Nitriding+post oxidation+passivation on medium carbon steel bar

[gma301221]

are there any ASTM or AMS standard for all three processes? Aware of AMS2759/8 for plasma nitriding.
Looking for industry standards for post oxidation and passivation.
I found literature on post oxidation after plasma nitriding and its benefit in improving corrosion resistance.
A heat treat supplier is suggesting Nitriding+ post-oxidation+ passivation on 1045 steel.
Not sure what is the purpose of doing passivation on 1045 steel? Any idea or any literature anyone can recommend.
Most often passivation is applied to stainless. Looking for any industry standard available for the two processes after nitriding.

 

[mfgenggear]

Material normally used is nitraloy 135 steel. Standard nitriding AMS2759/9 gas nitride,. But creates white layer which is very brittle.and will chip easily. White layer can be controlled with 2 stage gas nitride or plasma nitride. Post chemical etch to remove white layer. It is not passivation.

 

[gma301221]

mfgengear: this is plasma nitriding of 1045 steel which is given post oxidation and passivation treatment to improve wear and corrosion resistance.
Not sure why passivation? i am aware of Ams2759/8 for ionic nitriding although it does not outline any post nitriding treatment with oxidation.

 

[mfgenggear]

Nitrided stainless is passivated before nitriding, low ally steels are never passivated. 1045 is not a nitriding steel. But it can be nitrided, but the case depth will be shallow. Nitraloy is made for nitriding. It can have a deep case.

 

[EdStainless]

There are a bunch of easily nitrided alloys similar to N135M, they usually contain Al.
You acid etch the white layer off of these parts much like you etch the brittle oxide layer off of heat-treated Ti parts.

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P.E. Metallurgy, consulting work welcomed