<meta name=”google-site-verification” content=”eN_fLv_JhcmJI2cMQfAiSpshZpRpf_OhWSkOtfXqE04″ />
What is Wrought Iron?
What is wrought iron? During the Middle Ages, water-power was applied to the process, probably initially only for powering bellows, and only later to hammers for forging the blooms. However, while it is certain that water-power was used, the details of this remain uncertain. This was the making. Survived in Spain and southern France as Catalan Forges to the mid 19th century, in Austria as the stuckofen to 1775; near Gars tang in England until about 1770; and was still in use with hot blast in New York State in the 1880s.
Wrought iron is relatively pure, and normally contains less than .15% carbon and other impurities. But the process of its manufacture is laborious and tedious. Following are the four distinct operations involved in its manufacture:
Pig iron is melted and a strong current of air is directed over it. It is thus thoroughly oxidized. Afterward it’s then cast into molds. It is cooled suddenly so as to make it brittle. Refined pig iron is broken into lumps and is melted in the hearth of the reverberate furnace. Hearth lining acts as an oxidizing agent and, in addition, oxidizing substances are added to the refined pig iron. At last It is kept well stirred by long bars through working doors. During the process of puddling, most of the carbon content and other impurities of the pig iron are oxidized. Purified iron becomes thick and assumes the form of white spongy iron balls, known as puddle balls, the weight of which is about 50 to 70 kg
Conversion of pig iron into wrought iron by stirring in a molten state is known as puddling. It is carried out in a reverberatory furnace. In this type of furnace, the metal does not come into contact with the fuel, and flame from the fire is reverted or sent back on the metal in the hearth. The combustion chamber and the chimney are situated at opposite ends. Next to the combustion chamber is the hearth portion with shallow depth. Hearth lining consists of molten slag or rich iron ore. It is supported on steel plates, which in turn are supported on dwarf brick walls. Water jackets are provided for circulation of water to cool the furnace. Various doors or openings for fuel feeding, The roof is given a peculiar shape so that flames of gas produced are concentrated on hearth.
By this operation, the slag contained is removed. It may be achieved by forging the balls under a power hammer or by passing the balls through a squeezing machine. In the case of the power hammer, the balls are placed on an anvil and a falling hammer forges them. A squeezing machine consists of two cylinders, which are placed one inside the other. The smaller cylinder has corrugations on its outer surface and the larger cylinder has corrugations on its inner surface. The balls are placed in between the cylinders and then the inner cylinder is rotated. Shingling also helps in binding or welding the particles of puddle balls. The material obtained at the end of shingling is known as bloom and it is still in red-hot condition.
Bloom is passed through grooved rollers and flat bars of sizes such as about 4 m � 10 cm � 25 mm are obtained. These bars of wrought iron of poor quality are called muck bars. To improve the quality of wrought iron, these bars are tied together by wires, a process known as faggoting and they are heated and rolled again. Process may be repeated several times to get wrought iron of desired quality.