The Complete Technology Book On Hot Rolling Of Steel Pdf Catalog
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The hot rolling technology is the most widely used method of shaping metals and is particularly important in the manufacture of steel for use in construction and other industries.
In metalworking, rolling is a metal forming process in which metal stock is passed through a pair of rolls. Rolling is classified according to the temperature of the metal rolled. If the temperature of the metal is above its re crystallization temperature, then the process is termed as hot rolling. The hot mills using plain rolls were already being employed by the end of the seventeenth century.
But the industrial revolution in the nineteenth century saw a new horizon in steel making process, with the considerably expanded markets for rods, rails and structural section, provided further impetus to the development of hot rolling. The basic use of hot rolling mills is to shape up the larger pieces of billets and slabs into narrow and desired forms.
These metal pieces are heated over their re crystallization temperature and are then moved between the rollers so as to form thinner cross sections. Hot rolling mill thus helps in reducing the size of a metal thereby molding it into the desired form and shape. Rolling mills perform the function to reform the metal pieces such as billet and ingot whilst maintaining its well equipped micro structure into bar, wire, sheet, strip, and plate. Hot rolled products are frequently categorized into plain carbon, alloy, high strength alloy, dual phase, electrical and stainless steels.
This book provides a descriptive illustration of pre treatment of hot metal, the basic principles of heat treatment, types of hot rolled products, principles of measurement of rolling parameters, steel making refractories, performance characteristics of transducers, causes of gauge variation , main factors affecting gauge performance, gauge control sensors and actuators, automatic gauge control systems, strip tension control system in cold mills, flat rolling practice cold rolling, pack rolling, steelmaking refractories, refining of stainless steels, special considerations in refining stainless steels etc.
This book is a unique compilation and it draws together in a single source technical principles of steel making by hot rolling process up to the finished product.
This handbook will be very helpful to its readers who are just beginners in this field and will also find useful for upcoming entrepreneurs, engineers, personnel responsible for the operation of hot rolling mills, existing industries, technologist, technical institution etc.
Hot-rolled products are frequently categorized into plain-carbon, alloy, high-strength low-alloy HSLA , dual-phase, electrical, and stainless steels.
Although distinctly different in their physical and metallurgical properties, particularly at elevated temperatures, these various products must generally be rolled on the same hot-rolling mills since it would not be economic to provide separate facilities for the different steels. However, as will be seen in later chapters, the rolling operations must be carried out under somewhat different conditions for the various products, particularly with respect to mill drafting and finishing temperatures.
In the early stages of hot rolling, the ingots or continuously cast strands are converted into a variety of semi-finished and finished products.
The former are differentiated on the basis of geometrical shape, such as slabs, blooms and billets, and the latter on the basis of the products shipped, such as plates, hot-rolled strip and rods.
Until recently, two or more hot mills may have been necessary to impart the final dimensions to the workpiece. For example, ingots would be rolled first on a slabbing mill and the slabs would be later reheated and rolled to plates on another mill.
However, with the advent of the continuous casting of steel, this situation is changing and semi-finished products that were once rolled, such as slabs and billets, may now be continuously cast and sized by in-line rolling stands. As the name implies, plain-carbon steels, representing the most important group of engineering materials known, consist essentially of iron alloyed with carbon. For carbon contents less than 0. Hypoeutectoid steels are further classified as low-carbon carbon contents less than 0.
Plain-carbon steels always contain low concentrations of manganese, silicon, phosphorus and sulphur, as well as minor amounts of other elements. As an example, a steel will contain 0. Free-cutting rephosphori-zed and resulphurized, and resulphurized carbon-steel compositions used for these applications may contain significant amounts of phosphorus and sulphur.
For example, a steel should contain no more than 0. Plain-carbon steels may also be classified in accordance with their method of manufacture, such as basic open-hearth, acid open-hearth, basic oxygen, basic electric furnace and Q-BOP steels. At the same time, the method of deoxidation may also be used for categorization, as exemplified by rimmed, capped, semi-killed,or fully-killed steels.
Further-more, since the widespread use of continuous-casting machines, a distinction is often made between ingot and continuously cast "conticast" steels. Generally speaking, plain-carbon steels are hot rolled when their temperature corresponds to the austenitic range. As a consequence, the deformation achieves considerable homogenization which tends to eliminate dendritic segrega-tion by a breakup of the dendritic structure. During the deformation process, recrystallization occurs so that the final austenitic grain size is determined by the temperature of the workpiece during the last rolling pass.
Lastly, the dendrites and the inclusions are reoriented in the rolling direction so that ductility in this direction is markedly improved.
