I think the correct answer is no. Calvinism includes something called "perseverance of the saints." Because faith is a gift, and God doesn't change his mind, if you are elect you're faith will continue to the end.
But salvation still requires faith. In the Reformed model it's not possible for someone to once be a Christian, fall away from the faith, and still remain saved, because if God chooses a person, he will make sure that their faith lasts. Someone who falls away shows by that fact that they aren't elect. Reformed would typically say that they weren't saved in the first place.
"Once saved, always saved" often has a slightly different meaning. It means that if you once meet the requirements for salvation, you're saved, even if you fall away completely. In my opinion once saved, always saved comes out of the free-will Baptist tradition. It's a remnant of perseverance of the saints, translated into an Arminian context.
There are probably people who hold Reformed perseverance and call it once saved, always saved, but I don't think they're identical.