We impart strength and toughness to the steel wire at the same time in consideration of the performance (e.g., spring set, workability) of the spring as the final product. Although strength and toughness (ductility / tenacity) generally conflict, this is an important process that requires techniques and know-how in order to balance the two. It is called oil tempered wire after the process by which the steel wire is hardened by quenching with oil etc., prior to being tempered with heat.
The springs used in automobile engines are called valve springs. Such springs and spring materials require extremely high precision and reliability, as broken springs could lead to an engine failure accident. Valve springs must be able to operate at speeds of approximately 1,000 compressions per minute and are subject to the stress of 100 million or more cycles for a vehicle traveling 100,000km. Therefore, more than anything, they require excellent fatigue resistance.
Material defects are one of the major factors affecting the fatigue resistance of springs. Typical examples of this are flaws on the surface of the material and nonmetallic inclusions within the steel itself. These defects can cause not only breakage during spring processing but also fatigue failure after springs are mounted in an automobile engine. Valve spring materials, therefore, need to be free of defects throughout their entire length.
The steel wire used for valve springs is different from general spring material. A special steelmaking method is applied to minimize nonmetallic inclusion in the manufacturing stage, and steel billets are subject to strict flaw assessment. They are then hot rolled from billets into rods, from which the wire will be produced. During this stage, processing flaws may occur, but since this rolling is performed at speeds of 200km per hour or more, it is extremely difficult to detect and locate fine flaws. In the subsequent wire forming process, therefore, the steel wire material for valve springs is shaved or peeled to completely remove surface defects and thereby assure superior reliability.
With the motorization of the 1960s, high-strength materials were applied to valve spring materials, but they were susceptible to flaws, and there were problems with reliability. We initially removed flaws by rotary grinder grinding in order to solve this problem, but flaw removal was not sufficient and comparable grinding marks were produced with this method. Therefore, we developed an in-house shaving technology using an inverted die to completely remove the peel since 1955.
This shaving technology had already been used to remove impurities accumulated on the surface during casting of non-ferrous materials, in particular, copper alloys, and was beginning to apply to aluminum wires, but steels are harder than non-ferrous materials. Therefore, this application was extremely difficult and was not put to practical use. However, continuous researches on shaving dies and equipment had been succeeded in practical use. As a result, it became possible industrially to remove surface defects that affect the fatigue characteristics of springs.
It is no exaggeration to say that the current automobile engine is supported by shaving technology. Moreover, this technology has been used not only for high-strength spring materials but also for removing surface flaws of stainless steel wire for cold workability.
According to the World Steel Association, some of the largest steel-producing countries are China, India, Japan, and the U.S. China accounts for roughly 50% of this production. The world's largest steel producers include ArcelorMittal, ChinaBaowu Group, Nippon Steel Corporation, and HBIS Group.
Methods for manufacturing steel have evolved significantly since industrial production began in the late 19th century. Modern methods, however, are still based on the same premise as the original Bessemer Process, which uses oxygen to lower the carbon content in iron.
Today, steel production makes use of recycled materials as well as traditional raw materials, such as iron ore, coal, and limestone. Two processes, basic oxygen steelmaking (BOS) and electric arc furnaces (EAF), account for virtually all steel production.
Ironmaking, the first step in making steel, involves the raw inputs of iron ore, coke, and lime being melted in a blast furnace. The resulting molten ironalso referred to as hot metalstill contains 4-4.5% carbon and other impurities that make it brittle.
Primary steelmaking has two methods: BOS (Basic Oxygen Furnace) and the more modern EAF (Electric Arc Furnace) methods. The BOS method adds recycled scrap steel to the molten iron in a converter. At high temperatures, oxygen is blown through the metal, which reduces the carbon content to between 0-1.5%.
Secondary steelmaking involves treating the molten steel produced from both BOS and EAF routes to adjust the steel composition. This is done by adding or removing certain elements and/or manipulating the temperature and production environment. Depending on the types of steel required, the following secondary steelmaking processes can be used:
Continuous casting sees the molten steel castinto a cooled mold, causing a thin steel shell to solidify. The shell strand is withdrawn using guided rolls, then it's fully cooled and solidified. Next, the strand is cut depending on applicationslabs for flat products (plate and strip), blooms for sections (beams), billets for long products (wires), or thin strips.
In primary forming, the steel that is cast is then formed into various shapes, often by hot rolling, a process that eliminates cast defects and achieves the required shape and surface quality. Hot rolled products are divided into flat products, long products, seamless tubes, and specialty products.
iron processing, use of a smelting process to turn the ore into a form from which products can be fashioned. Included in this article also is a discussion of the mining of iron and of its preparation for smelting.
