I dont know why, the precipitation reaction that H900 produces wouldn't be affected by cooling rate from the precipitation temp. I dont know for sure but you also wouldnt want to carbonize (thats probabaly not a word) any oil onto the steel. (much like fingerprints on the steel before H900)
NickE, Israelkk,
Thanks for the response. I have never heard of oil quenching of PH steels and couldn't figure out why you would want to do it.
Someone new to my organization (not sure might be my boss some day) insists that he worked somewhere that did oil quenching. I'm just trying to:
a. figure out why
b. figure out if he knows what he is talking about.
The oil quenching would probably be from the solution treatment temperature, not the aging temperature.
With very large sections, there may be concern that air cooling from the solution treatment temperatures may not be rapid enough to prevent transformaton. I am not sure how large the section has to be for this concern to be valid, however. I know that air cooling is fine for solids up to 6 inch (150mm). I think it is more important that to cool it below 100 deg F.
I cannot remember the specifics, but I do seem to remember some specifications in the mid 1980's that called for air cooling or oil quenching from the solution treatment temperatures for 17-4.
While solutionising heavy section castings, as the cold air blast was insufficient to uniformly cool, I have water quenched ,immediately removed the parts from the tank and packed them in betwee ice blocks. Our being a tropical climate ambient temperature in the foundry will be 40 C + and not less.
