We have a need to make some very flat plates from hardened 17-7 PH stainless.  The problem we're having is that the plates are ported and ground flat and parallel within 0.001", and we must have a final hardness of around 42Rc.  We've already failed on one batch, where we ended up with the plates warped about 0.010".  Does anyone have a suggestion for order of processes, figuring they need to be ported out, ground flat, and heat treated?

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I think > 6 mm when I see the word plate so I seriously doubt that the laser cutting had much of an influence on part warpage unless the thickness is quite small.  One sequence would be to rough cut everything in the solution annealed condition, then age to the desired strength/hardness, followed by finish milling or grinding.  Unless you need to make large quantities of these parts, then I would not worry about the reduced machinability of 17-7 PH in the aged condition.  With today's tool technology, hard milling can be quite effective, likewise with grinding.

Start in Cond A or C, do you think?  Also, the ones that ended up not flat were lasered to give us the porting.  There's some thought here that perhaps the heat from the laser cutting caused some warping, so we thought maybe water jet next time.

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