Method and apparatus for cooling steel strip

In a cooling zone of a continuous annealing line engineered to continuously process longitudinally travelling steel strip, the strip is first slowly cooled to a desired temperature at a rate of not higher than 20 DEG C./sec. by means of a jet stream of cooling gas ejected against the surface of the strip and subsequently quenched to a desired temperature at a rate of not lower than 70 DEG C./sec. Thinner strip is quenched by high-speed gas-jet cooling that is effected by ejecting a jet stream of cooling gas against its surface, while heavier strip is quenched by bringing it into contact with the perimeter of cooling rolls cooled by a coolant. Namely, quenching is achieved either by high-speed gas-jet cooling or roll cooling depending on the thickness of the strip being processed. A cooling apparatus for implementing the cooling method described above comprises a high-speed gas-jet cooling zone where the strip is cooled by means of a jet stream of cooling gas ejected against its surface and a roll cooling zone following the high-speed gas-jet cooling zone where the strip is brought into direct contact with a plurality of cooling rolls. Means to exert longitudinal tension on the strip travelling through the roll cooling zone are provided at the entry and exit ends thereof.