Gray iron

Gray iron Unlike ductile iron, gray iron is a type of cast iron in which carbon crystallizes into narrow, elongated flakes. To produce cast iron, more carbon must be added to the molten iron than needed to produce steel. Most grades of steel contain less than 1.2% carbon, while cast iron typically contain 2.5% to 4% of carbon. Adding carbon lowers the iron’s melting point and makes the metal more fluid, allowing us to manufacture parts with more complex shapes.

Gray iron is mainly used because of its ease of machining and its lower cost of production. When exposed to significant impact, these flakes can cause cracks to propagate in the metal. However, despite showing limited impact resistance, gray iron possesses remarkable properties, including the following:


Advantages of Gray iron

  • High compressive strength
  • Easy to mold
  • Abrasion resistance
  • Good machinability
  • Good wear resistance
Gray iron properties
ASTM A-48 Grade Tensile strenght (PSI) Typical Brinell hardness
CL 25  25 000  196-228
CL 30 30 000 212-241
CL 35 35 000 217-248
CL 40 40 000 217-269


Equivalent grades of gray iron
ASTM A-48 Grade DIN 1691 EN 1561  ISO 185
CL 25 GG-15 EN-GJL-150  150
CL 30 GG-20 EN-GJL-200 200
CL 35 GG-25 EN-GJL-250 250
CL 40 GG-30 EN-GJL-300 300