Случайная страница | ТОМ-1 | ТОМ-2 | ТОМ-3
АвтомобилиАстрономияБиологияГеографияДом и садДругие языкиДругоеИнформатика
ОбразованиеОхрана трудаПедагогикаПолитикаПравоПсихологияРелигияРиторика

Types of Metals

Читайте также:
  1. Fabrication of metals
  3. Metals and Alloys
  4. Metals in Periodic Table
  6. Read the text consulting the dictionary, be ready to discuss different types of milling machines
  7. Section I. Metals in Periodic Table

All engineering industry is based on processing and application of metals. The selection of material can play very important role in terms of their qualities to prevent failures. Selection of material for a specific purposes depends on many factors. Some of the most important ones are: strength, ease of forming, and resistance to environmental destruction.

Metallic materials are broadly divided into two types – ferrous and non-ferrous ones. Ferrous materials are those in which iron (Fe) is the principle constituent. All other materials are categorized as non-ferrous materials. The main difference between both types of metals is based on their formability.

Ferrous materials are produced in large quantities. One main drawback of ferrous alloys is their environmental destruction, i.e. poor corrosion resistance. Other disadvantages include: relatively high density and comparatively low electrical and thermal conductivities.

Non-ferrous materials have specific advantages over ferrous ones. They can be easily fabricated, have relatively low density, and high electrical and thermal conductivities. However, different materials have distinct characteristics, and are used for specific purposes.

The term “pure metal” is used for materials in which almost all chemical elements, but one are eliminated. The designation “metal” is applied to any metallic materials in which metallic lustre and the ability for plastic deformation being characteristic features.

To ferrous metals belong: pig iron, cast iron, wrought iron, steel and others. Pig iron is the starting material in the production of all ferrous metals. It contains iron as the main ingredient, the impurities being carbon, silicon, manganese, sulphur and phosphorus. Cast iron is the pig iron modified in structure by remelting it with addition of steel scrap. Wrought iron is the iron from which almost all impurities of carbon, sulphur, phosphorus and other have been removed by the process known as puddling. Steel may be shortly defined as an alloy of iron and carbon. The chief alloying elements used being nickel, chromium, molybdenum, silicon, vanadium, tungsten, cobalt and copper.

To non-ferrous metals are referred: gold, silver, aluminium, copper, lead, zinc, mercury, magnesium, titanium, nickel, chromium, molybdenum, vanadium, tungsten, cobalt.

Some of these are the ingredients of cutting-tool materials which must combine strength, toughness, hardness, and wear resistance at elevated temperatures. These requirements are met in varying degrees by carbon steels (containing from 1 to 1,2 per cent of carbon), high-speed steels (iron alloys containing tungsten, chromium, vanadium and carbon), tungsten carbide and aluminium oxide.

Let’s consider one of the mentioned metals – Vanadium. It is the chemical element with the symbol V and atomic number 23. Vanadium was discovered in 1801, but renamed by its modern name in 1831. It is a soft, silvery, grey, ductile transition metal. It has good resistance to corrosion and is stable against alkalis, sulfuric and hydrochloric acids. Vanadium is used in the form of ferrovanadium as an additive to improve steels. The considerable increase of strength in steel containing small amounts of vanadium was the reason for using it for applications in axles, bicycle frames, crankshafts, gear, and other critical components.


Exercise 3. Complete the sentences:

1. The selection of material is important to prevent…

2. Metallic materials are divided into…

3. Iron is the principle constituent in…

4. Beside ferrous materials, all other are categorized as…

5. The main drawback of ferrous alloys is …

6. Different materials have distinct…

7. To ferrous metals belong…

8. Steel may be defined as…

9. To non-ferrous metals are referred…

10. The strength of steel was the reason for…


Exercise 4. Insert the proper words into the sentences:

1. The selection of material is important (с точки зрения) their qualities.

2. One of the most important quality is (сопротивление) to (окружающая среда) destruction.

3. Iron is (главный составляющий) of ferrous materials.

4. The main difference in the types of metals is their (обрабатываемость).

5. One of the drawbacks of ferrous metals is poor (сопротивление к коррозии).

6. The designation “metal” (применяется) to metallic materials with specific (свойствами, характеристиками).

7. Most of the non-ferrous metals are (составная часть) of (режущий) materials.

8. Vanadium has good (сопротивляемость к коррозии и кислотам).

9. Vanadium as (добавка) (улучшать) the (свойства) of steels.

10. The strength of steel is the reason of its (применение) in (коленчатый вал) and (шестерня).

Exercise 5. Find in the text the sentences that correspond to the following statements:

1. The choice of material is very important factor in machinery.

2. Strength, formability and corrosion resistance are the most important features.

3. Iron is the main ingredient of ferrous materials.

4. High density and low conductivity are the drawbacks of ferrous metals.

5. The word “metal” is used referring to metallic materials possessing specific characteristics.

6. Alloying ingredients of steel are the majority of non-ferrous metals.

7. Tools for processing materials should be strong, hard and wear resistant.

8. Carbon steels meet the requirements necessary for cutting- tool materials.

9. Some metals are resistant not only to corrosion but to acids.

10. Many metals are used in parts where strength is needed.


Exercise 6. Translate into English:

1. Машиностроение имеет дело с обработкой различных металлов.

2. Металлы должны обладать такими качествами, как прочность, ковкость, обрабатываемость.

3. Черные и цветные металлы обладают различными свойствами.

4. Недостатком черных металлов является их низкая сопротивляемость коррозии.

5. Цветные металлы имеют низкую плотность и легко обрабатываются.

6. Термин «чистый металл» означает материал, в котором содержится только один элемент.

7. Отличительной чертой металлов является блеск, тягучесть и способность к пластической деформации.

8. К черным металлам относятся чугун, литой чугун, сварочное железо и стали.

9. Элементами сплавов, как правило, являются никель, хром, молибден, ванадий, вольфрам, кобальт и другие.

10. К цветным металлам относятся алюминий, золото, серебро, медь, магний, титан, ртуть и другие.



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

a) division of metallic materials into groups;

b) qualities of ferrous metals;

c) characteristics of non-ferrous metals;

d) what materials can be alloying elements;

e) the role of alloying elements.


Checklist for Section II:

1. What are the Tense forms of Passive Voice?

2. What is the meaning of suffixes –ful and - less?

3. What are ferrous and non-ferrous metals?

4. What are characteristic features of these groups?


Дата добавления: 2015-07-07; просмотров: 197 | Нарушение авторских прав



Читайте в этой же книге: Section I. Metals in Periodic Table | Section IV. Steels | Section V. Fabrication of Metals | Fabrication of metals | Introduction. Machine Tools | Read and translate | Drill Presses | Geared head drill press | Mill drill | Speaking |
<== предыдущая страница | следующая страница ==>
Metals in Periodic Table| Metals and Alloys

mybiblioteka.su - 2015-2023 год. (0.038 сек.)