Frank Vincent has been cremated and will be displayed at his memorial service ... TMZ has learned.

The body of "Sopranos" and "Goodfellas" star was taken to a Montclair, New Jersey funeral home.  After cremation, his ashes were placed in an urn. We're told the urn will be placed front and center on a table at the memorial service, surrounded by photos of the actor over the years.

As we reported, Frank died Wednesday due to complications from open-heart surgery.  

The service is Saturday.