As a 91E welder and machinist, what would I be doing on a deployment? Any chances for some combat?

SPC (Join to see) I have no problem volunteering for new experiences and opportunities, but be careful what you wish for. Combat is not something to wish for. Good luck.

Welders are in demand to fabricate and fix things like the perimeter, culvert denials, and other things around the FOB. You will most likely be on a FOB. When you do go out on missions you will most likely pull security or if you are qualified, pull up the rear in a wrecker in case somebody hits an IED or breaks down. Otherwise yu’ll Remain on the fob and fix vehicles and infrastructure.

It all depends on your exact location, unit mission, and Chain of Command. Depending on where you're at you may pull gate guard from time to time, but unless your unit or someone they are attached to needed some extra hands I don't know how volunteering would work.

Again, depending on other factors, you may travel from point "A" to "B" or be somewhere that falls under attack. In my experience, you would be far better served by taking your combat training seriously and being ready if something were to happen rather than having high hopes of seeking it out.