Although most carbon steels are used without a final heat treatment, such a step may be used to improve the microstructure and properties for specific applications.
With respect to rolled products, heat treatments include annealing, normalizing, quenching and tempering, and austempering.
To satisfy an increasing demand for carbon steels having hardenability characteristics that are required for a wide variety of heat-treated parts, boron is frequently used as an alloying element in such steels. Very small quantities of boron as little as 0. In addition to carbon, manganese, phosphorus, sulphur, and silicon, some of the other elements present in minute quantities include hydrogen, oxygen, and nitrogen introduced during the steelmaking process, nickel, copper, molybdenum, chromium, and tin present in the steelmaking scrap and aluminum, titanium, vanadium, and zirconium introduced during deoxidation of the steel.
Nitrogen plays a role in the aging of the steel and also exerts a strengthening effect on the material. Hydrogen causes embrittlement or low ductility but will gradually diffuse out of small sections even at room temperature. It also causes flaking, manifested by internals cracks or bursts, a condition which may be minimized by slow cooling after forging or rolling as is now the standard practice in the manufacture of rails. The elements nickel, chromium, molybdenum and copper tend to increase the hardenability of carbon steels and may be important where deep-drawing characteristics are to be obtained after annealing.
Tin, in relatively small amounts also adversely affects deep-drawing properties. On the other hand, aluminum acts as a grain refiner and decreases the susceptibility of the steel to strain aging. However, it tends to promote graphitization and is therefore undesirable in steels to be used for high-temperature applications.
The remaining two deoxidizers, titanium and zirconium, are usually present in such small concentrations as to exert a negligible effect on the properties of the steels. Alloy steels, which may contain up to approximately 50 percent of alloying elements, are defined as those steels which possess enhanced properties due to the presence of one or more special elements or to the presence of larger concentrations of elements, such as manganese and silicon, than would be ordinarily present in plain-carbon steels.
The major classification of steels containing alloying elements are as follows: 1 SAE-AISI alloy, 2 high-strength low-alloy, 3 dual-phase, 4 electrical or silicon, 5 stainless and 6 alloy tool steels. In addition, steels are often categorized as heat-resisting if they are suitable for elevated-temperature service. However, this group of steels really includes those found within some of the other categories. According to the American Iron and Steel Institute AISI , the definition of an alloy steel is as follows: "By common custom, steel is considered to be an alloy steel when the maximum of the range given for the content of alloying elements exceeds one or more of the following limits: manganese, 1.
In addition, the following elements are considered incidental when their concentrations fall below the levels indicated: copper, 0. The first digit indicates the type of steel with the second digit signifying the percentage of the predominating alloying element. The last two digits usually indicate the average carbon content in "points" or hundredths of a percent.
Table -1 summarizes the effects of the various alloying elements. Once referred to as high-tensile steels or low-alloy steels, high-strength low-alloy steels exhibit yield points in excess of 40, psi.
They contain small amounts of alloying elements and achieve their strength in the hot-rolled or normalized conditions. It is to be noted that the minimum yield strength for these materials ranges from 42, to 80, psi within certain thickness limitations. These steels are available as sheet, strip, bars and shapes and are generally sold as proprietary products. However, for prolonged service life, HSLA steels must have adequate corrosion resistance.
Accordingly, compositions have been developed for such materials which exhibit four to to eight times the atmospheric corrosion resistance of structural carbon steel. Other properties which must be displayed by HSLA steels include good formability as measured by bend tests, tensile elongation and fabrication performance , good weldability, good toughness under adverse conditions particularly low temperatures , good fatigue resistance and good abrasion resistance.
Since HSLA steels possess ferrite-pearlite microstructures, their properties are determined basically by the fineness of the structure mainly the ferrite and by dispersed phases or dislocations in the ferrite.
In addition to microstructural effects, certain alloying elements provide solid-solution strengthening of the ferrite. With respect to the effects of the various alloying elements, they are as follows: Carbon, which significantly enhances pearlite formation, is one of the more effective and economical strengthening elements.
Manganese has a similar effect to carbon but to a lesser extent. However, it improves notch toughness and slightly enhances corrosion resistance. Phosphorus increases the strength of HSLA steels by entering into solid solution in the ferrite but, at the same time, it decreases ductility but improves corrosion resistance. However, this element is by far the most potent of all the common alloying elements in improving atmospheric corrosion resistance.
