coefficient;
<2> groove section is reduced by 50% compared with electrode, and the amount of deposited metal is reduced by 1/2;
<3> The auxiliary time is 50% of the electrode arc welding.
Total of the three items: the work efficiency of co2 welding is 2.02-3.88 times higher than that of electrode arc welding.