cost of carburising and carbonitriding

[limct]

If we disregard the case depth, but to have the case hardness controlled at HV 450 min. and core hardness at HV 270~390 for a part made of low carbon 1018/1022. which of the process will cost less? gas carburising or carbonitriding? and why?

Best regards,
ct

 

[unclesyd]

Carburizing will cost less as it is normally just an atmosphere control. Carbonitriding is normally more expensive due to having to have an atmosphere containing N2, usually from disassociated NH3. This is a very general statement so I would recommend you get quotes from the heat treater as to his capabilities and quantities he can handle. If your quanity is small he could piggyback your parts with others and you should get a price break.

You will be hard pressed to get the core hardness you require with either of these materials unless the cross section is less than 1/2". The case hardness will generally be quite higher than you desire on either material

Come back with a little more information as to part's dimensions.

 

[limct]

Thanks Unclesyd, I guess it'll not be an issue to control the core hardness in this case, as I'm only refering to small screws (<M8).
If we assume 1 to 1, say the quantity it's big enough to occupy the full capacity of one heat treatment line in one run, how much roughly in percentage will the parts' cost (treated through these two different processes) be different from one another?



Best regards,
ct

 

[unclesyd]

Again it depends on the heat treater and how his furnaces are set up. If he does a lot of carbonitriding of small parts the adder for the carbonitriding should be 15%-20% over carbonizing. If you have the quantity any shop should give you quote.

A note of caution on carburizing or decarburizing on of fasteners. If the fastener is fatigue application carburization or decarburization of the fastener can greatly reduce the fatigue life of the fastener.

If you need a harder or stronger fastener I would suggest changing the material instead of carburizing or carbonitriding.