Vanadium, a widely used alloying element in HSLA steels, strengthens by precipitation hardening of the ferrite and by refining the ferrite grain size. The use of niobium as a strengthening element began in the early 's, the element significantly increasing the yield point and, to a lesser extent, the tensile strength of the steel, in a manner similar to that of vanadium. However, the notch toughness is adversely affected unless special rolling practices are used which involve lower-than-normal finishing temperatures or accelerated cooling after hot-rolling.
Nitrogen is used in light-gage products to increase strength, particularly in vanadium-containing HSLA steels, due to precipitation hardening. Nickel provides a moderate increase in strength by solution hardening and a slight increase in notch toughness. Silicon provides only a slight increase in strength due to ferrite hardening and chromium provides both strengthening and improved atmospheric corrosion resistance.
Titanium exhibits effects similar to those contributed by vanadium and niobium but, because of its strong deoxidizing characteristics, is used only in fully killed steels. Lastly, zirconium is added to killed HSLA steels to modify the inclusions and improve trans verse bend properties. Dual-phase low-alloy steels are low-carbon steels that have been micro-alloyed yith small amounts of elements such as vanadium, niobium or titanium, and are characterized by a microstructure exhibiting islands of a hard martensitic phase in a matrix of softer ferrite.
Technically, this structure consists of ferrite and from 5 to 50 percent martensite or lower bainite usually around 20 percent. As an example of composition, one heat-treatable grade contains 0. When initially deformed, such steels behave very much like a low-strength steel in the range of 50, to 65, psi yield strength but, because of workhardening in succeeding forming operations, the final part will possess the high yield strength typical of 80, to , psi steels.
This is due to the fact that deformation increases the yield strength at a rate of about psi for each 0. The structure of a DPLA steel can be developed by either of two ways: by heat treatment after rolling or directly through conventional hot-rolling processes.
In the former case, the steel is heated to a critical temperature within the alpha-gamma region of the phase diagram for a specific time and then quenched. Ideally, for economic reasons, this thermal treatment should coincide with standard mill annealing cycles but, at the present time, the mill must be slowed down or the steel chemistry must be adjusted to accelerate the dual-phase transformation.
On the other hand, when the properties are to be developed in the course of hot rolling, the hot-rolled strip is coiled in the transformation gap as illustrated in Figure Hansen-and Bramfitt have found that, with respect to a Generation I hot strip mill: 1 the mechanical properties achieved off the mill are comparable with those of as-annealed dual-phase steels although the hot-rolled product differs structurally in being an aggregate of ferrite, martensite and granular bainite, 2 the optimum composi-tion contained 1.
Increasing the carbon content produces increased amounts of martensite and granular bainite, the result being significantly higher tensile strengths and reduced ductility. The fatigue strength of certain grades of DPLA steels is often higher than carbon steel and weldability is stated to be as good as AISI aluminum-killed carbon steel. Low-temperature toughness and ductile-to-brittle transition temperatures are comparable with those of low-carbon steels.
These steels are iron-silicon alloys with an upper limit of about 5 per cent silicon. There are a number of grades of electrical sheets in each of the above categories. Other oriented grades less frequently used include the M-3, M-7, M-8 and M-9 types.
Core losses of some of these materials are as presented. The steelmaking operations for the oriented grades are closely controlled to ensure the cleanest and purest steel possible. The alloying addition of ferrosilicon is made in the ladle and the pouring practices are much like those used for other fully killed steels with the ingots being hot-rolled to slabs by ordinary practices.
Astm Standards Pdf. Drawing and Drafting. Our workmanship standards allow for no more than 0. It is done by spraying salt on a specimen housed in a closed chamber. Welded and Seamless Pipes. ASTM A 3. Find the ASTM hardness standards referincing guide her.
An investigation on the roll force and torque fluctuations during Keywords hot rolling process, finite element method, roll force, roll torque, aluminum alloysit will be possible to increase the production speed of the cold strip mill. Roll Mill Torque Speed Curves Ball Mill Vfd Motor torque speed curves ball mill vfd motor starting torque of ball mill calculation rolling mill torque calculation. Calculates the rolled length of a roll of material when the outside diameter of the material, thickness of the material, and the diameter of the hole in the center or the tube on which the material is wound are given. Variations due to stretching or softness of the material are to be ignored. An example of rolled material would be a rolled carpet or a rolled sheet of paper from the paper mill. How can I calculate the force required to bend a 10 mm thick plate. ABB strip tension load cells in processing lines.
Steel Estimate Pdf
ASTM's steel standards are instrumental in classifying, evaluating, and specifying the material, chemical, mechanical, and metallurgical properties of the different types of steels, which are primarily used in the production of mechanical components, industrial parts, and construction elements, as well as other accessories related to them. The steels can be of the carbon, structural, stainless, ferritic, austenitic, and alloy types. These steel standards are helpful in guiding metallurgical laboratories and refineries, product manufacturers, and other end-users of steel and its variants in their proper processing and application procedures to ensure quality towards safe use. Additive Manufacturing Standards. Cement Standards and Concrete Standards.
