Stress of Nickel Alloy and Its Relief Method

What is the internal stress of nickel alloys?

The internal stress of nickel alloys is due to the internal forces that interact between the various parts of the metal when the nickel alloy materials (such as plates, forgings, wires, bars, etc.) are deformed by external forces, humidity changes to resist this. The action of external factors, and try to make the object return from the deformed position to the position before the deformation. In addition, in the absence of external force, stress will also occur inside the nickel alloy material due to improper processing and forming, temperature changes, and other reasons.

What is the effect of stress on nickel alloys?

1. Cause changes in product size and shape. For example, when the Hastelloy B3 round bar has internal stress, the bar will produce corresponding elastic deformation or lattice distortion. If this stress disappears or its balance is destroyed for some reason, the corresponding deformation will also change, causing the bar to change in size and shape.

2. Shorten the service life of nickel alloy parts. Because the stress itself is balanced with each other, when an object with internal stress such as the Hastelloy B3 bar is loaded, it will cause uneven distribution of stress in the object. At this time, when the working stress reaches the yield strength of the material, the object will undergo plastic deformation; when the breaking strength of the material is reached, the object will break, thereby shortening the service life of the part.

3. Reduce the plasticity and impact toughness of the metal. If the Hastelloy B3 bar has internal stress, when it continues to be plastically processed, the existence of residual stress can strengthen the uneven distribution of stress and deformation in the object, so that the deformation resistance of the metal increases and the plasticity decreases.

4. Reduce the corrosion resistance and fatigue strength of metals. Due to the residual stress inside the part, it is in a high energy state, and it is easy to chemically react with the oxidizing medium, causing corrosion, that is, stress corrosion, thereby reducing the corrosion resistance of the part. The residual stress also changes the stress on the surface of the material when it is loaded. distribution, reducing fatigue strength.

There are several methods of stress relief:

1. Stress relief annealing is generally used to eliminate the internal stress of the metal, and the principle of stress relief annealing is as follows: when the stress relief annealing is performed, the metal is locally plastically deformed under the action of a certain temperature. Relax the residual stress to achieve the purpose of elimination. During stress relief annealing, the workpiece is generally slowly heated to a lower temperature, and then slowly cooled after a period of time to prevent the generation of new residual stress. Therefore, the reason why heat treatment can release stress is that heat treatment Allows local plastic deformation inside the metal to eliminate stress relief

2. Put it under natural conditions for elimination (ie, natural aging to eliminate internal stress). Natural aging: The component is placed in the open air, and after several months to several years of wind, sun, rain, and seasonal temperature changes, repeated temperature stress is caused to the component many times, and the residual stress is relaxed and the size is reduced. Accuracy is stabilized.

3. Vibration aging: This is a new method to eliminate residual stress, reduce deformation and maintain the dimensional stability of the workpiece. Can be used for castings, forgings, machining workpieces, etc. It is in the form of exciting vibration, adding mechanical energy to the workpiece containing a large amount of residual stress, causing the internal lattice dislocation to creep of the workpiece metal to stabilize the structural state of the metal, so as to reduce and eliminate the internal stress of the workpiece. No huge equipment is required economical simple and high efficiency. Spectral harmonic aging technology is a development on this machine tool, which can eliminate 60-70% of the stress and is very effective in stabilizing dimensional and shape accuracy.

Supplier of Quality Nickel Alloy

Wudenalloy has focused on the production and manufacture of nickel alloys for more than ten years. We are a principal worldwide supplier of corrosion-resistant alloys and other superalloy metals. We have a professional technical team and after-sales service, so we can offer high-quality Hastelloy, Incoloy, Inconel, Monel, Duplex Stainless Steel, and other alloy material. These materials are available in wire, bar, sheet&plate, pipe&tube, flange, forging, and other forms to meet the needs of our customers.

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