Utilization of high strength steels

There are obvious advantages in using high strength steels for applications where pay load increase, dead weight reduction are of prime concern. There are also many instances of low ambient temperature applications where heat-treated high strength steels are needed.

Besides the economical advantage of getting more strength per pound of steel, use of high strength steels offers other advantages to the designer. For one thing, it permits designs that would otherwise not be practical, such as long-span parallel-chord trusses and uniform depth girders. It simplifies overall design and makes these structures less complicated. Although fabrication may be more involved by use of several different types of steel; overall fabrication generally is simpler because members are lighter and consist of fewer pieces. Because these structures are simpler, streamlined and less complicated, they are also more pleasant to look at and are worthy examples of the builder’s art. There are a few pitfalls that must be avoided when designing with high strength steels and there must be a thorough understanding of these steels. A structure is designed against failure in one or more modes. Buckling and excessive deflection are functions of the modulus of elasticity and must be guarded against by use of low slenderness ratios and high moments of inertia. Fatigue often controls the design of structures. When stress concentrations are involved, such as at welds, fatigue strength doesn’t necessarily increase in proportion to yield or tensile strength of the steel. Thus designers need to consider the ways in which high strength steels can be disposed in a structure to greatest advantage. Notch toughness, is an important factor in selecting steel for a structure subject to brittle fracture. Many of the high strength steels possess a high degree of notch toughness and are actually less apt to fail in a brittle manner than some lower strength steels. However, higher design stresses demand greater notch toughness.

Task 1

Give Ukrainian equivalent to the following words and word combinations.

manufactured, rolled sheets, strip, satisfactorily, seam welding, drawing, prime factor, tempered carbon steels, rectangular tubular products, designed,obvious advantages, heat-treated high strength steels, long-span parallel-chord trusses, streamlined, pitfalls, buckling, excessive deflection, notch toughness, brittle fracture.

Task 2

Match the following words with their translation:

1. welding	a) опір, стійкість
2. reduction	b) жорсткість, в’язкість
3. resistance	c) втомленість
4. fatigue	d) пружність, гнучкість
5. strength	e) зварювання
6. toughness	f) відхилення, прогинання, провис
7. deflection	g) міцність
8. elasticity	h) зменшення

Task 3

Fill in the correct words from the list below. Use each word only once:

tubular, loss, parallel-chord, art, ratios, ambient,

sheets, obvious, yield, originally, prime, structures

1. a … factor	7. low … temperature applications
2. hot rolled …	8. … advantages
3. round … products	9. … are simpler
4. were … furnished	10. minimum … in ductility
5. builder's …	11. low slenderness …
6. long-span … trusses	12. minimum … strength

Task 4

Fill in the gaps with the verbs given below used in the proper tense form.

to offer, to furnish, to become, to provide,

to simplify, to dispose, to enhance, to avoid

1. The use of high strength steels ____ overall design and makes these structures less complicated.

2. Molybdenum, manganese, and a grain refiner ____ the strength of these steels with minimum loss in ductility and toughness.

3. These steels originally ____ as hot rolled sheets and strip.

4. There are a few pitfalls that ____ when designing with high strength steels.

5. Besides the economical advantage of getting more strength per pound of steel, use of high strength steels ____ other advantages to the designer.

6. Designers need to consider the ways in which high strength steels ____ in a structure to greatest advantage.

7. High strength carbon steels ____ available in plate and structures aswell as in sheets.

8. High strength steels ____ higher strength than hot rolled steels.

Task 5

Fill in the gaps with the verbs given below used in the proper tense form.

The early steels developed were classified as copper-nickel-phosphorus and chromium-silicon-copper. These elements improved corrosion resistance. Other elements, such as molybdenum and manganese enhanced their strength with minimum loss in ductility and toughness.

These steels were manufactured to 12 maximum carbon and were originally furnished as hot rolled sheets and strip. They are welded very satisfactorily, even by spot and seam welding, and could be fabricated by bending and moderate drawing. Development of these steels enjoyed such success that demand soon arose for carbon steels to meet the same strength levels where corrosion resistance was not a prime factor. High-strength low-alloy and high strength carbon steels became available in plate and structures aswell as in sheets. Some hot rolled steels containing columbium or vanadium are available up to 65,000 psi yield strength. Further research and development have now produced weldable, quenched and tempered carbon steels with minimum yield strengths up to 80,000 psi and quenched and tempered low alloy steels with 100,000 psi minimum yield strength. These steels not only provide higher strength than the hot rolled steels, but improve toughness at low temperatures.

Round and rectangular tubular products as well as plates and bars are available at these strength levels.

furnish	представлять, предоставлять, снабжать
enjoy	насолоджуватися, користуватися, наслаждаться, пользоваться, обладать, получать удовольствие
structure	структура, строение, состав, сооружение, устройство, здание, профиль, схема, текстура
plate	пластинка, тарелка, табличка, лист, анод, фотопластинка, печатная форма, листовая сталь, гравюра, столовое серебро, вклейка, полоса, номер автомобиля, эстамп, гальваноклише, металлическая посуда, мауэрлат, груз, вставная челюсть, стереотип, скачки на приз, призовой кубок, тарелка для сбора пожертвований, дощечка с фамилией, иллюстрация на отдельном листе
sheet	лист, листок, ведомость, таблица, слой, простыня, страница, пласт, шкот, пелена, газета, чехол, парус, плоскость, печатный лист, пластина коллектора, тонколистовая сталь, тонколистовое железо, язык, язык пламени, обширная поверхность, широкая полоса
toughness	міцність, заможність, цупкість, пружність
payload	корисне навантаження
dead weight	дедвейт, собственный вес, мертвый вес, бремя, полная грузоподъемность
ambient	навколишній, навкружний, що оточує з усіх боків
dispose	располагать, ликвидировать, размещать, склонять, расставлять, предопределять, определять
notch	выемка, надрез, метка, паз, вырезка, вырез, уровень, зазубрина, зарубка, бороздка, углубление, зубец, желобок, щель, ущелье, прорез, пропил, засечка, степень, теснина, горный перевал, впадина, нарезка, царапина, утор, подрез
apt	придатний, схильний, здібний, підхожий, виразний, доречний, емоційний, зручний, імовірний, можливий, сприйнятливий
chord	связка
trusses	ферми
girder	балка
overall	загальний
streamlined	обтічний, добре налагоджений обтекаемый, модернизированный хорошо налаженный удобообтекаемый
pitfalls	пастки
buckling	викривлення, короблення, жолоблення потеря устойчивости коробление прогиб перекашивание кручение
slenderness ratio	гибкость
moment of inertia	момент инерции

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Дата добавления: 2015-07-20