Serving your country in our Armed Forces can be a great way to gain job skills, grow personally, build close friendships and see new things. That being said, the military lifestyle isn't for everyone - you will lose some of your personal freedom (when to wake up, when to eat, when to sleep, how to cut your hair, etc), you have to follow the orders of your superiors (if you don't, you could be punished with extra duty, loss of pay, restriction, etc), you may be asked to do things that you don't want to do (deploy somewhere for months at a time, go to war, etc), your pay may not be equivalent to what you could make on the outside. Our Armed Forces exist to protect and defend the United States, first and foremost - if you are not able/willing to do that, then there are other ways to become a welder.
So, the first question to you would be, "Do you want to serve your country?". Then, the next questions would be, "How do I want to serve my country?", "Do I want to be a welder in the Army, Navy, Air Force, Marines or Coast Guard?". If the answers to these questions are, "Yes!", then you should join on of the branches of the military as a welder.
I suggest you perform an assessment of what your career goals are against what your skills are. Develop a plan to improve your skills to match what your career goals are. Present this plan to as many people as you can and use their feedback to modify or improve your plan.
The navy has been a great career opportunity, I will say it depends on what you are looking to do with your welding skills. The navy has HT's(hull technicians) who weld but that is not their only job. As well as you are not guaranteed to get that school enroute to your first command. Joining the navy to do a specific task is usually a difficult challenge, you can always get close but just know nothing is guaranteed. On top of that, if you do get the job you want and the school to be able to weld and hold that position on the ship you also have to deal with a lot of other things to, maintaining your fitness, collateral duties, volunteering, outside education, other tasks with in the command. What you have to ask yourself is whether or not you want to weld for the navy and if you do you need to talk to a recruiter and research and look up everything they say. To verify you are keep in control of your future.