Simultaneous patenting and pickling of hot rolled steel - in molten caustic soda contg. sodium hydride

摘要

Hot-rolled steel wire rod, intended for drawing operations, after leaving the rolls at 1000-1050 degrees C. is intermittently water-cooled on its surface to 650-700 degrees C. in steps sepd. by stages permitting heat to travel from the core to the surface so a rod temp. of 650-750 degrees C. is reached and the rod, at just below the Ac3 temp., is continuously cooled in molten salt at 350-500 degrees C., the salt having reducing properties; the individual loops of rod are exposed to intensive circulation of the salt for the simultaneous achievement of the optimum structural transformation for drawing with surface pickling, and the coils are then washed to remove salt and for cooling to ambient temp. Continuous process eliminates a separate pickling operation, thus reducing costs.