Main sources of iron:
* second most abundant metal (5% by mass) in Earth’s crust (fourth most abundant element) * found in rock (a mixture of minerals) as one or more minerals (usually a compound) * if a mineral is of economic importance, it is referred to as an ore * iron containing minerals include hematite (Fe2O3), magnetite (FeO·Fe2O3 or Fe3O4), limonite (FeO(OH)·nH2O) and siderite (FeCO3) Alloys:
* homogeneous mixtures of metals or metals and non-metals * examples include brass (65% copper, 35% zinc), solder (63% tin, 37% lead), bronze (85% copper, 15% tin) * usually alloys resist corrosion, and can be harder than either of the metals * the added species interferes with the metallic lattice of cations in the pure metal, and as a result the physical properties of the metal are altered * steels are alloys of iron, with different quantities of carbon and other metals (titanium, chromium, molybdenum, cobalt, nickel, manganese, tungsten) added to create desired properties: * chromium makes steel harder and more resistant to corrosion * manganese makes steel stronger, harder and more resistant to wear * silicon makes steel more resilient
* molybdenum makes steel stronger and harder at high temperatures, less brittle, corrosion resistant and easier to weld * tungsten makes steel extremely hard, even at high temperatures
* TYPES OF STEEL
* Carbon Steel. This is the most widely used kind of steel. Its carbon content is under 2 percent and is usually less than 1 percent. It often also contains a little manganese. * Stainless Steel. This is the most corrosion-resistant kind of steel. It normally contains at least 12 percent (and sometimes up to 30 percent) chromium, and it usually also contains nickel. A very popular stainless steel formulation is 18-8, 18 percent chromium and 8 percent nickel. * Alloy Steels. These contain a little carbon, and sometimes silicon, but they mainly...