Metalwork - Materials - Types of Steel
There are many different types of Steel, and covered here are the main types that you may be working with. They are divided into 2 categories.
The two main types of Mild Steel that you will come in contact with are Black Mild Steel and Bright Mild Steel. Below you can see pictures of both. Black Mild Steel has a dark blue oily surface, and Bright Mild Steel has a silvery grey surface. Because Bright Mild Steel is cold rolled it is accurate in size whereas Black Mild Steel is not as accurate. Mild Steel is reasonably soft and ductile. It is easily cut and machined and is a good material to practice welding on. The reasons for this is its carbon content, which varies between 0.15% and 0.3%. Some of the uses of Mild Steel are :Ship Hulls, Garden Gates, Girders, General Structural Steel, etc.
You are unlikely to work with Dead Mild Steel in the Metalwork room, however it is usefull to know some information about it. Dead Mild Steel has a carbon content of between 0.05% and 0.15%. This gives Dead Mild Steel the property of good Ductility and the ability to be easily formed. Some of the uses of Dead Mild Steel are : Tinplate, Car Bodies, Chains, Nails, Thin Wire, etc.
Medium Carbon Steel is much stronger then Mild Steel. Its Hardness and Strength can be increased by Heat Treatment, but the ammount of improvement depends on the carbon content of the steel. Medium Carbon Steels contain between 0.35% and 0.5% carbon. Medium Carbon Steel is generally used where the stresses are greater then could be withstood by Mild Steel. Some of the uses of Medium Carbon Steel are : Rail Tracks, Vehicle Axels, Garden Tools, etc.
High Carbon Steel has a carbon content of between 0.55% and 1.5%. This gives it the properties of hardness and good wear resistance. It can be hardened and tempered after which it is used for most workshop cutting tools. Some of the uses of High Carbon Steel are : Chisels, Files, Drills, Springs, Taps etc.
Tinplate is actually Mild Steel coated with Tin. The Tin provides the Mild Steel with a protective layer that prevents corrosion, and also makes the metal more aesthetically pleasing. When working with Tinplate it is importand not to scratch the metal as this will remove the Tin fromn the Mild Steel, and allow the metal to rust. When marking out Tinplate you should use a pencil instead of a Scriber. After cutting it is important to tin the edges. Because Tinplate is corrosion-resistant, non-toxic, and easy to solder it is used widely in the food industry as containers. YOu can get Tinplate from biscuit tins, food tins, etc. Some of the uses of Tinplate are : Food Containers, Paint Tins, etc.
High Speed Steels is classed as an Alloy Steel. Alloy Steels containd other Elements other than Carbon, in order to improve the physical properties of the steel. High Speed Steel usually contains about 17% Tungsten, 5% Chromium, 1% Vanadium as well as 0.8% Carbon. The quantities of the alloying elements varies depending on the properties that the engineer wants for the High Speed Steel. In some cases other elements, such as Cobalt are also added. High Speed Steel is also referred to as HSS. The alloying elements in HSS give it great hardness after it has been heat-treated. This results in the fact that High Speed Steels retain their hardness even when they are extremely hot, and so it is a very good metal to be used for cutting tools. Some of the uses of High Speed Steel are : Drills, Lathe Cutters, Hacksaw Blades, etc
Stainless Steels is also classed as an Alloy Steel. The main alloying elements are Nickel and Chromium. It has a very high resistance to corrosion and as a result is ideal for areas where clenliness is important. There is a wide range of Stainless Steel available especially in the in the area of medicine and food preperation. Some of the uses of Stainless Steel are : Surgical Instruments, Cuttlery, Kitchen Sink, etc