Metallic Materials MLZ 109 PDF

METALLIC MATERIALS  Related Courses MLZ 216 Mechanical Behaviour of Materials (4th semester) MLZ 327 Mechanical Behaviour of Materials II (5th semester) MLZ 315 Electrochemistry (5th semester) MLZ 335 Metallic Materials I (5th semester) MLZ 336 Metallic Materials II (6...

METALLIC MATERIALS  Related Courses MLZ 216 Mechanical Behaviour of Materials (4th semester) MLZ 327 Mechanical Behaviour of Materials II (5th semester) MLZ 315 Electrochemistry (5th semester) MLZ 335 Metallic Materials I (5th semester) MLZ 336 Metallic Materials II (6th semester) MLZ 447 Materials Processing Laboratory II (7th semester) MLZ 455 Heat Treatment (7th semester) MLZ 457 Manufacturing with Materials (7th semester) MLZ 459 Degradation of Engineering Materials (7th semester)  Definition of a Metal 1. The electropositive elements & alloys based on these elements. The electron bond structure of a metal is characterized by a partially filled valence band. 2. An element that readily forms positive ions (cations) & has metallic bonds. Periodic Table of The Elements ❑ Approximately 50 metallic elements; however, only a few produced and used in large quantities in engineering practice. ❑ Most important metallic element is iron (Fe) to make steels & cast irons. ❑ For structural use, order of importance of metals is: Fe → Al → Cu → Ni → Ti Abundancy of Elements  Typical Properties of a Metal ❑ Shiny ❑ Ductile & malleable (işlenebilir) ❑ Relatively high melting temperature ❑ Relatively hard ❑ Good conductors of heat & electricity ❑ Sound (sağlam)  Metals & Alloys ❑ The degree to which different metals are used is determined largely by economic considerations. ❑ Contributory factors are the availability of suitable ores & the amount of difficulty encountered in recovering the metal from them. ❑ Progress in extractive methods produced dramatic changes in the overall picture.  Ferrous Alloys ❑ Most produced metal type. ❑ Most widely used engineering construction material: a) Abundant Fe-containing compounds b) Produced by using relatively economical extraction, refining, alloying & fabrication techniques. c) Versatile → mechanical & physical properties can be tailored according to the needs.  Fe as a Base Material Advantages: ❑ Relatively high melting temperature (1538 C) ❑ Retains strength to high temepratures (TH = 450 C) ❑ Highest elastic modulus (E) of the common metals (205 GPa) ❑ Common: thousands of years supply ❑ Cheap & easy to make: Fe2O3 + 3  CO  2  Fe + 3  CO2 ❑ Easy to recycle ❑ Ductile ❑ Can be cast ❑ Easy to weld ❑ Heat treatable to a wide range of strengths and toughness values ❑ Easy to alloy: can dissolve large amounts of Cr, Ni, Co, Cu, …  Refinement of Steel from Ore Coke Iron Ore Limestone BLAST FURNACE heat generation gas C+O2 →CO2 refractory vessel reduction of iron ore to metal layers of coke CO2 + C → 2CO and iron ore 3CO + Fe2O3 →2Fe+3CO2 air purification slag Molten iron CaCO3 → CaO+CO2 CaO + SiO2 + Al2O3 → slag Disadvantages/Limitations: ❑ BCC phase has a low ductile-to-brittle transition temperature (DBTT)  brittle at low temperatures ❑ High density (7.87 g/cm3) ❑ Relatively low conductivity ❑ Poor corrosion resistance  Classification of Metals Metal Alloys Ferrous Non-ferrous Steels Cast Irons Copper alloys High Alloy Aluminium alloys Gray Iron Low Alloy Titanium alloys Ductile Iron Low Carbon Magnesium alloys White Iron Medium Carbon Superalloys Malleable Iron High Carbon  Taxonomy of Metals Metal Alloys Adapted from Ferrous Nonferrous Fig. 11.1, Callister 7e. Steels Steels Cast Irons Cast Irons Cu Al Mg Ti 100 11