steel? who cares, i'm using it on carbide toolsI would stay far away from HCl. It reacts with the steel also. The worst part is hydrogen embrittlement. You won’t know it’s there till your tool snaps the next time you use it. Hydrogen in the acid will migrate into the iron matrix of your tool causing enormous localized stresses.
Can be cured though. Just heat in an oven @350°F for an hour and the hydrogen will migrate out of the tool.
Alkali will attack the aluminum. Acid will attack steel.Draino is lye with aluminum chips mixed in. Add water and the aluminum reacts fast as it neutrilaizes the lye. So an overnight soak in draino is not going to do much after 15 minutes. Overnight in lye water will keep reacting until all the aluminum is gone or the lye is all used up.
Do not do this in plastic tubs or glass that can not stand the heat.