# Nitric acid and stainless steel?

**URL:** <https://boards.straightdope.com/t/nitric-acid-and-stainless-steel/688692>\
**Category:** Factual Questions\
**Created:** [May 18, 2014, 9:41pm UTC](https://boards.straightdope.com/t/nitric-acid-and-stainless-steel/688692 "2014-05-18T21:41:28Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Mdcastle](https://avatars.discourse-cdn.com/v4/letter/m/958977/32.png) [@Mdcastle](https://boards.straightdope.com/u/Mdcastle)\
**Post date:** [May 18, 2014, 9:41pm UTC](https://boards.straightdope.com/t/nitric-acid-and-stainless-steel/688692/1 "2014-05-18T21:41:28Z")

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Will 70% nitric acid dissolve stainless steel? I’ve got some steel screws and hinge pins stuck in aluminum with no other way to get them out, so was wondering it if was worth a shot or if I should just cut my losses and discard the items they’re stuck in. Already tried a screw extractor on the screw, and the screw was stuck so firmly that the screw extractor broke precluding any further attempts to drill it out. The aluminum around the hinge pins is so corroded I’d destroy it immediately if I tried to hammer the pins out.

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**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\
**Post date:** [May 18, 2014, 9:48pm UTC](https://boards.straightdope.com/t/nitric-acid-and-stainless-steel/688692/2 "2014-05-18T21:48:09Z")

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Are you trying to salvage the screws or the aluminum?

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**Author:** ![Mdcastle](https://avatars.discourse-cdn.com/v4/letter/m/958977/32.png) [@Mdcastle](https://boards.straightdope.com/u/Mdcastle)\
**Post date:** [May 18, 2014, 9:51pm UTC](https://boards.straightdope.com/t/nitric-acid-and-stainless-steel/688692/3 "2014-05-18T21:51:00Z")

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The aluminum

(I’ve also had college chemistry courses so I know how to safely work with the stuff…)

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**Author:** ![Nametag](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/nametag/32/406_2.png) [@Nametag](https://boards.straightdope.com/u/Nametag)\
**Post date:** [May 18, 2014, 10:07pm UTC](https://boards.straightdope.com/t/nitric-acid-and-stainless-steel/688692/4 "2014-05-18T22:07:40Z")

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It depends on the steel; some will dissolve, some will passivate. Screws aren’t usually made of the sort that passivates, I don’t think, but I’m not certain. Wouldn’t a disk cutter work? Or a torch?

And if it’s that badly corroded, what are you salvaging?

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**Author:** ![am77494](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@am77494](https://boards.straightdope.com/u/am77494)\
**Post date:** [May 18, 2014, 10:42pm UTC](https://boards.straightdope.com/t/nitric-acid-and-stainless-steel/688692/5 "2014-05-18T22:42:08Z")

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I would stay away from nitric acid because it will eat the aluminum faster than the steel.

If the screw is in an area where you can safely apply a small butane torch - I would try that. Here is one of them [http://m.harborfreight.com/http-www-harborfreight-com-micro-torch-42099-html.html?utm\_referrer=direct%2Fnot%20provided](http://m.harborfreight.com/http-www-harborfreight-com-micro-torch-42099-html.html?utm_referrer=direct%2Fnot%20provided)

The differential expansion between aluminum and steel might set it loose. Has worked for me but ymmv.