QRO 90 Weld coated electrode and QRO 90 TIG-Weld filler rod are especially composed to be compatible with these Uddeholm hot work steels: ORVAR (all grades), QRO 80 Microdized and QRO 90 Supreme. This datasheet provides information on composition and hardness. It also includes information on joining. Filing Code: TS-508. Producer or source: Uddeholm Corporation.