Metals are divided into two general roups: ferrous metals and non-ferrous metals.

      Nonferrous metal, also knowns as a narrow non-ferrous metals, all metals are collectively refered to as iron, manganese,chromium outside. Generalized non-ferrous metals also include non-ferrous alloys. A ferrous alloy is an alloy of non-ferrous metal substrate(typically greater than 50%),by adding one or several other clements constituted.

      Usually refers to the removal of non-ferrous iron(sometimes also remove manganese and chromium) for all metals and iron-based alloys outside. Heavy metals can be divided into non-ferrous metal (such as copper,lead,zinc),light metals(such as aluminum,magnesium),a noble metal(such as gold,silver,platinum), rare metals (such as tungsten,molybdenum,germanium,lithium,lanthanum,uranium).

     Ferrous are those metals whose major element is iron. The major types of ferrous metals are irons, carbon steels, alloy steels and tool steels.    

           Iron

     The iron we find in the earth contains some impurities which we must remove by smelting. The remaining metal after special smelting is pig-iron, which consists of approx. 93% iron,5% carbon,and 2% impurities.

      Remelting pig-iron and scrap iron in a furnace to remove some of the impurities produces cast iron.The three primary types of cast iron are gray cast iron,white cast iron and malleable iron.

     Gray cast iron is primarily used for cast frames,automobile engine blocks, hand wheel,and housings. White cast iron is hard and wear resistant and is used for parts such as train wheels. Malleable cast iron is a tough material used for tools such as pipesand wrenches. Generally,cast irons have very good compressive strength, corrosion resistance,and good machining property.   

         Carbon Steel

      Carbon steel is made from pig-iron that has been refined and cleaned of most impurities.The 3 principal types of carbon steel used in industry are low,medium,and high carbon steel.The percentage of carbon is the most important factor in determining the mechanical properties of each type of carbon steel.

       Low carbon steel contains between 0.05% and 0.3% carbon and is used for parts that do not require great strength. Typical uses of low carbon steel include chains,bolts,screws,washers,nuts,pins,wire,shaft and pipes. This metal is also known as machine steel,mild steel, and cold-rolled steel.Low carbon steel is of good ductility that is easily machined and welded. It is useful for parts that must be stamped or formed.

      Containing between 0.3% and 0.5% carbon, medium carbon steel is used for parts that requires better strength,such as gears,crankshafts,machine parts and axles. It can be heated-treated to increase both hardness and wear resistance because of it’s higher carbon content. Medium carbon steel is a kind of metal with better toughness and strength,easier to be welded.

   High carbon steel,containing between 0.5% and 1.7% carbon,is used for parts such as files,knives,drills,razors and woodworking tools.Due to their increased carbon content, high carbon steels can be heat-treated to make them harder and more wear-resistance than low and medium carbon steel.

         Alloy steels

       Alloy steels are basically carbon steels with elements added to modify of change the mechanical properties of the steel. All steels are alloy steels because each is a combination of elements,including carbon steel,a mixture of iron and carbon. To identify the two groups,one is called carbon or plain steel and the other is referred to alloy steel. Alloying elements are added to the molten steel in measured amounts. The desired end product determines the elements and amounts added.