In the selection of castings, it is usually recommended to choose stainless steel castings. The performance of stainless steel can be exerted in various equipment. Castings need to reduce many adverse factors in the production process, so as to improve the quality of castings. So how to reduce the internal stress of castings?
1. Reasonably design the structure of stainless steel castings.
The more complex the shape of the casting, the greater the difference in wall thickness of each part, the more uneven the temperature during cooling, and the greater the casting stress. Therefore, when designing castings, try to make the shapes of the castings simple, symmetrical, and uniform in wall thickness.
2. Adopt simultaneous solidification process.
The so-called simultaneous solidification refers to taking some technological measures to make the temperature difference of each part of the casting is very small, and solidification occurs almost simultaneously. Due to the small temperature difference of each part, it is not easy to produce thermal stress and thermal cracking, and the deformation of the casting is small. Try to improve the concession of casting mold and core, and set up the riser reasonably.
3. Aging treatment.
Aging is divided into natural aging, thermal aging and resonance aging. The so-called natural aging is to put the stainless steel castings in the open field for more than half a year to reduce the internal stress. Thermal aging, also known as stress relief annealing, heats the casting to 550-650°C, keeps it warm for 2-4 hours, cools to 150-200T with the furnace, and then comes out of the furnace. The resonance method is to shake the casting at its resonance frequency for 10-60ndn to reduce the residual stress in the casting.