Can I translate scientific papers ? So I'm a really bored french student and there's a thought that occurred to me of something that could kill three birds with one Stone : improving my English, allowing me to learn New things and making research more broadly available to the ones who are interested in them but are blocked by the language barrier.
And this is translating articles or papers of researchs or studies in french. I would guess that there's not really anything preventing me to do that for personnal use, but what if I wanted to, as I stated, make the translated versions available on a website or a database ? What should I know about that or what should I do in order to meet both the legal and ethical requirements of such a thing ?

Thanks in avance for your answers.
Ethically, I do not see a problem with this. If you reference the original work and make it clear that it is translated then I think it should be fine.

The problem here is from a copyright point of view. Many journals are subject to copyright and if you post the findings online then someone could not pay to read the documentation and just go to your website and then translate it into whatever language they wish. 

I must mention that even though you think you're doing something that benefits others, without even making profits, you can still be in trouble. 

If you're really interested in translating a particular piece of work you would need permission from both the author and the publisher (if you're going to publish it online). 

My advice would be to ask permission from authors who have unpublished work. An example in finance is John Cochranes guide to PhD writing, this was translated from English to Chinese and placed on his personal website with credit given to the translator. 

This way, you don't get in any trouble and you are still gaining the benefits of translating that you mentioned in the question.