Text 4. Types of welding

Non-consumable electrode are welding

As a non-consumable electrodes tungsten or carbon electrodes can be used. In gas-tungsten arc welding a tungsten electrode is used in place of the metal electrode used in shielded metal-arc welding. A chemically inert gas, such as argon, helium, or carbon dioxide is used to shield the metal from oxidation. The heat from the arc formed between the electrode and the metal melts the edges of the metal. Metal for the weld may be added by placing a bare wire in the arc or the point of the weld. This process can be used with nearly all metals and produced a high-quality weld. However, the rate of welding is considerably slower than in other processes.

Shielded metal are welding

In shielded metal-arc welding, a metallic electrode, which conducts electricity, is coated with flux and connected to the other and of the same source of current. An electric arc is formed by touching the tip of the electrode to the metal and then drawing it away. The intense heat of the arc melts both parts to be welded and the point of the metal electrode, which supplies filler metal for the weld. This process is used mainly for welding steels.

Gas-metal are welding

In gas-metal welding, a bare electrode is shielded from the air by surrounding it with argon or carbon dioxide gas and sometimes by coating the electrode with flux. The electrode is fed into the electric arc, and melts off in droplets that enter the liquid metal of the weld seam. Most metals can be joined by this process.

Submerged are welding

Submerged-arc welding is similar to gas-metal arc welding, but in this process no gas is used to shield the weld. Instead of that, the arc and tip of the wire are submerged beneath a layer of granular, fusible material that covers the weld seam. This process is also called electro slag welding. It is very efficient but can be used only with steels.

Additional vocabulary:

gas-tungsten welding – сварка оплавлением вольфрамовым электродом в среде инертного

газа

inert – инертный

bare – голый

rate – скорость

gas-metal arc – аргонодуговая сварка

surrounding – окружающий

liquid – жидкость, жидкий

droplet – капелька

carbon dioxide – углекислый газ

beneath – под, ноже, внизу

layer – слой

weld seam – сварной шов

semi-automatic – полуавтоматическая

to submerge – погружать

Answer the questions:

1. What is the difference between the arc welding and non-consumable electrode arc welding?

2. What are the disadvantages of the non-consumable electrode arc welding?

3. How is electrode protected from the air in gas-metal arc welding?

4. What is submerged arc welding?

5. What is the principle of resistance welding?

6. Where is semi-automatic welding employed?

Translate into English:

1. вольфрамовый электрод

2. инертный газ

3. окисление

4. высококачественный сварочный шов

5. скорость сварки

6. аргон, гелий, углекислый газ

7. жидкий металл

8. слой плавкого металла в виде гранул

9. листовой металл

10. полуавтоматические сварочные станки

Translate into Russian:

1. In resistance welding, heat is obtained from the resistance of metal to the flow of an electric current.

2. The heat from the arc melts the edges of the metal.

3. A bare electrode is shielded from the arc by surrounding it with argon or carbon dioxide gas.

4. Submerged-arc welding is similar to gas-metal arc welding.

5. Electrodes are clamped on each side of the parts to be welded.

6. Resistance causes heat, which melts the metals and creates the weld.