how does copper stop heat treating

[kenre]

As the question says,. Have seen parts made from unknown steels that are copper plated, and soft, but hard where there is no plating.

Ken

 

[Carburize]

Copper is sometimes used as a "stop off" to prevent carburizing.

 

[arunmrao]

Copper is selectively applied to some regions in a component to retain the original characteristics. The unplated regions are carburized . Copper acts as a diffusion barrier and thus protects the base metal.

 

[unclesyd]

Copper is commonly used as a stop off when nitriding metals. Copper will completely stop the diffusing of Nitrogen in metals during a normal nitriding cycle.

 

[kenre]

Ahh i think i understand now.
So it has no effect with a normal heat treat? only when carburising or nitriding?

Ken

 

[TVP]

Copper prevents the diffusion of O or C during elevated temperature processing. During "normal heat treat", it will do the same thing as during a carburizing or nitriding cycle-- prevent the diffusion of O or C into or out of the steel. It is not usually used during normal hardening and tempering because atmosphere controls are used for excluding oxygen and maintaining the proper carbon potential in the furnace.