| 摘要 |
IN ORDER TO BE ABLE TO PERFORM THE MANUFACTURE OF DUAL-PHASE STEELS THROUGH CONTROLLED COOLING OF THE HOT STRIP IN TWO COOLING STAGES AFTER THE COMPLETED DEFORMATION EVEN IN THE EXISTING COOLING LINES OF A CASTING AND ROLLING FACILITY HAVING THE LOCAL CONDITIONS, IT IS SUGGESTED ACCORDING TO THE PRESENT INVENTION, BESIDES KEEPING THE CHEMICAL COMPOSITION OF THE STARTING STEEL WITHIN PRECISELY DEFINED LIMITS, THAT THE TWO-STAGE COOLING BE PERFORMED FROM A FINAL ROLLING STRIP TEMPERATURE T FINISH WITH A3-100 K< T FINISH <A3-50 K TO A COILING TEMPERATURE T COILING <300°C(<MARTENSITE STARTING TEMPERATURE ). THE COOLING SPEED V1,2 IN THE TWO COOLING STAGES BEING BETWEEN V-30-150K/S, PREFERABLY BETWEEN V-50-90 K/S, THE FIRST COOLING STAGE BEING PERFORMED UNTIL THE COOLING CURVE ENTERS THE FERRITE REGION AND THEN THE CONVERSION HEAT RELEASED BY CONVERSION OF THE AUSTENITE INTO FERRITE BEING USED FOR ISOTHERMAL HOLDING OF THE STRIP TEMPERATURE T CONST. ACHIEVED, WITH A HOLDING TIME < 5 SECONDS UNTIL THE BEGINNING OF THE SECOND COOLING STAGE . |
