The mass stabbing was carried out on a Doncaster-London train on the evening of November 1.
The driver made an emergency stop at Huntingdon, where armed officers swarmed the station in the eastern England market town.
One train worker was hailed as a “hero” after being critically injured as he stepped in to protect passengers.
Samir Zitouni, 48, suffered multiple injuries in the attack and was in hospital for two weeks.
Williams was also charged with affray and possession of a knife after a suspected incident at a barbers in Peterborough on October 31.
He faces a charge of assault of a 31-year-old man on a train travelling between Hitchin and Biggleswade on the same day.
Williams already faces another charge of attempted murder and possessing a knife after an alleged incident at a station in east London in the early hours of November 1.
-Agence France-Presse