The concept is similar to the rolling of dough.
In This Guide You’ll Learn
The hot rolling technology is the most widely used method of shaping metals and is particularly important in the manufacture of steel for use in construction and other industries. In metalworking, rolling is a metal forming process in which metal stock is passed through a pair of rolls. Rolling is classified according to the temperature of the metal rolled. If the temperature of the metal is above its re crystallization temperature, then the process is termed as hot rolling. The hot mills using plain rolls were already being employed by the end of the seventeenth century.
Veinte minutos, - сказал .
Это означало, что на его, Халохота, стороне фактор внезапности, хотя вряд ли он в этом так уж нуждается, у него и так все козыри на руках. Ему на руку была даже конструкция башни: лестница выходила на видовую площадку с юго-западной стороны, и Халохот мог стрелять напрямую с любой точки, не оставляя Беккеру возможности оказаться у него за спиной, В довершение всего Халохот двигался от темноты к свету. Расстрельная камера, мысленно усмехнулся. Халохот оценил расстояние до входа.
Во рту у него был фонарик в виде авторучки, в руке - паяльник, а на животе лежала большая схема компьютера. Он только что установил новый комплект аттенюаторов на неисправную материнскую плату, когда внезапно ожил его мобильный. - Проклятие! - выругался он, потянувшись к телефону сквозь сплетение проводов. - Джабба слушает.
Ей в голову пришла и другая мысль - известно ли Хейлу, что Танкадо уже нет в живых. Сьюзан стала быстро закрывать файлы электронной почты Хейла, уничтожая следы своего посещения. Хейл ничего не должен заподозрить -. Ключ к Цифровой крепости, внезапно осенило ее, прячется где-то в глубинах этого компьютера.
Она посмотрела на вентиляционный люк и принюхалась. Но запах шел не оттуда, его источник находился где-то поблизости. Сьюзан посмотрела на решетчатую дверь, ведущую в кухню, и в тот же миг поняла, что означает этот запах. Запах одеколона и пота. Она инстинктивно отпрянула назад, застигнутая врасплох тем, что увидела.
Он с трудом сдержал улыбку. - Только лишь мошонка. Офицер гордо кивнул: - Да. Когда церковь получит все останки этого великого человека, она причислит его к лику святых и разместит отдельные части его тела в разных соборах, чтобы все могли проникнуться их величием. - А у вас здесь… - Беккер не сдержал смешка.
- Я должен выполнять свои обязанности. Он поднял телефонную трубку и набрал номер круглосуточно включенного мобильника Джаббы. ГЛАВА 45 Дэвид Беккер бесцельно брел по авенида дель Сид, тщетно пытаясь собраться с мыслями.
Это сложнейшая работа, заключающаяся в постоянном отсеивании лишнего, но она вполне выполнима. Сьюзан понимала, что, по всей логике, именно ей предстояло решить эту задачу.
Внешняя окружность была затуманена и казалась почти прозрачной. - У нас имеется пять уровней защиты, - объяснял Джабба. - Главный бастион, два набора пакетных фильтров для Протокола передачи файлов, Х-одиннадцать, туннельный блок и, наконец, окно авторизации справа от проекта Трюфель. Внешний щит, исчезающий на наших глазах, - открытый главный компьютер. Этот щит практически взломан.
Нам нужен этот шифр-убийца, или все здесь провалится сквозь землю. Все стояли не шелохнувшись. - Да вы просто с ума все сошли, что ли? - закричал Джабба. - Звоните Танкадо.
Не упустите. Даже клочка бумаги. - Где теперь это кольцо? - спросил Беккер. Лейтенант глубоко затянулся. - Долгая история.
Но Танкадо… - размышляла. - С какой стати такой параноик, как Танкадо, доверился столь ненадежному типу, как Хейл.
На этом Мидж капитулировала: - Хорошо. Доброй ночи. - Она двинулась к двери.
- Скажи первое, что придет в голову. - Ассоциативный ряд? - по-прежнему недоумевал Дэвид. - Стандартная для АНБ процедура.
Хейл внезапно почувствовал беспокойство - скорее всего из-за необычного поведения Сьюзан. Он быстро пересек комнату и преградил ей дорогу, скрестив на груди руки. - Скажи мне, что происходит, - потребовал. - Сегодня здесь все идет кувырком.