Thread: Can you checmically alter/affect temper?

I'm here. Charlie's right, drawing the temper back too far will require temperature, usually above 400F, but the exact temperature will depend entirely on the steel. If we're talking about an ordinary carbon steel, as long as you stay below 400F it should not lose any hardness.

That's how some of the chemical bluing is done and the temperatures are held at or below 300F so the risk of affecting the hardness of the steel is nearly non existent.

If you treat this with a steel eating acid, whatever steel is left that's clean should be the same hardness you started out with. You are only removing superficial oxides (rust - crud) anyhow.

DISTRACTION alert: You could investigate hydrogen embrittlement. As acids are Hydrogen linked to some other compound. Hydrogen can make steel more brittle. And hydrogen is small enough to find its way between the iron carbide lattices.

Prahston: I posted that distraction for those folks here that I know will not sleep well until they have chewed this mental beef jerky down to the atomic level. This does not affect your concern about your blade. OTOH if you are easily distracted by the distraction, you are very likely to find yourself in good company.