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Plasma ion nitriding plus cryogenic

Dear Sirs,

Is it necesary to harden the steel before doing plasma ion nitriding to reduce the hardness difference between the surface and inner core.

Which of the following will give better surface:
Hardening+PIN+Cryogenic or Hardening+Cryogenic+PIN

Regards

Raja Sundaram
consultant - Coimbatore, Tamilnadu, India
2004

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2006

Dear sir,
I want to know how and why ion nitriding is better than gas nitriding..

regard..

Noorul Hidayah Shaiful Alam
University Technology Malaysia - Skudai, Johor Bharu, Malaysia

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2006

Dear Noorul,
Plasma Ion Nitriding(PIN) scores over gas nitriding and other conventional nitriding in the following areas:
· Lower processing temperatures: This factor signifies lower dimensional distortion and more control on the formation of undesirable metallurgical phase.
· Almost zero contamination: With the use of vacuum, chemical contamination due to the presence of atmospheric oxygen, moisture of hydrocarbon etc. is eliminated.
· Faster treatment cycles: PIN cycles may be as short as 15-20 minutes or 6 to 8 hours on an average compared to the 80 to 100 hours required by gas nitriding.
· Total control over the nitrided case: All conventional nitriding processes call for an additional lapping/grinding operation to remove the brittle 'white layer'. In comparison, PIN is the only nitriding process, which offers total control over the composition of the nitrided case.
· Lower Costs: Due to shorter treatment cycles, greater reproducibility and an almost zero rejection rate due to tight process control, PIN works out much cheaper. PIN can act as a final hardening cum finishing operation, thereby reducing manufacturing costs and can replace costlier materials used conventionally.
· Augmenting the metallurgy: In high wear rate components such as mining, earthmoving or construction equipment. PIN can raise surface hardness from 65-68 HRC obtained traditionally to 72 plus HRC at a small extra cost.

Raja Sundaram
- Coimbatore, India