Basic knowledge of the hottest welding Q & A 2

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Basic welding Knowledge Q & a

1 What is welding

answer: the process that two or more materials (the same or different) are heated or pressurized or both are used to achieve the combination between atoms and form a permanent connection is called welding

2. What is an arc

answer: it is supplied by the welding power supply and 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 base metal

answer: the metal to be welded is called base metal

4. What is a droplet

answer: the liquid metal drops that melt after heating at the tip of the welding wire and transfer to the molten pool are called molten drops

5. What is a molten pool

answer: the liquid metal part with certain geometry formed on the weldment during fusion welding is called the molten pool

6. What is a weld

answer: the bonding part formed in the weldment after welding

7. What is weld? This journal will introduce the recent cooperation cases between ofo and BASF, Moby and Dow Chemical

answer: the part of metal formed after solidification of molten base metal and filler metal (welding wire, welding rod, etc.)

8. What is protective gas

answer: the gas used to protect metal droplets and molten pool from external harmful gases (hydrogen, oxygen, nitrogen) during welding --- protective gas

9. What is welding technology

answer: all kinds of welding methods, welding materials, welding processes, welding equipment and their basic theories are called welding technology

10. What is welding process? What is it

answer: a whole set of process procedures and technical regulations after mixing plastic and wood powder in a certain proportion during the welding process. The contents include: welding method, preparation and processing before welding, assembly, welding materials, welding equipment, welding sequence, welding operation, welding process parameters, post welding treatment, etc

11. What is CO2 welding

answer: use CO2 with purity> 99.98% as the shielding gas for MIG welding - called CO2 welding

12. What is MAG welding

answer: the mixed gas 75--95% Ar + 25--5% CO2 (standard ratio: 80%ar + 20%co2) is used as the shielding gas for MIG welding, which is called MAG welding

13. What is MIG welding

answer: < 1) use high-purity argon ar ≥ 99.99% as the protective gas to weld non-ferrous metals such as aluminum and aluminum alloys, copper and copper alloys

< 2 > the process method of MIG welding solid stainless steel wire with 98% Ar + 2%o2 or 95%ar + 5%co2 as shielding gas is called MIG welding

<3> MIG welding with helium + argon inert gas mixture as protection

14. What is TIG welding

answer: inert gas shielded arc welding with pure tungsten or activated tungsten (thorium tungsten, cerium tungsten, zirconium tungsten, lanthanum tungsten) as non melting electrode, referred to as TIG welding

15. What is SMAW welding

answer: it is an electric arc welding method that manually operates the welding rod for welding

16. What is carbon arc gouging

answer: it is a surface processing method that uses carbon rod as electrode, generates electric arc with workpiece, and uses compressed air (pressure 0.5-0.7mpa) to blow away molten metal. It is commonly used for weld back gouging, groove planing, defect repair, etc

17. Why is CO2 welding more efficient than electrode arc welding

answer: < 1 > the melting rate and melting coefficient of CO2 welding are times higher than that of shielded metal arc welding

<2> the groove section is reduced by 50% compared with the welding rod, and the amount of deposited metal is reduced by 1/2

<3> the auxiliary time is 50% of the welding rod arc welding

total of three items: the work efficiency of CO2 welding is 2.02--3.88 times higher than that of electrode arc welding

18 Why is the quality of CO2 welded joint better than that of electrode arc welding

answer: CO2 weld has small heat affected zone and small welding deformation; CO2 weld has low hydrogen content (≤ 1.6ml/100g) and small tendency of pores and cracks; CO2 weld is well formed, with few surface and internal defects, and the qualified rate of flaw detection is higher than that of electrode arc welding

19. Why is the comprehensive cost of CO2 welding lower than that of electrode arc welding

answer: < 1 > the groove cross-sectional area is reduced by%, saving the amount of filler metal

<2> reduce power consumption by 65.4%

< 3 > the equipment shift cost is% lower than that of shielded metal arc welding, and the cost is% lower

<4> reduce labor cost and man hour cost, and reduce cost by%

<5) save auxiliary working hours, auxiliary material consumption and deformation correction costs

comprehensive five items, CO2 welding can reduce the total welding cost by 39 7%, the average s=0.002mm decreased by 59%

20. What is low frequency pulse? Which welding is applicable

answer: pulse arc with pulse frequency of 0.5-30hz is called low-frequency pulse welding. It is mainly used for TIG welding of stainless steel, steel, titanium and other non-ferrous metals

21. What is intermediate frequency pulse? Which welding is applicable

answer: the pulse arc with the pulse frequency of Hz is called intermediate frequency pulse welding. Due to its arc compression effect, concentrated arc and good stiffness, it is mainly used for TIG welding of non-ferrous metals such as stainless steel, steel and titanium, and MIG welding of stainless steel, aluminum and aluminum alloys

22. Why does CO2 welding splash

answer: the droplet at the end of the welding wire is in short-circuit contact with the molten pool (short-circuit transition). Due to the strong overheating and magnetic contraction, the droplet bursts and splashes. The output reactor and waveform control of CO2 welding machine can reduce splash to a minimum

23. Why can mig/mag high current welding achieve jet transfer and no spatter

answer: during mig/mag welding, various metals have the critical current value for short-circuit transition to jet transition (such as: φ Customers don't know how to select models 2 carbon steel and stainless steel welding wires, current I ≥ 260-280a), at this time, the arc is in jet transition state, realizing no spatter welding

24. Why does mig/mag low current welding need pulsed power supply to realize jet transfer and no spatter? Answer: for mig/mag welding, when the welding current is lower than the critical current value, the pulsed power supply is used. The pulsed current is greater than the critical current value, and the arc can also be in the jet transition state to realize splash free welding (for example, Panasonic ag2/ge2 pulsed mig/mag welding machine is used, φ 1.2 carbon steel, stainless steel, aluminum and aluminum alloy welding wires have realized pulse droplet transfer when the current is I ≥ 80A, and the pulse current IP ≥ 350A). (end)

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