Machining Capability of Grey Iron Castings The matrix however is quite responsive to heat treatment just as in the case of steel. Although the graphite may increase in volume if a pearlitic iron is completely ferritized, in which case, the graphite is usually deposited on the flakes originally present. Such heat treatment will not change the graphite structure. But For some purposes, gray iron castings can also be heat treated, such as to relieve residual stresses, improve machinability, increase the hardness of the surface either through induction or flame hardening, or harden the entire section through an oil quench and draw treatment. Most of the time, grey iron castings are supplied to our customers in the as-cast condition directly. As good rigidity of resin sand and high strength of sand mould when early casting,then we could effectively eliminate the shrinkage cavity, shrinkage defects of gray iron castings. Compare with other sand casting processes, resin sand casting is relatively precise casting method close to investment casting. Resin Sand Casting: Main sand casting process for small and medium castings. With lost foam casting process, we can help our customers to obtain high accuracy products with excellent surface finish, and less machining operations will be done. Lost Foam Casting: The only investment casting process for cast iron components, which has lots of advantages to produce small gray iron invesmtent castings, such as saved mould cost, shorten production cycle and improve production efficiency. In our foundry, we can make grey iron castings in below two types: The processes using sand as the mold media have a somewhat similar effect on the rate of solidification of the casting, while the permanent mold process has a very marked effect on structure and properties. Frequently Used Grey Iron Grades Gray IronĬommonly used process for grey iron castings in the market is produced by sand casting. Compared to other iron castings, gray iron has a low tensile strength and ductility that is why the impact and shock resistance of this kind of material is almost non-existent. Gray iron is generally considered easy to weld. Whe casting, the silicon element can promote good corrosion resistance and increase fluidity when casting. Grey iron also has less solidification shrinkage than other cast irons because of the graphite microstructure. Besides, because the graphite flakes self lubricate, it also has good galling and wear resistance. For the graphite lubricating the cut and breaking up the chips, grey iron is a common cast alloy due to its relatively low cost and good machinability. We call this kind of material grey iron because of the gray color of the fracture. Grey iron, or grey cast iron, is a material type of cast iron with graphitic microstructure.
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