I was recently divorced, in my divorce papers I legally hyphenated my name to my maiden name-married name keeping the latter name because of small children. My question is: can I legally use only the first portion (maiden name) alone when changing my credit cards and work ids and bank accounts?

You can ask people to call you what ever you want at work but for any legal type document such as bank accounts you have to have your full legal name. As for work ids it is more company policy, for your payroll and employee info they will need your full name but could probably leave off half of your last name for you id, again that is all upon company policy.

You can ask the banks to do this, but since it is not your legal name now, I doubt if they will.