Агабекян учебник для тех.вузов. Агабекян учебник для тех. Агабекян И. П., Коваленко П. И. Английский для технических вузов
 Скачать 357.82 Kb.
|
Text В: «STEEL»The most important metal in industry is iron and its alloy — steel. Steel is an alloy of iron and carbon. It is strong and stiff, but corrodes easily through rusting, although stainless and other special steels resist corro sion. The amount of carbon in a steel influences its prop erties considerably. Steels of low carbon content (mild steels) are quite ductile and are used in the manufacture of sheet iron, wire, and pipes. Medium-carbon steels con taining from 0.2 to 0.4 per cent carbon are tougher and stronger and are used as structural steels. Both mild and medium-carbon steels are suitable for forging and weld ing. High-carbon steels contain from 0.4 to 1.5 per cent carbon, are hard and brittle and are used in cutting tools, surgical instruments, razor blades and springs. Tool steel, also called silver steel, contains about 1 per cent carbon and is strengthened and toughened by quenching and tempering. The inclusion of other elements affects the properties of the steel. Manganese gives extra strength and tough ness. Steel containing 4 per cent silicon is used for trans former cores or electromagnets because it has large grains acting like small magnets. The addition of chro mium gives extra strength and corrosion resistance, so we can get rust-proof steels. Heating in the presence of carbon or nitrogen-rich materials is used to form a hard surface on steel (case-hardening). High-speed steels, which are extremely important in machine-tools, contain chromium and tungsten plus smaller amounts of vana dium, molybdenum and other metals. Vocabulary: alloy — сплав carbon— углерод stiff — жесткий to corrode — разъедать, ржаветь rusty — ржавый stainless — нержавеющий to resist — сопротивляться considerably — значительно, гораздо tough — крепкий, жесткий, прочный, вынос ливый forging — ковка welding — сварка brittle — хрупкий, ломкий cutting tools — режущие инструменты surgical instruments — хирургические ин струменты blade — лезвие spring — пружина inclusion — включение to affect — влиять manganese — марганец silicon — кремний rust-proof — нержавеющий nitrogen — азот tungsten — вольфрам General understanding: 1. What is steel? 2. What are the main properties of steel? 3. What are the drawbacks of steel? 4. What kinds of steel do you know? Where are they used? 5. What gives the addition of manganese, silicon and chromium to steel? 6. What can be made of mild steels (medium-carbon steels, high-carbon steels)? 7. What kind of steels can be forged and welded? 8. How can we get rust-proof (stainless) steel? 9. What is used to form a hard surface on steel? 10. What are high-speed steels alloyed with? Exercise 1.5. Find the following words and word combinations in the text: 1. сплав железа и углерода 2. прочный и жесткий 3. легко коррозирует 4. нержавеющая сталь 5. низкое содержание углерода 6. ковкость 7. листовое железо, проволока, трубы 8. конструкционные стали 9. пригодны для ковки и сварки 10. твердый и хрупкий 11. режущие инструменты 12. хирургические инструменты 13. инструментальная сталь 14.упрочнять 15. добавление марганца (кремния, хрома, вольфра ма, молибдена, ванадия) Text С: «METHODS OF STEEL HEAT TREATMENT»Quenching is a heat treatment when metal at a high temperature is rapidly cooled by immersion in water or oil. Quenching makes steel harder and more brittle, with small grains structure. Tempering is a heat treatment applied to steel and certain alloys. Hardened steel after quenching from a high temperature is too hard and brittle for many appli cations and is also brittle. Tempering, that is re-heating to an intermediate temperature and cooling slowly, re duces this hardness and brittleness. Tempering tempera tures depend on the composition of the steel but are fre quently between 100 and 650 °C. Higher temperatures usually give a softer, tougher product. The color of the oxide film produced on the surface of the heated metal often serves as the indicator of its temperature. Annealing is a heat treatment in which a material at high temperature is cooled slowly. After cooling the metal again becomes malleable and ductile (capable of being bent many times without cracking). All these methods of steel heat treatment are used to obtain steels with certain mechanical properties for certain needs. Vocabulary: to immerse — погружать to apply — применять intermediate — промежуточный oxide film — оксидная пленка annealing — отжиг, отпуск cracking — растрескивание General understanding: 1. What can be done to obtain harder steel? 2. What makes steel more soft and tough? 3. What makes steel more malleable and ductile? 4. What can serve as the indicator of metal tempera ture while heating it? 5. What temperature range is used for tempering? 6. What are the methods of steel heat treatment used for? Exercise 1.6. Translate into English the following words and word combinations: 1. температура нормализации 2. мелкозернистая структура 3. быстрое охлаждение 4. закаленная сталь 5. состав стали 6. окисная пленка 7. индикатор температуры 8. медленное охлаждение FAMOUSPEOPLEOFSCIENCE Dmitry Ivanovich Mendeleyev Dmitry Ivanovich Mendeleyev is a famous Russian chemist. He is best known for his development of the periodic table of the properties of the chemical elements. This table displays that elements' properties are changed periodically when they are arranged according to atomic weight. Mendeleyev was born in 1834 in Tobolsk, Siberia. He studied chemistry at the University of St. Petersburg, and in 1859 he was sent to study at the University of Heidelberg. Mendeleyev returned to St. Petersburg and became Professor of Chemistry at the Technical Insti tute in 1863. He became Professor of General Chemistry at the University of St. Petersburg in 1866. Mendeleyev was a well-known teacher, and, because there was no good textbook in chemistry at that time, he wrote the two-vol ume «Principles of Chemistry» which became a classic textbook in chemistry. In this book Mendeleyev tried to classify the elements according to their chemical properties. In 1869 he pub lished his first version of his periodic table of elements. In 1871 he published an improved version of the peri odic table, in which he left gaps for elements that were not known at that time. His table and theories were proved later when three predicted elements: gallium, germanium, and scandium were discovered. Mendeleyev investigated the chemical theory of solu tion. He found that the best proportion of alcohol and water in vodka is 40%. He also investigated the thermal expansion of liquids and the nature of petroleum. In 1893 he became director of the Bureau of Weights and Measures in St. Petersburg and held this position until his death in 1907. UNIT 2 |