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Technical Files
Welding Basics Question and Answer
 

1. What welding materials contain?

A. Welding materials contain covered electrode or electrode rod, welding wire, flux, gas, electrode, pad, etc..

 

2. What is called welding wire?

A. A metal wire which used as welding filler and conductor in the same time of welding is called welding wire. It is divided into two kinds: solid wire and flux cored wire. The commonly used solid wire is Model: ER50-6 (Trademark: H08Mn2SiA).

 

3. Why impact toughness of MAG welding joints is higher than impact toughness of CO2 welding joints?

A. Active gas in MAG welding was only 20%, transition coefficient of alloy elements in welding wire is high, and the result of impact toughness of welding joints is high.

But active gas in CO2 welding was 100%, alloy of manganese and silicon deoxidized together, transition coefficient of alloy elements in welding wire is lower, and the result of impact toughness of welding joints is not so good as MAG. For example, Tangshan Shinko MG-51 welding wire (equivalent ER50-6), the impact toughness at room temperature: MAG: 160J; CO2 : 110J.

 

4. What is the flux cored wire?

A. Round steel pipeline rolled by thin steel strip, while some components of powder filled in it, then drew them to a welding wire.

5. Why it must be used CO2 gas for protection when use the flux cored wire?

A. There two types of flux cored wire: gas protection wire and flux cored itself protection wire. It is commonly used CO2 gas for flux cored wire, this is belonging to gas-residue combinative protection, and can get good form of welding joints, and high-performance integrated machinery.

6. Why there is some impressed holes on the surface of welding joints when it is used flux cored wire?

A. Because flux cored wire is rolled into a pipe with thin steel strip, and it is belonging to a slot welding wire; water in the air will immerse into the flux cored, and the welding powder will wet (no method to dry), so that, it will cause impressed holes.

7. Why the purity of CO2 gas is the technical requirement?

A. CO2 gas is generally chemical product, the purity is only about 99.6%, containing traces of impurities and moisture, it will bring defects such as porosity. When weld important product, it must be used CO2 gas 99.8%, and can get good characteristics: less porosity in welding joints, low hydrogen content, good crack resistance.

 

8. Why there is a high purity argon technical requirement?

A. There are three kinds of argon on the market: General argon (purity about 99.6%), pure argon (purity about 99.9%), special pure argon (purity 99.99%). The first and the second can be welded carbon steel and stainless steel, when weld aluminum and aluminum alloy, titanium and titanium alloy, and so on non-ferrous metals, it must be used special pure argon, in order to avoid the welding joints zone is oxidized, and can not be welded.


9. Why there are several sizes of TIG (Tungsten arc Inert Gas protective welding) welding nozzle?

A. There are five standard nozzles: 48|, it is used 45|when weld carbon steel; used 67|when weld stainless steel, aluminum and aluminum alloy, these sizes are larger in order to reinforce the protective zone of welding joints and heat affected zone. It is used 78|( more larger) when weld titanium and titanium alloy, and so on non-ferrous metals, only this way can prevent the weld and heat affected zone from oxidization.

 

10. What is acidic welding rod?
A. There are several acidic oxides covered on the surface of welding rod, these kinds of welding rod are called acidic welding rod, such as Structure Steel 422 (E4303), Structure Steel 502 (E5003) for use in both AC and DC electrical supply.

 

11. What is alkalescence welding rod?

A. There are several alkalescence fluoride covered on the surface of welding rod, these kinds of welding rod are called alkalescence welding rod, such as Structure Steel 507 (E5015), Structure Steel 506 (E5016), etc..

12. What is called cellulose type (downward vertical welding professional) welding rod?

A. There are large amounts of organic covered on the surface of welding rod, these are used professional for pipeline and thin sheet metals when structure downward vertical welding.

(1) For example E6010 (equivalent to E4310, J425G) applied to backing welding, heat welding, filling welding.

(2) E8010 (equivalent to E5511, J555) applied to heat welding, filling, covered surface layer welding.

Generally use in downward covered surface layer welding rod: when use E7048 (equivalent to J506X), it can obtain a good effect: welding joints appearance clean and beautiful.

 

13. Why the welding rod must be strict drying before use?

A. Because the welding rod is easy effect with damp, this will cause its technical performance bad, the electric arc will instability, splash will increase, and will easy cause holes, cracks and other defects. Therefore, the welding rod must be dried strictly before use. General acidic welding rod drying temperature is at 150~200, and 1 hour; alkalenscene welding rod drying temperature is at 350~400, and 1~2 hours. After drying, put the welding rod into attemperator and keep at 100~150, whenever take to use.

2010-7-17
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