Gas Nitriding Service

For gas nitriding, our Ohio facility is well located for Midwest manufacturers, offering one of the largest nitriding departments in the country. CST’s Ni-Surf process for gas nitriding is a contemporary multi-stage procedure for case hardening alloy steels such as 4140 and 4340, special nitriding grades such as Nitralloy 135M, and tool steels such as D-2, H-13, and S-7. It produces a high surface hardness for excellent wear resistance, improved fatigue strength, increased corrosion resistance, and a surface that is resistant to softening from elevated temperatures up to 1000°F.

Since the gas nitriding process is performed at low temperatures and quenching is not required, size change and distortion are very minimal. Parts are typically core treated and finished machined prior to nitriding, with some allowance being made for a slight amount of growth. Unlike nitriding methods using a salt bath, gas nitriding is a more flexible process with easier disposal of the nitriding agent.

The following table lists the typical properties produced by CST’s standard Ni-Surf process. Special cycles are employed for deeper case requirements. Parts up to 57 in. in diameter or 107 in. can be accommodated. Standard cycles are started frequently to ensure excellent turnaround.

Typical Properties Produced By CST’s Standard Ni-Surf Process
MATERIAL	CASE DEPTH	SURFACE HARDNESS
4140-4340	0.016-0.020 in.	86-88 HR15N (50-56 HRC)
Nitralloy 135M	0.010-0.013 in.	93-96 HR15N (67-70 HRC)
D-2 Tool Steel	0.008-0.010 in.	92-94 HR15N (64-69 HRC)

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