DONG GIA MECHANICAL CO., LTD

1. What is Gray Iron?

Gray iron  is a type of cast iron containing 3.3-3.8% carbon in the form of free graphite. They have a graphite microstructure mainly in the form of plates. Sometimes in the form of plates or chains. The surface of gray cast iron is dark gray. That is the characteristic color of ferrite and free graphite. Because graphite has poor mechanical strength, gray cast iron is brittle. It has low tensile strength, ductility and toughness. However, graphite has the advantage of increasing wear resistance and reducing shrinkage when casting gray cast iron. This makes cast iron suitable for materials that require lubrication containing oil. Suitable for manufacturing bearings, gears, machine bodies, machine bases, water pipes, etc.

This is the most common and oldest type of cast iron. It is widely used in the field of mechanical engineering. Its crystals contain various small fractures. These fractures are responsible for the grey appearance.

2. Advantages & benefits of grey cast iron:

Advantage:

• Low cost
• Easy to smelt (melting point 1350 degrees C)
• No strict requirements on impurities
• Cast iron has good casting properties and high sound deadening ability.

Disadvantages:

• Cast iron is brittle, has poor bending resistance and cannot be forged.
• When cooled rapidly, cast iron turns white, making it difficult to machine.

3. Applications of gray cast iron in industry

Due to the application characteristics of gray cast iron, it is widely used in the machine manufacturing industry, casting large, highly complex machine belts, parts that do not need to withstand large bending forces, but need to withstand good compressive forces. There are devices, gray cast iron materials can be used up to 70% of the total weight. Machine tool belts (lathes, milling machines, planers, etc.), internal combustion engine bodies, etc. are also products made from gray cast iron.