I see that you are saying 6417 rank in general category . This rank I won't say that it is good. But it is also not bad. 

And you want to get into IIT Madras regardless of which branch you get. Now if see previous year closing rank for different branch. You will get naval architecture and ocean engineering also dual BTech Mtech metallurgical branch.

So you better see which branch you want to go in. 

Thank you.