Bom Dia Giovanni,
We do have many companies that make pastes and gels to remove heat tint and scale from the weld zone here in the U.S. Avesta is my choice for products here. The best I have found though, is in Brasil, a company called D Sanctis & Mereiros Associados, they are in Sao Bernardo.
Many good things in Brasil, people, samba, picchania, carniera, cerveja, pinga etc! I like your country very much!
Abriggado, Brad