Exercises. Steel is a ferrous material with some carbon content

STEEL

Steel is a ferrous material with some carbon content. There are two kinds of steel: carbon and alloy steel. The content of carbon in steel may vary from 0.1 to 1.0 per cent. Carbon steel should contain only iron and carbon without any other alloying elements and is divided into:

(1) Machine steel with a low carbon content from 0.05 to 0.15 per cent

(2) Medium carbon steel with a carbon content from 0.15 to 0.60 per cent

(3) Tool steel with a high carbon content from 0.6 to 1.50 per cent Carbon steels are the most common steels used in industry, their properties depending only on the percentage of carbon they contain. Machine steels are very soft and can be used for making machine parts that do not need strength. Medium carbon steels are better grade and stronger than machine steels. Tool steel may be used for manufacturing tools and working parts of machines because of its high strength and hardness.

Alloy steels are those in which in addition to carbon an alloying element is present in some appreciable quantity. They are divided into special alloy steels and high-speed steels which, in turn, are called "self-hardening steels". Alloying elements of these steels are: nickel, chromium, manganese, molybdenum, tungsten, vanadium, etc. These alloying elements have a. definite effect on the characteristic of the steel; nickel increases its strength and hardness; a high percentage of chromium makes steel rust-resistant and in this case it is called "stainless steel". The addition of some tungsten and molybdenum gives heat-resistant steel.Vanadium makes steel corrosion, shock and vibration-resistant. The sand used for making moulds for steel castings differs greatly from that used in other branches of moulding. It must be much more refractory and open grained¹, because the metal is poured at an extremely high temperature and solidifies very rapidly. If the sand is not refractory enough, it will fuse with the metal. The sand being not open grained, the gases will not escape from the mould rapidly enough, and blowholes will be formed in the casting. Many good steel castings are obtained with green sand moulds. Sand moulds are made by shaping the moulding sand around a pattern which is to have the same shape as the finished object, but their size should be a little larger as the steel casting shrinks while cooling. Moulding sand is to be mixed with water in a certain proportion. Many of the smaller steel castings are used as they come from the moulds, but most of the larger ones have to be annealed to relieve the cooling strains formed when the metal solidifies. Steel can be used for a great variety of castings, and it can be cast into very large bodies.

Cast steel parts enter into the make-up² of railroad equipment, agricultural machinery, and many other products where great strength is required. The tensile strength of steel castings is from 55,000 to 70,000 lbs. per square inch. Alloy steel castings are coming into more general use with each year, and they are

influencing the manufacturing methods. It has been found possible to cast with this alloy some shapes that formerly were necessarily made in other ways. It is used in castings where the greatest strength is needed. Much research is being done to improve not only its strength, but also its wearing qualities. Castings are now produced that have a tensile strength from 70,000 to 150,000 lbs. per square inch, the strength depending upon the composition of the alloy and the method of heat treatment.

1. It must be much more refractory and open grained – он должен быть ещё более огнестойким и крупнозернистым

2. make-up – состав

I. Use the following words and phrases in sentences of your own:

to rust, alloying elements, to resist, to escape, stainless steel, carbon steel, machine steel, alloy steel, to fuse, corrosion, refractory, rust-resistant steel, heat-resistant steel, green sand moulds, pattern, strain

II. Answer the following questions:

1. What is steel? 2. What are the main types of steel depending on the carbon content? 3. What steels are most widely used in industry? 4. What manufacturing purposes may tool steel be used for? 5. What is alloy steel? 6. What alloying elements can change the properties of alloy steel0 7. What sand is used for making steel castings? 8. Why must the pattern be a little larger than the casting which is to be produced? 9. What does the tensile strength of steel depend on?

III. Find in the text verbs for the following nouns:

division, casting, difference, fusion, solidification, improvement, requirement, production

IV. Translate the following sentences into Russian and observe the different ways of expressing obligation:

1. Steel has to be widely used in machine-building because of its high strength. 2. Alloy steel must be made by adding some alloying elements. 3. Tools made of high-speed steel may do the work at much higher speeds than carbon tool steels. 4. Chromium and tungsten are to increase the hardness and strength of steel. 5. High carbon steel should be hardened by heating it to a certain temperature and then quickly cooling in water. 6. Special alloy steels can be used for parts requiring great wear resistance.

V. Connect the following sentences Absolute Participle Constructions and translate the sentences into Russian:

Example: 1. Steel is one of the strongest metals.

We use steel for products where great Strength is required

Steel being one of the strongest metals, we useit for products where great strength is required. – Так как сталь является одним изсамыхпрочных металлов, мы используем её для производства изделий, которые требуют большую прочность.

2. Alloying elements for making steel are nickel, chromium, manganese, etc. Nickel increases strength and hardness of the steel. Alloying elements for making steel are nickel, chromium, manganese, nickel increasing strength and hardness of the steel. –Сплавляемыми элементами производства стали являются никель, хром, магнезии и другие, причём никель увеличивает прочность и твердость стали.

1. Alloy steels are ever wider used in industry. Manufacturing methods are changed. 2. The metal is poured at an extremely high temperature. The sand used for making moulds for steel castings should be refractory. 3. Steel is a very strong material. We find wide application of steel in engineering. 4. Heat-resistant steel is made by adding some tungsten and molybdenum. Manganese increases the wear resistance. 5. Steel and cast iron differ in carbon content. The carbon content of steel is little, while that of cast iron is much greater. 6. Some alloying elements make steel rust-resistant. Such steels are called stainless steels.

VI. Underline the suffixes and translate into Russian the following groups of words:

Strong, strength; addition; appreciable, appreciation; de fine, definite, definition; form, formation, former, formerly; vibrate, vibration, vibrator, vibratory

VII. (a) Read and translate the following text without using a dictionary:

PRODUCTION OF STEEL

Converter steel is made from molten pig iron by forcing a blast of cold air under great pressure through the metal. The converter represents a large tank made of steel and covered with refractory bricks with an open top through which the molten metal is poured into the converter and out of it. When forcing the blast of cold air through the melted metal, the oxygen contained in the air combines with the carbon of the pig iron, and almost all the carbon in the metal is turned out. Steel made by this method is very cheap, but it is low grade steel because this method of producing steel cannot be well controlled.

Steel made in this way is called "Bessemer steel". One ton of such steel can be made in one minute.

(b) On the basis of the text make up three questions and answer them

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