Metalwork - Materials - Metals
The study of Metals has been one of man's greatest pastimes for a long, long time. And your thinking that there are a lot of better pastimes, sleeping being one! But ever since the Bronze Age there has been a huge connection between the ascent of man and Metals. Although the course that you are doing is properly called 'Materials Technology' there is still more of an emphasis on Metals than the other type of material, and so it is very important that you get develop a good knowledge of the basics.
Metals as a topic is a huge one, so below we have broken it down into sections that give brief explantaions, of what the section is about. From there you can then go on to get more detailed information.
There are a lot of metals used in Engineering, however those based on iron are by far and away the most important and widely used. As a result metals are broken into 2 categories. Those that are based on Iron and those that are not. Ferrous is the Greek word for Iron and is the name given to all metals which are based on this metal. Steel is a Ferrous metal because its main constituent is Iron. A quick and easy way to tell if a metal is Ferrous or not is to use a magnet. Iron is magnetic and as a result so are all Ferrous metals, so a magnet will stick to a Ferrous metal. You can compare different Ferrous against eachother in the workshop and you can find out how to do this by going to the Comparison Page.
Knowing what Ferrous metals are you should be able to guess what Non Ferrous metals are. Yep... they are metals that are not based on Iron. Examples of Non Ferrous metals are, Aluminium, Brass, Copper, Lead, Tin, etc. Again you can use a magnet to tell that a metal is Non Ferrous. Naturally the magnet will not stick to a Non ferrous metal.
Iron is very rarely found in its natural form. It has to mined in the form of Iron Ore. The Iron Ore contains large amounts of materials that are not wanted such as rocks, clay, and sand and they have to be removed. The Iron itself is chemically combined with Oxygen and is called Iron Oxide In order to remove all of the impurities the Iron Ore has to be Smelted, and this is done using a Blast Furnace.
You see a lot more Steel around you than you do Iron. Think
of cars, cutlery, even the kitchen sink. Steel is made from
Iron mixed with Carbon. The two methods of producing Steel
from Iron are The Basic Oxygen Process and the Electric Arc Process.
An alloy is defined as a mixture of two or more metals. Engineers make alloys in order to improve the properties of pure metals, that is those that you can find in the Periodic Table Of The Elements. Take Copper for example. A long long time ago man found, (probably by accident), that if he mixed Copper and Tin, the result was another metal that was tougher and harder, but kept the basic properties of both Copper and Tin. This new metal was called Bronze. Now man had a "new" metal that allowed him to create a lot more items. This new age in history was called the Bronze Age. Later it was found that mixing Copper and Zinc resulted in a shiney, gold like metal which we now call Brass. The Alloying of metals is an industry in itself nowadays. There are so many different types of Steels, Aluminiums and other non-pure metals that engineers are kept busy enough creating and improving. Be careful, Plain Steel is not an Alloy, by definition, as it is only a mixture of Iron and Carbon. Carbon is not a metal. Having said that most Engineers call plain Steel an alloy. However, other types of Steels are Alloys as there are small amounts of other metals mixed in.
Aluminium making up 8% of the earth's crust is the third most common Element. It is used widely in the engineering industry because of it properties which make it extremely useful, and with alloying there are many different types of Aluminium for different uses. Some of these are : Tin cans, Aluminium Foil, Structural Elements, Guttering, Window Frames, Aircraft Bodies, Vehicle Bodies, Electrical Wire, etc. The full list is to extensive to be covered here. If you wish to get a lot more information on Aluminium then goto the Aluminium page.
Copper has a reddish brown colour, and after weathering turns a green colour. It is Ductile and Malleable. It is also an excellent conductor of heat and electricity, and is easy to Solder and Braze. Copper is the base metal in the alloy metals of Brass and Bronze. Copper hardens with age and with working. This is called Work Hardening. This can be reversed by Annealing, which is where you heat up the Copper to red hot and then quesch it in water. Copper has many uses, but because it is becoming expensive to produce, and is found less abundantly in the Earth's crust, other metals are being used for the same purposes more and more. Some of Copper's uses are : Electrical wiring, water plumbing and piping, roofing, soldering iron bits, in the manufacture of brass and bronze, etc.
Lead as you should know is highly toxic, and has been removed from petrol, giving Unleaded Petrol. As a result you will not be using this material in the Metalwork room. However it is good to know something about it. Lead has the highest density of the common metals making it relatively heavier. After weathering it has a dull grey colour, but it is slightly shiny and greyish-blue, when cut. It is soft and Malleable. It is actually so soft that you could bend 5mm sheet Lead in your hands without any difficulty, but don't try this, take our word for it. Eventhough Lead is toxic it still has many uses : car batteries, protection against X-rays, chimney flashing, etc.
Brass is an alloy of Copper and Zinc. The percentage of Zinc in the alloy varies to give the Brass different porperties. Brass has a yellow "gold" like appearance and is considered to be a very pretty metal. Eventhough it is a relatively hard material is is reasonably easy to machine. When filing, hacksawing or turning on the Lathe, the Brass breaks off into small chips. Brass has a good resistance to corrosion. Brass has many uses and many are as a result of its appearance : plumbing fittings, screws, brazing spelter, electrical fittings, ornamental work, etc.