Science Buddies: "Ask an Expert"

I have a steel beam I'd like to corrode as quickly as possible.

I've tried salt, bleach and vinegar solution, and muriatic acid.
All produce surface rust, but I'd like to be able to corrode much faster, nearly all the way through.

Is that possible within weeks?
What would I use to corrode the steel in the fastest way possible? And hopefully safely?

I called up a friend who is a professional metallurgist and got some suggestions for you to look into.

- Crevice Corrosion (http://en.wikipedia.org/wiki/Crevice_corrosion) - The metallurgist thought this was probably the fastest way to see corrosion. Use a bolt or a washer on your steel beam to create a crevice where stagnant corrosive water can create a low ph environment. This would likely work in salt water or muriatic acid (HCl).
- Galvanic Corrosion (http://en.wikipedia.org/wiki/Galvanic_corrosion) - Create a galvanic cell using magnesium or zinc in salt water or muriatic acid.

A few other factors you may want to consider:

- Heat will increase the rate of corrosion. Be careful heating acids and don't use metal cookware on the stove - you will corrode the pot! Heat in glass and use caution.
- Stagnant water will increase the rate of corrosion.

Hope these help!

Audrey

It typically takes many many years for corrosion to compromise structural integrity. There are lots of sunken WWII ships that have structurally intact beams and plates.