Rules for Heat Treatment of carbon Steel Castings. Con […]
Rules for Heat Treatment of carbon Steel Castings.
Considering the complex shape of valve castings, easy deformation and cracking, annealing is usually used for heat treatment of carbon steel castings.
The inspection shall focus on monitoring whether the supplier carries out the following heat treatment specifications and the hardness value of the castings.
Points for Attention in Heat Treatment of Carbon Steel Castings:
1. When the furnace temperature rises to 650℃~800℃, does it rise slowly?
Because in the heating process, especially for carbon steel castings with complicated shapes, when the furnace temperature rises to 650℃~800℃, the temperature should be slowly raised or kept at this temperature for a period of time. Because carbon steel undergoes phase change in this temperature range, with the volume change, phase change stress is generated. If the temperature rises rapidly, the temperature difference between the thin-wall part and the thick-wall part of the casting, as well as between the surface layer and the central layer, will easily increase, thus increasing the thermal stress of the casting and easily causing cracking of the casting.
2. Whether the heat preservation time is sufficient.
In order to make the internal and external temperatures of the castings consistent and have enough time to completely rotate the microstructure.
3. When annealing carbon steel castings, they are generally cooled with the furnace.
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