Category Archives: Training
History of Ion Nitriding
The history of ion nitriding dates back to its birth in 1932. A German physicist, Dr. Wehnheldt, was the first to develop ion nitriding; however, he was unable to control the glow discharge. By teaming up with the Swiss physicist, Dr. Bernhard Berghaus, they were able to develop ion nitriding into a usable, stabilized process. After WWII, electronics, plus the need for more superior metallurgical properties, contributed to increased popularity of ion nitriding among American industrialists. Dr. Claude Jones, Dr. Derek Sturges, and Stuart Martin helped advance ion nitriding in America by applying the process to a variety of parts as well as building the first ion nitrider in the U.S. As success stories filtered through American industry during the 1980’s, ion nitriding became a respected, preferred process for many manufacturers. Today, ion nitriding remains a favored heat treating process, and it continues to develop as the industry pushes for even more efficient, economical and environmentally safe heat treating process.
Case Depth Terms
When applying a heat treatment, such as ion nitriding, to a part, it is important to know the following case depth terms:
Effective Case Depth (ECD):
The distance from the surface of a hardened case where a specified level of hardness is maintained (typically 50 HRC eqv.).
Total Case Depth (TCD):
The distance from the surface of a hardened case to a point where differences in physical properties of the case and core are no longer distinguished (visual or hardness method).
For example:
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Ion Nitriding Frequently Asked Questions
Will my part have any growth and/or shrinkage from UltraGlow® Ion Nitriding?
Generally, your parts will have minor growth depending on the process that you are requesting. The growth will be dependent on the amount of compound zone (white layer) that is required/achieved during processing. The standard rule of thumb is ~70% of the CZ Layer thickness.
How does AHT know that my parts met the right hardness and case depth specified?
When processing your parts, an AHT sample of similar material and/or customer supplied sample will be processed with the parts. After processing, a full metallurgical evaluation will be performed in order to document the results achieved.
What will happen to parts that I have repair welded?
The weld repair should nitride dependent on the material. If you have made weld repairs, it is imperative that you provide the welding material to AHT prior to processing as it may respond different to nitriding than the base material(s).
I have heard of UltraGlow® Ion Nitriding but do not know exactly what it is?
The process is conducted in a vacuum chamber back-filled to a very low pressure with a mixture of nitrogen and other gases. A high voltage electrical charge forms plasma from the gas mixture. Nitrogen ions then accelerate through the plasma and impinge on the workpiece. The ion-bombardment process heats the workpiece, cleans its surface, and results in absorption of active nitrogen into the surface of the material producing a “hardened case”.
How long does UltraGlow® Ion (Pulse Plasma) Nitriding take?
Due to the various materials and/or requirements the UltraGlow® Ion (Pulse Plasma) Nitriding process can take anywhere from a few hours up to a few days.
What do I need to do to my parts after UltraGlow® Ion Nitriding?
UltraGlow® Ion (Pulse Plasma) Nitriding is generally performed on “finished” machined parts. After processing, a light polishing of the part(s), if required, will bring your part back to the required surface finish with no affect to the nitrides.
What information do you need before you can quote/process my parts?
At a minimum, we need the following information:
• Material/Steel number
• Type of heat treat requested
• Surface hardness
• Case depth
You may also include the following additional information:
• Core hardness
• Selective location for heat treat
• Any previous heat treat/thermal processing on parts
When is carbonitriding better than carburizing?
Carbonitriding (CN) is a very effective case hardening process, and it can be used on a variety of low carbon steels. CN is well suited for sheet steel and 10xx, 11xx, and 12xx series steels. The addition of nitrogen to the case hardening process allows the case hardened layer to react and form a harder case than would typically be provided with carburizing alone. The CN is also a lower temperature process, which can contribute to lower distortion.
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