Solution Annealing Austenitic Stainless

[leebeard]

Sometimes our direct resistance heating is non uniform when solution annealing 304L and 316L stainless, Our temperature range is 1900 - 2000 F. My questions are: Is their a maximum temperature that should not be exceeded? (2) How long should our part stay in the Solution annealing range. (3) How fast must it be cooled to keep from developing chromium carbides while cooling.

Thanks,

Lee

 

[unclesyd]

Get there and get out of there fast, the faster the better.

I don't know the current thinking on the upper limit but I have always used 2350°F with essentially no time at temperature. If there was going to be appreciable a time at temperature due to handling we have brought our temperature down to 1850°F with 2 minute soak.

Water was the preferred quenching media. When using air, or air/water, we like to get under 700°F in less than 5 minutes or faster.

A slow heating rate isn’t good as you can end up with excessive grain growth.

Are you a mill heat treating a product or a fabricator heat treating a fabrication?

 

[EdStainless]

I don't like anything above 2250F, grain growth and scale formation are both killers. Though you need to hit 1850F min.
Are you running low carbon material?
For straight grade I like to get below 800F in 3 min.
Good low C material you have double that time.

Syd is on the money, the faster the better. Both heating and cooling. If you can't cool with water then it should be forced air.

And watch out for arcing at your contacts.

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Corrosion never sleeps, but it can be slowed down.