Could PVD coating cause surface tempering?

[coreman73]

I have a snip blade cutting tool that appears to have been (based on EDS results) plated intially with a pure Ni layer which was then covered by a second layer of TiAlCrN (most likely by PVD process). The surface hardness of the snip blade was induction hardened to 60-62 HRC.

It's my understanding that PVD coatings have a deposition temperature of around 700-800 degrees F. My question is how could this second layer have been applied without negatively affecting/tempering the below Ni layer and underlying Fe base metal?

I would very much appreciate any input.

 

[metengr]

Have you evaluated or are considering a coupon to confirm if PVD process duration can actually temper the surface?

 

[coreman73]

metengr,

We haven't considered doing this yet but it's a good idea.

The chemical analysis results of the base material seem to indicate 1060 steel grade was used. However, there are additions of Si (.28 wt%), Cr (.23 wt%) and Mo (.20 wt%). Could it be possible that this is some sort of modified steel that requires a tempering temperature to be high enough so that the PVD process wouldn't affect it?

 

[metengr]

coreman73;
I am going to be as straight forward as possible regarding advice, and not guess or assume anything. When it comes to anticipating what may happen because of a particular process, what better way to do this by using sample coupons to confirm your findings. The cost is relatively inexpensive, and it can be defended.

 

[coreman73]

metengr,

That is very true and agree. I will go ahead and recommend that the engineers take a sample and try this out for themselves. By the way, this is some reverse engineering that's being done so it's pretty much all going to be a guess anyway.