Iron (Fe) is a relatively dense metal with a silvery white appearance and distinctive magnetic properties. It constitutes 5 percent by weight of the Earths crust, and it is the fourth most abundant element after oxygen, silicon, and aluminum. It melts at a temperature of 1,538 C (2,800 F).
Iron is allotropicthat is, it exists in different forms. Its crystal structure is either body-centred cubic (bcc) or face-centred cubic (fcc), depending on the temperature. In both crystallographic modifications, the basic configuration is a cube with iron atoms located at the corners. There is an extra atom in the centre of each cube in the bcc modification and in the centre of each face in the fcc. At room temperature, pure iron has a bcc structure referred to as alpha-ferrite; this persists until the temperature is raised to 912 C (1,674 F), when it transforms into an fcc arrangement known as austenite. With further heating, austenite remains until the temperature reaches 1,394 C (2,541 F), at which point the bcc structure reappears. This form of iron, called delta-ferrite, remains until the melting point is reached.
The pure metal is malleable and can be easily shaped by hammering, but apart from specialized electrical applications it is rarely used without adding other elements to improve its properties. Mostly it appears in iron-carbon alloys such as steels, which contain between 0.003 and about 2 percent carbon (the majority lying in the range of 0.01 to 1.2 percent), and cast irons with 2 to 4 percent carbon. At the carbon contents typical of steels, iron carbide (Fe3C), also known as cementite, is formed; this leads to the formation of pearlite, which in a microscope can be seen to consist of alternate laths of alpha-ferrite and cementite. Cementite is harder and stronger than ferrite but is much less malleable, so that vastly differing mechanical properties are obtained by varying the amount of carbon. At the higher carbon contents typical of cast irons, carbon may separate out as either cementite or graphite, depending on the manufacturing conditions. Again, a wide range of properties is obtained. This versatility of iron-carbon alloys leads to their widespread use in engineering and explains why iron is by far the most important of all the industrial metals.
There is evidence that meteorites were used as a source of iron before 3000 bc, but extraction of the metal from ores dates from about 2000 bc. Production seems to have started in the copper-producing regions of Anatolia and Persia, where the use of iron compounds as fluxes to assist in melting may have accidentally caused metallic iron to accumulate on the bottoms of copper smelting furnaces. When iron making was properly established, two types of furnace came into use. Bowl furnaces were constructed by digging a small hole in the ground and arranging for air from a bellows to be introduced through a pipe or tuyere. Stone-built shaft furnaces, on the other hand, relied on natural draft, although they too sometimes used tuyeres. In both cases, smelting involved creating a bed of red-hot charcoal to which iron ore mixed with more charcoal was added. Chemical reduction of the ore then occurred, but, since primitive furnaces were incapable of reaching temperatures higher than 1,150 C (2,100 F), the normal product was a solid lump of metal known as a bloom. This may have weighed up to 5 kilograms (11 pounds) and consisted of almost pure iron with some entrapped slag and pieces of charcoal. The manufacture of iron artifacts then required a shaping operation, which involved heating blooms in a fire and hammering the red-hot metal to produce the desired objects. Iron made in this way is known as wrought iron. Sometimes too much charcoal seems to have been used, and iron-carbon alloys, which have lower melting points and can be cast into simple shapes, were made unintentionally. The applications of this cast iron were limited because of its brittleness, and in the early Iron Age only the Chinese seem to have exploited it. Elsewhere, wrought iron was the preferred material.
Although the Romans built furnaces with a pit into which slag could be run off, little change in iron-making methods occurred until medieval times. By the 15th century, many bloomeries used low shaft furnaces with water power to drive the bellows, and the bloom, which might weigh over 100 kilograms, was extracted through the top of the shaft. The final version of this kind of bloomery hearth was the Catalan forge, which survived in Spain until the 19th century. Another design, the high bloomery furnace, had a taller shaft and evolved into the 3-metre- (10-foot-) high Stckofen, which produced blooms so large they had to be removed through a front opening in the furnace.
The blast furnace appeared in Europe in the 15th century when it was realized that cast iron could be used to make one-piece guns with good pressure-retaining properties, but whether its introduction was due to Chinese influence or was an independent development is unknown. At first, the differences between a blast furnace and a Stckofen were slight. Both had square cross sections, and the main changes required for blast-furnace operation were an increase in the ratio of charcoal to ore in the charge and a taphole for the removal of liquid iron. The product of the blast furnace became known as pig iron from the method of casting, which involved running the liquid into a main channel connected at right angles to a number of shorter channels. The whole arrangement resembled a sow suckling her litter, and so the lengths of solid iron from the shorter channels were known as pigs.
