GALVANNEALED SQUARE STEEL TUBE

• Main Authors: ODA TAKAMASA, ANAI ISAO, TAKACHI TSUTOMU, HIROSHIGE ITSURO, NIISATO FUMIAKI
• Format: Patent
• Language: English
• Published: 10.10.2000
• Edition: 7
• Subjects: CHEMICAL SURFACE TREATMENT; CHEMISTRY; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY IONIMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; DIFFUSION TREATMENT OF METALLIC MATERIAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS; METALLURGY; MOTOR VEHICLES; PERFORMING OPERATIONS; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; TRAILERS; TRANSPORTING

PROBLEM TO BE SOLVED: To provide a galvannealed square steel tube whose mechanical strength is compatible with corrosion resistance. SOLUTION: In the galvannealed square steel tube applied with a chemical conversion treatment and a coating after forming a galvannealed steel sheet into the square tube, corner parts R are made to have a thickness of 2-5 times of the steel sheet thickness (t). In this way, the crushing of crystal on the surfaces of the corner parts in the galvannealed steel sheet is prevented and the crystal in the chemical conversion treatment film on the surface of the corner parts and the coating can intensely and closely be stuck on the surfaces of the corner parts and vicinity thereof with an anchor effect.