A new industrial process allowing to reach very high cooling rates in the cooling
section after soaking of a continuous annealing line for steel sheets is presented.
This process constitutes the successful conclusion of a long term research programme,
jointly carried out at CRM and Arcelor Cockerill-Sambre for three years, including
laboratory experiments, pilot scale trials and several industrial campaigns. It is
running on from developments performed in the framework of the HOWAQ (Hot Water Quench)
process. The process successively combines a moderate cooling step (600 °C/s
for 0.8 mm thick strips), in boiling water, and a faster cooling step (above 700 °C/s), by impinging
turbulent cold water in a box. Its main features are simplicity, resulting from advanced
developments, soundness, flexibility and cooling homogeneity. As treated steel products
are characterized by improved mechanical properties, outstanding surface quality
(corrosion resistance) and exceptional flatness. The process is implemented industrially
since the beginning of 2002.