Partial Protection of Ion Nitriding

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There are many things to pay attention to when ion nitriding of parts. Ignoring them will bring difficulties to the operation and make it impossible to proceed, or the quality of nitriding does not meet the predetermined requirements, and more seriously may cause parts and equipment to be scrapped. Damaged. In the following cases, local protection is required before ion nitriding.

1. Meet the mechanical performance requirements. When subjected to external forces, some parts of the part that produce stress concentration may encounter unbearable peak stress, and the peak stress cannot be reduced through local plastic deformation, thereby prematurely forming cracks. Therefore, the parts that are prone to stress concentration should be protected when nitriding. Such as threaded holes and oil holes on parts such as high-load shafts and crankshafts. In addition, only through plastic deformation can the full-loaded mechanical connection components (threads, etc.) be reached; the parts with complete penetration risk (thread teeth, heat dissipation flanges, etc.); have different metallurgical phases and materials, and these structures or alloys have nitriding The parts that tend to become brittle later or have different nitridability (welding seams, inserts, etc.) and surfaces that are at risk of thermal cracking when subjected to temperature shocks also need to be protected.

2. In order to reduce deformation. If the nitriding is limited to the required position, the resulting size change does not exceed the allowable range, which can save the grinding process after nitriding.

3. Processing after nitriding. After nitriding, some parts that require a soft surface must be processed. For the purpose of installation, calibration and measurement, the cutting process (except for grinding) needs to be prevented from nitriding.

4. Some parts that are prone to glow concentration and can not be nitrided need to be shielded, such as narrow grooves and small holes on the parts.

The method of realizing partial nitriding basically uses steel covering shielding and mutual shielding method of nitriding parts in China. This is a completely technically satisfactory surface shielding method based on the special dynamics of ion nitriding. The protective effect can be obtained by inserting and screwing in the place where nitriding is not required, and covering or covering with steel parts of suitable shape and size. These shielding parts can be standard parts, such as pins, screws, jacks, nuts, etc., or special shielding parts such as boxes, covers, sleeves, etc. can be designed and processed according to the shape and size of the nitriding parts that need to be shielded, or the parts do not need to be used. Nitrided surfaces touch each other to shield.

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