My 3 & 1/2 cents worth
When you talk about Alcoa & US steel - you are look at large lifts - 12 to 30K - very special units & you need a BIG check book. I would steer away from those unless you ca have connections that can get you the business. These companies are typically National Accounts buyers And there is something to be said for renting units of the same brand you are using - operator familiarity.

Just a suggestion start with the IC trucks cushion & pneumatic 5-6000 lb, lift range, 189" triple, side shift - forks 42", 48" and grow from their until you find what the "dogs eat). Electric lift are common with food companies like Heinz but require more investment dollar (battery/chargers plus the lift). It takes some time to learn what chargers you may need & which ones to avoid.

You will be competing with all the other brand lift truck companies in your area plus the independent lift truck companies, plus rental yards like Sunbelt Rentals, etc
Suggest you review your market needs, pricing ( published rental rates are probably not a good indicator of market pricing), etc before you commit. Current companies in your area probably are not a good source of G2 they don't really want another competitor in the area. Besides equipment you will need to have some structure to have your assets, serviced, repaired, etc. Documentation (rental contracts, operators manual, etc.) & record keeping system are key items, following up on & determining abuse damage are other key points. Check out the cost of liability insurance too! Oh yeah, you'll need a delivery truck & licensed driver with tilt bed (for ground loading where a customer does not have a loading dock access. There is a lot more to know about the rentals business.