Shenynang Gongda Heavy Equipment Manufacturing is a pro […]
Shenynang Gongda Heavy Equipment Manufacturing is a professional manufacturer and supplier of Ni-hard iron castings. Now let's talk about the production of this casting. Interested friends will go ahead and look at it.
1. Casting process: Nickel hard cast iron can be cast by sand mold or metal mold with linear shrinkage rate of 1.6% ~ 2.0%, usually 1.8%. The casting process is the same as that of ordinary white cast iron. Risers are usually used and sprues enter the casting through risers to form good sequential solidification conditions.
2. Melting: Nickel hard cast iron is preferably done by electric furnace (induction furnace or electric arc furnace) in order to control chemical composition and tapping temperature. Ni-Hard l and Ni-Hard 2 are smelted in cupola in some countries, but Ni-Hard 4 is not easy to be smelted in cupola so as not to cause burning loss of alloy elements, especially chromium elements. Chromium is easy to combine with carbon to form carbides, which makes the carbon content unable to be accurately controlled. The determination of nickel and chromium content should consider the casting wall thickness. In order not to precipitate graphite in the structure, there should be a proper fit between C, Si, Cr and the wall thickness of the casting.
3. The melting point of cast nickel hard cast iron is higher than that of gray cast iron, and its fluidity is lower than that of gray cast iron. Therefore, its casting temperature should be higher than that of gray cast iron. Usually, the pouring temperature of nickel hard cast iron is 1400℃, for thick and large castings, the pouring temperature can be appropriately reduced, but should not be lower than 1350℃.
Click here to learn more about castings: wear resistant castings.