How much do you know about the aging treatment process of valve castings?

The treatment process for eliminating internal stress of valve castings is called aging treatment: natural aging, artificial aging and resonance aging.

(1) The natural aging of valve castings is to place the castings in the open air for several months, half a year or more than a year, so that the castings deform naturally and slowly, so that the residual stress is gradually eliminated by itself. The natural aging period is long, and the internal stress is not completely eliminated. For example, only 30% of the residual internal stress can be eliminated by placing it for six months, which is rarely used in production. Therefore, artificial aging treatment is often used to eliminate casting stress.

(2) Resonance aging treatment Under the action of the periodic external force of the exciter - the exciting force, resonance occurs with the casting, so that the valve casting obtains a considerable amount of vibration energy. During the resonance process, the alternating stress and the residual stress are superimposed, resulting in local yielding and plastic deformation, so that the residual stress in the casting gradually relaxes and disappears, so as to achieve the purpose of stabilizing the casting size. The maximum benefit is obtained when the dynamic stress is close to 35MPa. Generally, a dynamic stress of 20MPa can be used to obtain satisfactory results. Resonance aging is an advanced method that saves time and energy.

(3) Artificial aging treatment is to heat the casting to the temperature range of the elastic-plastic state of the alloy, keep it at this temperature for a certain period of time to make the stress disappear, and then slowly cool it to the temperature range of elastic deformation, and cool it out of Stainless Steel Silica Sol Casting Customization Pipe Fittings Casting Parts the furnace. Artificial aging is usually carried out after the rough machining of the part, which eliminates the original residual stress of the casting and also eliminates the cutting stress generated during the rough machining process. There are also some valve castings with high precision requirements, which are artificially aged once before roughing, and then artificially aged again after roughing.