Despite the military demand for cast iron, most civil applications required malleable iron, which until then had been made directly in a bloomery. The arrival of blast furnaces, however, opened up an alternative manufacturing route; this involved converting cast iron to wrought iron by a process known as fining. Pieces of cast iron were placed on a finery hearth, on which charcoal was being burned with a plentiful supply of air, so that carbon in the iron was removed by oxidation, leaving semisolid malleable iron behind. From the 15th century on, this two-stage process gradually replaced direct iron making, which nevertheless survived into the 19th century.
By the middle of the 16th century, blast furnaces were being operated more or less continuously in southeastern England. Increased iron production led to a scarcity of wood for charcoal and to its subsequent replacement by coal in the form of cokea discovery that is usually credited to Abraham Darby in 1709. Because the higher strength of coke enabled it to support a bigger charge, much larger furnaces became possible, and weekly outputs of 5 to 10 tons of pig iron were achieved.
Next, the advent of the steam engine to drive blowing cylinders meant that the blast furnace could be provided with more air. This created the potential problem that pig iron production would far exceed the capacity of the finery process. Accelerating the conversion of pig iron to malleable iron was attempted by a number of inventors, but the most successful was the Englishman Henry Cort, who patented his puddling furnace in 1784. Cort used a coal-fired reverberatory furnace to melt a charge of pig iron to which iron oxide was added to make a slag. Agitating the resultant puddle of metal caused carbon to be removed by oxidation (together with silicon, phosphorus, and manganese). As a result, the melting point of the metal rose so that it became semisolid, although the slag remained quite fluid. The metal was then formed into balls and freed from as much slag as possible before being removed from the furnace and squeezed in a hammer. For a short time, puddling furnaces were able to provide enough iron to meet the demands for machinery, but once again blast-furnace capacity raced ahead as a result of the Scotsman James Beaumont Nielsens invention in 1828 of the hot-blast stove for preheating blast air and the realization that a round furnace performed better than a square one.
The eventual decline in the use of wrought iron was brought about by a series of inventions that allowed furnaces to operate at temperatures high enough to melt iron. It was then possible to produce steel, which is a superior material. First, in 1856, Henry Bessemer patented his converter process for blowing air through molten pig iron, and in 1861 William Siemens took out a patent for his regenerative open-hearth furnace. In 1879 Sidney Gilchrist Thomas and Percy Gilchrist adapted the Bessemer converter for use with phosphoric pig iron; as a result, the basic Bessemer, or Thomas, process was widely adopted on the continent of Europe, where high-phosphorus iron ores were abundant. For about 100 years, the open-hearth and Bessemer-based processes were jointly responsible for most of the steel that was made, before they were replaced by the basic oxygen and electric-arc furnaces.
Apart from the injection of part of the fuel through tuyeres, the blast furnace has employed the same operating principles since the early 19th century. Furnace size has increased markedly, however, and one large modern furnace can supply a steelmaking plant with up to 10,000 tons of liquid iron per day.
Throughout the 20th century, many new iron-making processes were proposed, but it was not until the 1950s that potential substitutes for the blast furnace emerged. Direct reduction, in which iron ores are reduced at temperatures below the metals melting point, had its origin in such experiments as the Wiberg-Soderfors process introduced in Sweden in 1952 and the HyL process introduced in Mexico in 1957. Few of these techniques survived, and those that did were extensively modified. Another alternative iron-making method, smelting reduction, had its forerunners in the electric furnaces used to make liquid iron in Sweden and Norway in the 1920s. The technique grew to include methods based on oxygen steelmaking converters using coal as a source of additional energy, and in the 1980s it became the focus of extensive research and development activity in Europe, Japan, and the United States.
Best Quality TMT Barspass through series of processes that determines the strength & flexibility of it. The manufacturing process of TMT Bar involves series of processes like rolling, water quenching, heat treatment, cooling at various stages of manufacturing.
The iron ore experiences beneficiation procedure to raise the iron substance. At this point metal fines are gathered to shape a mass of pellets and sinter to improve efficiency. The coal is changed to coke for future purpose.
