Heat treat scale

Thin ground blades, off ground blades can distort during heat treating, as well have oxide/discoloration from my argon furnace. Typically the finish left from heat treating is easily removed with 220 grit.The image above is characteristic of what comes out of my furnace. Left side of the blade is after being ground with a A65 3M™ Trizact™ Gator belt.

Various reason for wrapping exist such as asymmetrical grinding - excess grinding/machining stresses, overheating during machining operations, welding or previous thermal treatments.

Stress cracks can occur for a number of reason, some are due to sharp corners, holes not chamfered, material faults.
Some deformation should be expected in virtually all blades. While the above is a rare occasion and I can straighten, I am not able to guarantee the straightness results nor replaced damaged product/material, if required to straighten.