Quench discoloration question

[i4Marc]

I just quenched this blade. It is in sub zero bath right now. Is this bad? Do i need to be concerned? The blade is A2 (Aldo) 1/4" at the spine. Plate quenched between two 6061 2x4s. Austenitized @1750˚. That wasn't the whole HT routine but that's the temp from which I quenched. The SS envelope the blade was in had nice tight folds. I did not use a combustible inside the envelope.

 

[DevinT]

That is a leak in the envelope, nothing to worry about.

Hoss

 

[i4Marc]

Whew! Thanks. I tested the areas with a file and it skated very easily.

 

[Stacy E. Apelt - Bladesmith]

As Devin said, it is no concern. Usually caused by a minute leak in the foil packet, or by oils and stuff in on the blade. You can get rainbows, blotches, colors, etc. None are a worry if everything else was done right.