Now limestone accompanies with the existing are deployed to the furnace. Hot air being supplied to the furnace through its nozzle that results melting the raw materials and come out from a pool that is on the bottom of the furnace. In this process when limestone molts a liquid because of its impurity comes out that is knows as slag it is lighter in nature that is why it floats on the surface of the molten metal.
Now molten steel from EAF (Electric Arc Furnace) is transferred to a ladle and it transferred to the continuous casting machine. Liquid steel flows out of the ladle into the casting ladle and then into water cooled mold.
Quenching Once the hot rolled bars releases from finished mill it enters to the water spray system that is known as Thermex System. The best quality tmt bars manufacturing process uses Thermex Technology that cool down the outer core rapidly and ensure the ductility of TMT Rebars. Rapid cooling hardens the outer core of the TMT Rebars to a depth optimized for each section, forming a martensitic rim while the core remains hot & Austenitic.
Self Tempering Once the rebars is out of the Thermex Quenching box, the core remains hot compared to the surface allowing heat to flow from the core to the surface causing Tempering of the outer Martensite layer thus forming a structure called Tempered Martensite.
Atmospheric Cooling Once the self tempering is over the bars get ready for atmospheric cooling. This is done on cooling bed on normal temperature. In this step the austenitic core turns as ferrite-pearlite structure. Thus the final structure consists of strong outer layer with ductile core. This process increases the tensile strength that makes it highly ductile and weldable.
Best TMT Barsare always manufactured atIntegrated Steel Plantswhere as explained in this topic starting from manufacturing the raw material till its ending everything is done under one roof. Shyam Steel Industries Ltd is a reputed TMT Bar manufacturer in India since 1953. For our continuous quality control and unmatched after sales support it is proudly associated with Indias Largest Construction Projects.
Shyam Steel has best quality steel manufacturing Integrated Steel Plants located in West Bengal. Our state-of-the-art Integrated steel plant includes manufacturing setup like DRI Unit, EAF, Continuous Billet Casting Mill, sophisticated and high-speed Rolling Mill, microprocessor-based product technologies and fully-equipped Quality Assurance & Testing laboratories. Our Best Quality TMT Bar is most preferred for all type of construction purposes across India.
Best TMT Bar Manufacturing Plants India In the Direct Reduced Iron (DRI) plant, production of sponge iron using a solid reductant involves reducing iron ore (lumps/pellets) with a carbonaceous material such as coal. The reduction is carried out in a rotary kiln (which is inclined and rotates at a predetermined range of speeds) at a stipulated temperature (8500C 10500C). The inclination and the rotary motion of the kiln ensure that the raw materials move from the feed end to the discharge end of the kiln and during this movement the actual reduction of iron ore to iron takes place. The material discharged from the kiln is taken to a rotary cooler for cooling and the cooled product is separated from the coal char.
Melting is accomplished by injecting energy to the charge materials in the form of electrical energy through three numbers graphite electrodes. Carbon injected inside the furnace reacts with oxygen producing CO, which bubbles through the bath creating foamy slag. The excess CO reacts with oxygen, converting to CO2, again generating heat. Oxygen will react with several components present in the bath including silicon; manganese; phosphorus and sulphur. The oxides thus formed will end up in the slag. In arc furnace charged materials get melted at about 1800C.
Once sufficient charge has been melted and enough space has been created, the second charge can be taken and the process is repeated. Once the final charge has been melted and is reached at melt stage, Temperature measurement is taken and the sample is drawn for determining the amount of oxygen to be blown during refining.
Phosphorus and sulphur which cannot be removed from Induction Furnace can be easily removed in EAF. Phosphorous is removed in the early stage of refining. Sulphur is removed as sulphides in slag and is better achieved during the reducing stage.
Aluminum, silicon, and manganese react with oxygen before carbon to form oxides which go into the slag. CO, which is produced due to the reaction of carbon with oxygen, bubbles through the bath causing the slag to foam and has many beneficial effects. The foaming also helps in bringing down nitrogen and hydrogen levels in steel. At the end of the refining stage temperature measurement is done and the sample is drawn for analysis.
The furnace is tilted towards the slag door for slag removal. Phosphorus is transferred to the slag, during the early stage of the heating while the temperature is relatively low. The first de-slagging (at the beginning of refining) removes the substantial portion of the phosphorous (as P2O5) thus preventing phosphorous reversal to the metal. Typically during the refining state, the furnace may be de-slagged several times.
