Carbon steel is the most common type of steel. It is a combination of two elements, iron and carbon. Carbon steels which can successfully undergo heat-treatment have a carbon content in the range of 0.30% to 1.70% by weight. High carbon steel has a much better tensile strength and can be used for various projects. 

Alloy steel is steel that is alloyed with a range of elements in total amounts between 1.0% and 50% by weight to improve its mechanical properties. Alloy steels are broken down into two groups: low alloy steels and high alloy steels. There is a variety of improved properties in alloy steels such as: hardness, toughness, wear resistance, corrosion resistance, hardenability, and hot hardness.

Tool steels are high-quality, carbon and alloy steels. They are usually melted in furnaces and processed to give them properties required for shaping other metals into useful components. There are six groups of tool steels: water-hardening, cold-work, shock-resistant, high-speed, hot-work, and special purpose.

Stainless steel is a steel alloy, composed of chromium, iron, and carbon. Resistance to corrosion and staining, low maintenance, and familiar luster make stainless steel an ideal material for many applications where both the strength of steel and corrosion resistance are required.

Aluminum is the most widely used non-ferrous metal. Aluminum is almost always alloyed, which significantly improves its mechanical properties, especially when tempered. It is used in a wide variety of commercial applications. Aluminum is highly conductive, has adequate mechanical strength and low density, and resists corrosion. 

Red metal is a term used for the popular alloys we know as copper, bronze, and brass. Although all three metals are similar in color, they are different when it comes to composition, qualities, and more. 
Copper is resistant to corrosion, highly durable, malleable, and retains superior thermal and electrical conductivity. Bronze is an alloy of copper, containing copper, as well as, other materials like tin or aluminum. Brass is simply an alloy made from copper and zinc.