After solution treatment, there will still be a small amount of undissolved carbides in high manganese steel, which can still be used when the quantity is less than the inspection standard. Under the working conditions of high energy impact, high manganese steel and ultra-high manganese steel castings have a wide range of applications. Many foundries lack the necessary knowledge about producing this kind of steel castings.
Extended data
Manganese steel is characterized by large solidification shrinkage and poor heat dissipation. Accordingly, the shrinkage of castings in process design is 2.5%-2.7%, and the longer the casting growth time, the higher the upper limit should be. The concession between molding sand and sand core must be good. The gating system is on.
A plurality of dispersed internal sprues are introduced from the thin wall of the casting, and they are flat and wide trumpet-shaped, and the cross-sectional area near the casting is larger than that associated with transverse sprues, so that molten metal can be injected into the mold quickly and smoothly, and the temperature difference in the whole mold can be prevented from being too large.
The diameter of the riser is larger than that of the hot spot, close to the hot spot, and the height is 2.5-3.0 times of the diameter. It is necessary to use hot risers or even pouring risers to make enough high-temperature molten metal to make up for the vacancy of castings during solidification and shrinkage. Put the sprue and riser in a high place (there are 5-8 sand boxes. ) is also correct. When pouring, pour as soon as possible at low temperature.
Once solidified, loosen the sand box in time. Smart designers are always good at using chilled iron, including inner chilled iron and outer chilled iron, which not only refines the primary crystal, eliminates shrinkage cavities and pores, but also improves the process yield. Of course, the appropriate dosage and specifications should be considered. The inner cooling iron should be clean and easy to melt, and the dosage should be less.
The functional relationship between the three-dimensional size of the external cooling iron and the three-dimensional size of the cooled object is 0.6-0.7 times. Too small won't do, too big will cause the casting to crack. Castings should be placed in the mold for a long time until the temperature is lower than 200℃ before unpacking.
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