STEEL - STEEL Steel is made up of iron, coal, and...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
STEEL Steel is made up of iron, coal, and limestone. Alloy of iron and carbon to about 2% or less. Owes it diverse properties to allotropy, or changeable crystalline structure of iron. As iron cools below the melting temp. of 1538 c. (2800 f.) its atoms align themselves into a body-centered cubic structure. They form cubes with an atom at each corner and one in the center. Iron Ferrite. When iron cools below 2541f. it becomes austenite, which is face centered, atom at each corner and one in center of face. Carbon remains dissolved more readily in austenite than in ferrite because there is more room bt. Atoms. In principle steel making is a melting, purifying (refining), and alloying process carried out at 1600 C. (2900 f.) under molten conditions. Comes from pig iron or scrap metal, refined in basic oxygen or open hearth, electric arc used for scrap metal. When refined alloys are added. INGOTS – Molten steel can be poured into molds for solidification, these can later be reheated and rolled into semi finished shapes such as blooms or slabs. CONTINUOUS CASTING – molten steel is tapped from a ladle into a mold, extracted as a long strand, and immediately cut, worked, and treated in one continuous operation. 3 categories Carbon steels – most widely used 90% of worlds production Low alloy – exceptionally strong and used for machine parts, bridges etc. High alloy – more than 8% alloy elements Iron ore mined in open pits, shipped from the Lake Superior region Coal Mining – coke what is left over after gases, hydrocarbons have been removed, very hard and does not crush under iron, burns evenly, coke ovens coke coal – no oxygen, remove brick dose with water to take blast furnace Limestone quarries – serve as a flux, impurity magnet liberated in the blast furnace, melts in furnace, combines with unwanted materials and then floats to the top – Slag Blast Furnace – White hot liquid iron, vertical steel cylander lined with heat resistant refractory brick in which materials are melted down by blast of hot gas. Bessemer Furnace - lined with ganister, a silica, air was blown from the bottom through a charge of molton pig iron, Bessemer realized that the subsequent oxidation of the silicon and carbon in the iron would release heat and that, if a large enough vessel were used, the heat generated would offset the heat lost. 15 minutes of 1650cf. heat could charge a ½ ton. Steel Furnace – reduce amount of carbon in iron, Bessemer, open hearth to the Blast Oven Furnace, 300 tons in 45 min. vs 5 in 8 hours in open hearth. Oxygen combines with all the undesirable elements to make steel pear-shaped vessel lined with refractory material. Blow oxygen over molten metal, add flux, 3000 d.f. pour out steel Alloys then added, tungsten-heat resistant, chromium/nickel-stainless steel, molybdenum – hardenability Hot-working – consists primarily of hammering, pressing, rolling, and extruding under high heat.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Cold-working – includes rolling, extrusion and drawing (pulling through a die.) bright surface bars, wire,
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/24/2008 for the course ARCH 3007 taught by Professor Ursula during the Spring '08 term at LSU.

Page1 / 9

STEEL - STEEL Steel is made up of iron, coal, and...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online