Е. С. Закирова, П. А. Красавин Английский язык для технических вузов
IMPORTANT METAL PROPERTIES FOR MANUFACTURING
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- TEST 7 1. Choose the proper words and fill in the blanks.
| IMPORTANT METAL PROPERTIES FOR MANUFACTURING
One of the most important aspects in manufacturing is to choose the right material for a particular application. There are some important properties of metals: ductility, malleability, elasticity, hardness, durability, etc. Ductility is a solid material ability to be stretched into a wire. Malleability, a similar property, is a material ability to form a thin sheet by hammering or rolling. Both of these mechanical properties are aspects of plasticity, the extent to which a solid material can be plastically deformed without fracture. Ductil- ity and malleability are not always coextensive, for example, while gold is both ductile and malleable, lead is only malleable. Elasticity is an ability of a material to stretch easily and then return to its original shape quickly. Springs are usually made out of elastic materials such as spring steel, titanium, and bronze. Hardness is an ability of a material to resist to various kinds of shape change when a force is applied. Common examples of hard materials are not only certain metals but also ceramics. Hardness of a material affects its dura- bility. Generally, hard metals are more durable than soft ones. The properties of a metal can be changed by heat treating. The main types of heat treating are quenching, annealing, tempering. Quenching is a heat treating process when metal is heated, and then dipped in water or oil to cool it rapidly. It makes metal to be harder but more brittle. While annealing, metal is also heat- ed, but then is allowed to cool slowly. Annealed metal is softer and more elastic. While tempering, metal is heated and kept at high temperature for a period of time. As a result, tempered metal has a balance between hardness and elasticity. TEST 7 1. Choose the proper words and fill in the blanks. 1. Materials which consist of two or more elements combined by chemical reaction present a category of … . 137 A. elements C. mixtures B. compounds D. composite materials 2. … is a matrix with a reinforced material inside it. A. An element C. A mixture B. A compound D. A composite material 3. … includes two or more elements which are not chemically bound. A. An element C. A mixture B. A compound D. A composite material 4. … cannot be broken into separate constituents. A. An element C. A mixture B. A compound D. A composite material 5. Cast iron and steel are … . A. elements C. mixtures B. compounds D. composite materials 6. Copper is … . A. an element C. a mixture B. a compound D. a composite material 7. Polymers are representatives of … . A. ceramics C. non-metallic materials B. plastics D. thermosets 8. … polymers are usually called “plastics”. A. Natural B. Synthetic C. Cheap D. Non-rusting 9. Ceramics are … . A. ductile B. stiff C. malleable D. lightweight 10. A lot of engineering materials are … to engineer. A. flexible B. brittle C. available D. subsequent жүктеу/скачать 4,38 Mb. Достарыңызбен бөлісу:
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