METHOD FOR PRODUCING HIGH-STRENGTH ZINC-PLATED ANNEALED SHEET STEEL AND COMPLEX FOR PERFORMING THE SAME Russian patent published in 2008 - IPC C21D9/48 C21D1/76 C23C2/06 

FIELD: production of high-strength zinc-plated annealed sheet steel.

SUBSTANCE: method comprises steps of continuously annealing of cold rolled steel sheet containing 0.4 - 2.0 mass % of Si in double-phase ferrite-austenite temperature range 720 - 880°C inside tube-radiation type furnace for annealing in reduction zone; creating in said zone atmosphere containing 1 - 60 mass % of H₂ and also N₂, H₂O, O₂, CO₂, CO₂ and inevitable impurities, the balance; controlling in such atmosphere value log(PCO₂/PH₂) for partial pressure of carbon dioxide and partial pressure of hydrogen till value log(PCO₂/PH₂) ≤ -0.5 ; controlling value log(PCO₂/PH₂) for partial pressure of water and partial pressure of hydrogen till value log (PCO₂/PH₂)≤ -0.5 and value log (P_T/PH₂) of total partial pressure P_T, partial pressure of carbon dioxide PCO₂ and partial pressure of water PH₂ and partial pressure of hydrogen till range -3≤ log (P_T/PH₂) ≤ -0.5. After annealing sheet is cooled and coating of melt zinc is applied at continuous motion of sheet through galvanic bath in order to create on surface of cold rolled steel sheet layer of hot submersion. Then sheet is heated till 460 -550°C for alloying it.

EFFECT: enhanced efficiency of method, improved quality of zinc -plated sheet.

5 cl, 2 ex, 3 tbl, 2 dwg