Chapter 1 - Metals Flashcards
Ferrous metals
Metals that contain iron (ferrite) and carbon
Non-ferrous metals
Metals that do not contain iron (ferrite)
Ferrous alloys
A mixture of two or more metals - at least one of which contains iron (ferrite) and carbon
Non-ferrous alloys
Mixtures of two or more metals - none of which contain iron (ferrite).
Iron
Iron (ferrite) is converted from its ore by heating. The resulting impurities (slag) are removed from the furnace leaving a soft greyish metal once cooled. Iron is rarely used without combing with carbon, this gives it greater strength. The result of this combination is steel. This can be alloyed with other metals in order to enhance particular properties.
Crystal
The main building block of most, if not all metals.
Steel
A mixture of iron and carbon. The amount of carbon present in the material determines the material’s initial strength. Alloying with other metals enables specific properties such as strength, toughness and resistance to corrosion to be enhanced.
Carbon
Carbon is an element found in a range of materials. Carbon is found in most organic materials; materials such as coal and diamond are made up purely of carbon. The amount of carbon in a steel has the effect of increasing strength and hardness.
Copper
A brownish-looking metal; it can be alloyed with zinc to produce brass, or with tin to produce bronze.
Bauxite
the most common metal in the Earth’s crust - can be made into aluminium using processes such as electrolysis
Oxidation
When a material comes into contact with oxygen, the result is an oxide layer that forms over the surface of the metal. In most metals this serves to protect the material from further oxidation, but in the case of steels, this oxide layer is porous and so allows further oxidation.
Work hardening
Name given to the effects of processing ie. rolling, bending or hammering a material when it is cold. (without the use of heat). While being cold worked, the metal’s crystal structure is distorted. This in turn created internal stresses that are responsible for making the material harder (and therefore increasing strength)
Planishing
Giving a final finish to metal by hammering or rolling it to produce a smooth surface.
Normalising
A heat treatment that is applied to steels to obtain crystals of smaller, more regular size, thereby making the material tougher and stronger.
Annealing
A process of heating a metal that has been work hardened. ‘Soaking’ the metal at an appropriate annealing temperature allows the crystals to reshape, so relieveing internal stresses that cause work hardening.
