UNIT 4: Ferrous and Non-Ferrous alloys Manufacturing Engineering Unit 4 Copyright © 2012 MDIS. All rights reserved. 1

By the end of this unit, you should be able to: Name the processes for manufacture State the applications of various alloys State the characteristics of some alloys -2Unit 4 Copyright © 2012 MDIS. All rights reserved.

Production of Iron and Steel Raw materials : Iron ore, Limestone and Coke They are carried to the top of a blast furnace and dumped into it blast furnace-a large refractory lined container where extremely high temperatures relevant to the production of steel can be established and maintained numerous reactions that take place, but the basic oxidation reactions are what converts the iron ore to pure iron- This is called reduction reaction of the ore Molten metal accumulates at the bottom of the furnace -3Unit 4 Copyright © 2012 MDIS. All rights reserved.

Steel making basically the refining pig iron by the reduction of the manganese, silicon, carbon and other elements in a controlled composition with the addition of various alloying elements Open hearth- the shallow hearth shape is open directly to flames that melt the metal. It has been replaced by the electric and the basic-oxygen furnaces in most industries for their higher efficiency and quality. Electric Furnace- Using a continuous electric arc as the source of heat, temperatures up to 1925C can be maintained accurately in this furnace 4Unit 4 Copyright © 2012 MDIS. All rights reserved.

Metal and carbon and limestone are dropped into the furnace the electrodes are lowered. Once the arc is established, within 20 hours the metal melts as the current is shut off and electrodes are withdrawn. The molten metal is than emptied into a ladle for pouring into the subsequent process. Basic Oxygen furnace the fastest process for steel making Pure oxygen is blown into the furnace for 20 minutes at 1250 kPa. Flux agents are added and agitation of the oxygen refines the molten metal. The metal is tapped by tilting it an slag is removed by tilting in the opposite way 5Unit 4 Copyright © 2012 MDIS. All rights reserved.

Casting of Ingots Ssteel produced has to be transformed into Ingots. These are the basic form for post processes like rolling, forging, hot and cold working etc. Ingots are formed by pouring the molten steel into solid form. The ingots are in the form of casting pits- made of cupola iron or blast iron. Cooled ingots are lowered into soaking pits, where they reheat to 1200C for rolling. Shapes include square, rectangular or round weighing up to 36 tonnes. 6Unit 4 Copyright © 2012 MDIS. All rights reserved.

Continuous Casting down stream processes are fed directly from the molten to feed stock in a continuous way arrangement includes a ladle with temperature equalization metal is poured into a refractory lined intermediate vessel to skim off impurities molten metal travels down water cooled copper molds, and begins to solidify. However the path has pinch rolls that support the solidifying metal. The speed of travel is set at 25mm/s with shell thickness of 18mm. Water sprays cool the metal as it progresses and surface of the molds have graphite to lubricate the motion. -7Unit 4 Copyright © 2012 MDIS. All rights reserved.

Aluminum and its alloys Aluminium alloys are available as ingots and wrought products to be converted further by rolling, extrusion Wrought Aluminium: These include alloys that can be cold worked and those that can be hardened by heat treatment. Cast aluminium 8Unit 4 Copyright © 2012 MDIS. All rights reserved.

Copper and its alloys alloys are similar to Aluminium and its alloys Zn- the alloys are called Brass, used extensively in water related applications like valves, decorative sheets and stock, Sn (tin)- Bronze made with tin and with aluminium are both prevelant. Beryllium Copper- also used with brass and bronze they have good strength, and hardness and are used in springs and bearings. Copper Nickel and Nicklel Silvers. Unit 4 Copyright © 2012 MDIS. All rights reserved. 4-9