Gray iron is a kind of cast iron. Carbon is present in the form of flake graphite in cast iron. The fracture surface is gray. Have good casting, cutting performance, good wear resistance. For the manufacture of racks, boxes and so on. Gray cast iron graphite is flaky, effective bearing area is small, graphite tip easy to produce stress concentration, so the strength, plasticity, toughness of gray iron is lower than other cast iron. But it has excellent damping resistance, low notch sensitivity and high abrasion resistance.