After reaching the required temperature and composition, the tap hole is opened and metal is tapped into the ladle and sent to continuous casting unit for the casting of billets, during the tapping process bulk alloys are based on the bath analysis for the desired steel grade. De-oxiders may be added to the steel to control the oxygen content, prior to further processing. This is commonly referred to as killing of steel. This is done by adding aluminum or silicon in the form of ferrosilicon or silicon manganese.
Molten Steel from EAF is tapped into a laddle and taken to the continuous casting machine. Liquid steel flows out of the laddle into the tundish and then into water-cooled mold. Solidification begins in the mold. The continuous Billets coming out from the CCM is sized according to the length required.
The billets manufactured are re-heated at a temp of 1200C in the re-heating furnace and rolled into specific sections of finished material in the Rolling Mill Unit. In the case of manufacturingTMT Re-bars, from the finishing stand of the rolling Mill, the Re-Bars are guided through a specially designed propriety Thermex pipes to obtain special property Thermax Process as explained below:
The hot rolled bar from the finished mill stand enters into the Thermex System and is rapidly cooled by a special water spray system. This rapid cooling hardens the surface of the TMT Re-bars to a depth optimized for each section, forming a martensitic rim while the core remains hot and & Austenitic. This rapid cooling is called quenching.
After Re-bars leave the quenching box, the core remains hot compared to the surface allowing heat to flow from the core to the surface causing Tempering of the outer Martensite layer thus forming a structure called Tempered Martensite.
This takes place on the cooling bed, where the Austenitic core is transformed into ductile Ferrite-Perlite structure. Thus the final structure consist of stronger outer layer (Tempered Mastensite) with ductile core (Ferrite-Pearlite). This process increases the tensile strength of the material while keeping high ductile and weldability. Best TMT Bar Manufacturing Plants India This whole process is a patented technology from HSE, Germany under the brand name of Thermex.
Wrought iron is a specific type of iron alloy with very low carbon content in contrast to cast iron. Wrought iron furniture and different home decor items are very popular nowadays. In addition, wrought iron furniture is the best choice for patio furniture. Wrought iron is amazingly durable and sturdy and can resist even the harshest of weather. Another important aspect of choosing wrought iron type furniture is that it is incredibly versatile.
Powder-coated wrought iron furniture comes with different modern and innovative designs and models. Any individual can start a small-scale wrought iron furniture-making business with moderate capital investment. Here in this article, we intend to explore how to start a wrought iron furniture manufacturing business in India.
Nowadays, this specific type of furniture is gaining tremendous popularity. Not only in metro cities but also suburban and small towns are the big market. The longevity of this product is also more and the product remains elegant and beautiful for a long time. Moreover, this furniture can carry any weight and size and cannot be destroyed easily.
With the increasing population, there are growing numbers of educational institutes, hospitals, hotels, commercial establishments and offices in the country. And they are widely using chairs, tables, sofas, beds, cabinets, cupboards, dressing tables, etc. This is also popular as the patio or outdoor furniture.
Due to some specific advantages,wrought iron furniture is fast replacing conventional wooden items. Apart from the domestic market, there is also anexport market for quality wrought iron furniture. Europe and America are the major markets for export from India.
This is a small scale manufacturing business. In addition, the business demands different types of registration and licensing. It is advisable to check your state laws. Here we put some of thebasic requirements.
A 200 Sq Mt area is sufficient for small scale operation. However, you must provide specific spaces for raw material storage, production area, painting zone, finished goods storage and space for official work. In addition, you will need to arrange utilities like electricity and water. It is advisable to start with a rental premise. However, it is always better to have a place in an industrial zone. It will ensure the availability of cheap and easy access to labour and transport.
Select the machinery carefully. Furthermore, you will find a lot of technically upgraded tools in the market. Ask the machine supplying company for arranging theon-site product demonstration. Moreover, procure tools and equipment as per your desiredquality and output demand.
You can procureplenty of raw material of wrought iron in the shape of round, square, iron rods, square pipes and also in other sectional forms from the market. First of all, you will need to craft the design. Then cut thesheets, strips, and tubular wrought iron to the required sizes. Then press toshapebent in a press brake for sides and drawers.
Generally, the backs of chairs, sofas, and beds consist of decorative designing of various kinds of flowers and leaves, etc. You can make these designs with the pressing machine from the strips. Then do welding the sides and backs of wrought iron furniture. In addition, you can make the holes by drilling. Finally, spray paint gives an amazing and glossy black look.
You can procure the raw materials from the local wholesale market. However, procuring wrought iron materials from the manufacturer ensures better pricing. Tap the local market first. In addition, you can grow your wrought iron manufacturing business by expanding areas and distribution channels.