General properties of iron

1. GENERAL PROPERTIES OF IRON \\ Physical \\ Mechanical \\ Chemical

2. ____Iron____

3. ____Physical Properties____ Iron is a silvery-white or grayish metal. It is ductile and malleable. Ductile means capable of being drawn into thin wires. Malleable means capable of being hammered into thin sheets. It is one of only three naturally occurring magnetic elements. The other two are nickel and cobalt Iron has a very high tensile strength. Tensile means it can be stretched without breaking. Iron is also very workable. Workability is the ability to bend, roll, hammer, cut, shape, form, and otherwise work with a metal to get it into a desired shape or thickness. The melting point of pure iron is 1,538°C (2,800°F) and its boiling point is about 2,862°C (5,182°F). Its density is 7.874 grams per cubic centimeter. The melting point, boiling point, and other physical properties of steel alloys may be quite different from those of pure iron.

4. ____Mechanical Properties____ The mechanical properties of iron and its alloys can be evaluated using a variety of tests, including the  Brinell test ,  Rockwell test  and the  Vickers hardness test . The   Brinell scale  characterizes the indentation  hardness  of materials through the scale of penetration of an indenter, loaded on a material test-piece. It is one of several definitions of hardness in materials science . I t was the first widely used and standardized hardness test in  engineering  and metallurgy.

5. The typical test uses a 10 millimeters (0.39  in)  diameter   steel  ball as an indenter with a 3,000  kgf  (29  kN ; 6,600   lbf ) force. For softer materials, a smaller force is used; for harder materials , a  tungsten carbide  ball is substituted for the steel ball. The indentation is measured and hardness calculated as : where : P  = applied force ( kgf ) D  = diameter of indenter (mm) d  = diameter of indentation (mm) ____Brinell Test____

6. The Rockwell scale is a  hardness scale based on the  indentation hardness of a material. Indentation hardness tests are used to determine the   hardness  of a material to deformation . The examined material is indented until an impression is formed . When testing metals, indentation hardness correlates linearly with   tensile strength . ____Rockwell test_____

7. The Vickers hardness test  was developed as an alternative to the Brinell  method to measure the   hardness  of materials . The Vickers test is often easier to use than other hardness tests since the required calculations are independent of the size of the indenter, and the indenter can be used for all materials irrespective of hardness. The basic principle , as with all common measures of hardness, is to observe the questioned material's ability to resist plastic deformation from a standard source . The Vickers test can be used for all  metals  and has one of the widest scales among hardness tests. ____Vickers Hardness Test____

8. The unit of hardness given by the test is known as the Vickers Pyramid Number  (HV) or Diamond Pyramid Hardness  (DPH). The hardness number can be converted into units of  pascals , but should not be confused with a pressure , which also has units of pascals . The hardness number is determined by the load over the surface area of the indentation and not the area normal to the force , and is therefore not a pressure.

9.  The unit of hardness given by the test is known as the Vickers Pyramid Number (HV) or Diamond Pyramid Hardness (DPH). The hardness number can be converted into units of  Pascal's , but should not be confused with a pressure, which also has units of Pascal's. The hardness number is determined by the load over the surface area of the indentation and not the area normal to the force, and is therefore not a pressure. The HV number is then determined by the ratio  F/A  where  F  is the force applied to the diamond in kilograms-force and  A  is the surface area of the resulting indentation in square millimeters.  A  can be determined by the formula where  d  is the average length of the diagonal left by the indenter in millimeters. Hence , where  F  is in  kgf  and  d  is in millimeters. where   F  is  newtons  and  d  is millimeters.

10. Chemical Properties Iron is a very active metal. It readily combines with oxygen  in moist air. The product of this reaction, iron oxide (Fe  2  O  3  ), is known as rust. Iron also reacts with very hot water and steam to produce hydrogen gas. It also dissolves in most acids and reacts with many other elements .