[USMCPOP]

Steel, concrete, whatever, it can be cut:

Abrasive saw
Plasma cutter
Oxy/acetylene torch
Air/arc gouging
Thermal lance

The latter is very simple and can melt through very thick steel, concrete and whatnot. Takes a bit of time but is used to cut very thick steel (feet). It requires a lot of oxygen but the rest is straightforward.

https://www.youtube.com/watch?v=rSpXJJ-ris8

https://www.youtube.com/watch?v=JI5whCBV0bk

https://www.youtube.com/watch?time_continue=3&v=na0NPbvD0Fo&feature=emb_logo

http://www.kandi.co.in/wp-content/uploads/2015/05/burning-lance-uses2.jpg

[USMCPOP]

These pieces of a ship engine crankshaft were cut with oxygen/acetylene torches, back in the day.

https://www.cca.org/blog/images/ship-building/Planingcrsfwebs1.jpg

http://2.bp.blogspot.com/_A4uX5rnqPEM/TMgx0wVMDFI/AAAAAAAAAhA/zUzCziYBbXc/w1200-h630-p-k-no-nu/Workshop5.jpg