Pro-Tec Coating Co., Leipsic, Ohio, a joint venture between United States Steel Corp. and Kobe Steel Ltd., has begun hot commissioning of the continuous annealing line supplied by SMS Siemag and installed at the works in Leipsic, Ohio. The line has been designed to produce almost 500,000 tpy of ultra-high-strength steel strips for automotive structural components. The annealing process and special cooling strategies reduce strain hardening from the rolling process, enabling the sophisticated mechanical properties in the material to be set exactly as required.
Besides the design and manufacture of the mechanical equipment, the complete electrical and automation package was part of the supply scope of SMS Siemag. The high-capacity annealing furnace with integrated ultra-fast cooling system was provided by Drever International, also a company of the SMS group. For particularly high cooling rates, which allow the manufacture of martensitic grades and ultra-high-strength multiphase steels, a water-quench system has been integrated as an additional feature. A further highlight is the nickel flash-coating system, which is used for coating the strip with nickel for special applications in the automotive industry.
The line has been designed for strips with gages from 0.6 to 2.3 mm and widths ranging from 700 to 1650 mm. The process speed is 140 m/min, whereas in the entry and exit sections 200 m/min can be attained. The grades to be manufactured are CQ, DQ, DDQ, EDDQ, HSLA and further AHSS grades (DP, MP, CP, BH, TRIP, MS).
Essential components of the line are two uncoilers, a welding machine, vertical entry accumulator, cleaning section, the Drever furnace, a water-quench system, pickling section, nickel flash-coating section, skin-pass mill, tension leveler, intermediate loop tower, inspection station, Doma-Bandzink oiler, flying shear, and two recoilers. The line layout makes provision for future upgrades in heating and cooling capacities, and the addition of a roll coater for post-treatment and of a side trimmer.
