Technological Processes of Metal Hot Treatment



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Technological Processes of Metal Hot Treatment



 

Engineering is the sphere of activity dealing with various manufacturing processes. It presupposes not only machining the parts and units, but also their industrial production. The manufacturing processes are: casting, welding, forging, pressing, upsetting, rolling, extrusion, stamping, drawing, squeezing. There are basically two types of metal treatment – one that is performed at relatively low temperatures, cold working; and the other performed at high temperatures, hot working

Hot or heat treatment is also called thermal processing of metals and alloys. Properly designed and implemented thermal processing can result in the positive changes in physical, chemical and mechanical properties of materials. All metals can be subjected to thermal processing with the following purposes: improvement in ductility, relieving internal stresses, grain size refinement, increase of strength, improvement in machinability, toughness, etc.

Thermal processes may be broadly classified into two categories based on cooling rates from elevated temperatures – annealing and quenching / tempering. Annealing involves cooling slowly, while quenching means very fast cooling the material using cooling medium like water / oil bath.

Let’s consider hot metal treatment – casting. Metal casting is an ancient technique that has a variety of applications and purposes. The process of metal casting involves melting metals at high temperatures and using molds to further shaping the metal into new items. The furnace used in metal casting is the inalienable part of the process. Metal casting requires specialized equipment, knowledge and creativity. Since metal casting involves working with metal in its molten form, the process can be dangerous. The melting point of several metals is above 1000 degrees Fahrenheit, or 530 degrees Celsius. It is vital that anyone dealing with metal casting should take all the proper precautions and use appropriate safety gear, such as gloves and goggles.

The history of joining metals goes back to several millennia.

Welding is a fabrication process that joins materials, usually metals or thermoplastics, by causing coalescence. This is often done by melting the workpieces and adding a filler material to form a pool of molten material (the weld pool) that cools to become a strong joint. Many different energy sources can be used for welding, including a gas flame, an electric arc, a laser, an electron beam, friction, and ultrasound.

The most common gas welding process is oxyfuel welding, also known as oxyacetylene welding. It is one of the oldest and most versatile welding processing, but less popular in industrial applications. It is still widely used for welding pipes and tubes, as well as repair work.

Arc welding is the process which uses a welding power supply to create and maintain an electric arc between an electrode and the base material to melt metals at the welding point. One of the most common types of arc welding is shielded metal arc welding (SMAW).

Energy beam welding methods, laser beam welding and electron beam welding, are relatively new processes. The two processes are quite similar, differing mostly in the source of power. Laser beam welding employs a highly focused laser beam, while election beam welding is done in a vacuum and uses an electron beam.

Some modern welding methods do not involve the melting of the materials being joined. One of the most popular, ultrasonic welding, is used to connect thin sheets or wires made of metal or thermoplastic by vibrating them at high frequency and under high pressure. The processes commonly used for welding dissimilar materials (aluminum with steel) belong to solid-state welding processes. To such technologies friction welding refers.

Exercise 1. Translate the derivative words with the suffix –ity, -ty into Russian and name the original word:

activity, creativity, property, ductility, machinability, safety, variety.

 

Exercise 2. Translate the word combinations with Participle II into Russian:

information connected with speciality; treatment performed at high temperatures; properly designed processing; properly implemented treatment; thermal process based on cooling rate; treatment based on elevated temperatures; molten form of metal; a pool of molten material; welding known as oxyacetylene welding; shielded welding; a highly focused laser beam; the materials being joined; sheets and wires made of metal; the processes commonly used belong to … .

Exercise 3. Complete the sentences:

1. Engineering is the sphere of activity dealing with …

2. Heat treatment is also called …

3. Properly implemented thermal processing can result in …

4. Thermal processes may be broadly classified into …

5. Annealing involves …

6. The process of quenching means …

7. Working with molten metal can be …

8. The history of joining metals goes back to …

9. Welding is a fabrication process that joins …

10. The most common gas welding process is …

 

Exercise 4. Insert the proper words into the sentences:

1. Engineering (предполагает) not only (обработку деталей) but also their production.

2. There are two temperature types of (металлообработки).

3. (Тепловая обработка) can improve (свойства материалов).

4. (Литье) involves (плавление металла) at high temperatures.

5. (Использование литейных форм) shapes the metal into new items.

6. (Литье металлов) requires specialized (оборудования).

7. (Точка плавления) of several metals is very high.

8. While working with (расплавленным металлом) proper (предосторожности) should be observed.

9. One of the types of (дуговой сварки) is (дуговая сварка в защитной среде).

10. The solid state welding is used for welding (разнородных материалов).

 

Exercise 5. Find English equivalent to the Russian word:

1. сжатие а) pressing c) stamping

b) squeezing d) stressing;

 

2. техника a) machinery c) technics

b) engineering d) technique;

 

3. деятельность a) concern c) activity

b) business d) occupation;

 

4. литье а) melting c) pouring

b) casting d) shaping;

 

5. обработка а) machining c) processing

b) treatment d) turning;

 

6. горячая a) thermal processing c) hot treatment

обработка b) warm processing d) heat treatment;

 

7. расплавленный a) flow metal c) molten metal

металл b) hot metal d) liquid metal;

 

8. универсальный, а) comprehensive c) versatile

всесторонний b) universal d) unique;

9. луч, пучок а) ray c) light

b) beam d) laser.

Exercise 6. Translate into Russian:

 

1. В машиностроении существуют различные способы обработки материалов.

2. Производственными процессами являются: литье, сварка, ковка, штамповка и другие.

3. Различные материалы обрабатываются при разных температурах.

4. Доменная печь является неотъемлемой частью литья материалов.

5. При горячей обработке металлы улучшают такие качества, как ковкость, прочность, обрабатываемость.

6. Горячая обработка металлов включает такие процессы, как отжиг и закалка.

7. В процессе сварки расплавленный металл при охлаждении соединяет детали.

8. Самым старым и универсальным способом сварки является ацетиленокислородная сварка.

9. Энергетическими способами сварки являются лазерная и электронная сварка.

10. Ультразвуковая сварка не требует плавления материала.

Speaking:

Exercise 7. Give the summary of the text, using key vocabulary and tell about:

a) the manufacturing processes;

b) the essence of hot treatment of metals;

c) the varieties of thermal processes;

d) the precautions when working with molten metals;

e) the types of welding.

Checklist for Section VII:

1. How is Participle II translated into Russian in the function of an attribute?

2. What words are formed with the suffixes -ity, -ty?

3. What are metal manufacturing processes?

4. What are the main features of thermal processing?

 

Section VIII



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