1. Answer the following questions:

1. What are the most essential features of Gas Metal-Arc Welding? In 3-4 sentences describe this process.

2. What do you know about Electroslag Welding?

2. Give the summary of the text.

3. Fill in prepositions if necessary.

1. Deoxidizers present_______the electrode can completely prevent oxidation_______the weld puddle, making multiple weld layers possible at the joint.

2. _______addition, the temperatures involved in GMAW are relatively low.

3. It has virtually replaced SMAW_______present-day welding operations in manufacturing plants.

4. Electroslag Welding deposits the weld metal______the weld cavity between the two plates to be joined.

5. The weld metal is produced_______a filler wire that forms an initial arc with the workpiece.

6. There are also variations of ESW where shielding is provided_______an appropriate gas.

4. Point out which of these sentences do not contain information from the text. Translate these sentences into Russian:

1. Electroslag Welding (ESW) deposits the weld metal into the weld cavity between the two plates to be joined.

2. In addition, the temperatures involved in GMAW are relatively low and are therefore suitable for thin sheet and sections less than ¼ inch.

3. The process utilized an electron gun similar to that used in an X-ray tube.

4. GMAW may be easily automated, and lends itself readily to robotic methods.

5. Mechanical pumps can produce vacuums to the medium pressure level.

6. Deoxidizers present in the electrode can completely prevent oxidation in the weld puddle, making multiple weld layers possible at the joint.

7. Recent advances in equipment allow the work chamber to operate at a medium vacuum or pressure.

8. The weld metal is produced from a filler wire that forms an initial arc with the workpiece until a sufficient pool of liquid metal is formed to use the electrical resistance of the molten slag.

9. It has virtually replaced SMAW in present-day welding operations in manufacturing plants.

10. Virtually all of the kinetic energy-the energy of motion-of the electrons is transformed into heat upon impact.

5. Translate the following words paying attention to their suffixes.

External, mixtures, completely, layer, relatively, addition, automated, readily, operation, produced, resistance, primarily.

6. Find in the dictionary all possible meanings of these words. Use them in your own sentences.

Complete, mixture, present, involve, suitable, section, plant, shoe, arc, pass, use, initial, space, provide, machine.

Read and translate the text.

Text B

Tin-Lead Solder

The largest portion of all solders in use is solders of the tin-lead alloy group. They have good corrosion resistance and can be used for joining most metals. Their compatibility with soldering processes, cleaning, and most types of flux is excellent.

In describing solders, it is the custom of industry to state the tin content first; for example, a 40/60 solder means to have 40% tin and 60% lead.

Tin-lead alloy melting characteristics depend upon the ratio of tin to lead. The higher the tin content, the lower the melting temperature. Tin also increases the wetting ability and lowers the cracking potential of the solder.

100% lead melts at 327,22°C and 100% tin melts at 232,22°C. Solders that contain 19.5% to 97.5% tin remain a solid until they exceed 182,22°C. The eutectic composition for tin-lead solder is about 63% tin and 37% lead. (“Eutectic” means the point in an alloy system that all the parts melt at the same temperature.) A 63/37 solder becomes completely liquid at 182,78°C. Other compositions do not. Instead, they remain in the pasty stage until the temperature increases to the melting point of the other alloy. For instance, 50/50 solder has a solid temperature of 182,78°C and a liquid temperature range of 213,89°C. The pasty temperature range is 13,33°C – the difference between the solid and the liquid.

Solders with lower tin content are less expensive and primarily used for sheet metal products and other high-volume solder requirements. High tin solders are extensively used in electrical work. Solders with 60% tin or more are called fine solders and are used in instrument soldering where temperatures are critical.

Tin-Antimony-Lead Solder

Antimony is added to a tin-lead solder as a substitute for some of the tin. The antimony, up to 6%, increases the strength and mechanical properties of the solder. A word of caution, solders having a high antimony content should not be used on aluminum, zinc, or zinc-coated materials.

They form an intermetallic compound of zinc and anti-mony that causes the solder to become very brittle.

Tin-Zinc Solder

Several tin-zinc solders have come into use for the joining of aluminum alloys.

The 91/9 and 60/40 tin-zinc solders are for higher tem-perature ranges (above 300°F), and the 80/20 and 70/30 tin-zinc alloys are normally used as precoating solders.