Selection of stress relief process for heat treatment of large gray iron casting

At present, the methods to eliminate stress in engineering include traditional natural aging, thermal aging and vibration aging.

1. Natural aging

Natural prescription is the oldest method of prescription. Relying on the power of nature, after months to years of wind, sun, rain and seasonal temperature changes, it has caused repeated temperature stress to the components for many times, reduced a small amount of residual stress, but improved the relaxation stiffness of the components. The dimensional stability of the components is good, the method is simple and easy, but the production cycle is long and the site is large, so it can not meet the needs of modern production.

2. Hot time simulation

Hot time simulation refers to slowly heating the workpiece to a lower temperature, holding it for a period of time to relax the metal, and then slowly cooling down to slowly eliminate the stress. The disadvantage of this method is that super large castings and alloy parts with strict temperature requirements can not be treated, and the energy utilization rate of this method is not high.

3. Vibration aging

VSR refers to that when the vector sum of residual internal stress and additional vibration stress in the workpiece exceeds the yield strength of the material through vibration, the material will have a small amount of plastic deformation, so as to relax and reduce the internal stress in the material. There are two kinds of vibration stress relief aging technology: traditional sub resonance technology and spectrum harmonic technology. This method needs to prepare different aging processes for workpieces with different shapes, and the operation is quite complex in production. The operator needs to determine the processing parameters for operation, but the effect of stress relief for complex workpieces is limited.

No matter what stress relief method is adopted, the internal stress of the casting can not be completely eliminated, but can only be partially removed, so as to eliminate its harmful effect. It is necessary to determine the stress relief process suitable for your own enterprise according to the casting size, size, requirements and the level of process personnel. Our factory mainly focuses on single piece and small batch, and the castings produced are selected to adopt thermal aging treatment process.

Scroll to Top