17-4 forged material

[forging82]

I was wondering if anyone knows how high 17-4 material can be heated during solution without growing grain size. I know the recommended temp is 1900F but I'm wondering what will happen if the furnace is hotter(~1970F).
Thanks

 

[TVP]

Do you know what the original forging temperaure was? If it was higher than 1970 F, then grain growth should not be an issue.

 

[forging82]

They were forged at 2175F.