Research And Development On 510L Black Steel Without Pickling Process

Acid free pickling technology is a process to treat the oxide scale produced on the surface of the hot rolled strip without acid pickling.In this process,the main phase of oxide scale is Fe3O4 whose structure is tight,and it will not drop from the steel plates during the stamping.Therefore,the downstream company can use the steel without acid pickling.The existence type,influencing factors and trancformation law of the oxide scale of hot rolled strip(510L automobile beam steel)are studied in this paper.Based on the simulated and experimental results of oxidation kinetics model and Fe O eutectoid reaction test,the second industrial trial was conducted,and the high level of acid free pickling black steel named 510 L was produced and met the demand of automobile industry.The “high temperature and fast rolling” process are determined as follows: the heating furnace tapping temperature is 1200?,the descaling pressure before rough rolling is 190 bar,the descaling pressure before finishing rolling is 160 bar,the outlet temperature of F7 stand mill is 880?,and the drift velocity is 13m/s.Meanwhile,based on the property analysis of the products,the property indexes of 510 L without acid pickling are stalbe and can meet the demand of the downstream company.The oxide scale of the steel plate without acid pickling have not dropped after the direct stamping.Its surface quality and property index are good and suitable for industrial production.