Quality-enhancing heat-treatment technology from SMS group
by Hans Diederichs
Nucor Corporation has awarded SMS group a follow-up order for the supply of reheat and heat-treatment facilities. The new equipment will be part of the new plate mill being built in Brandenburg, Kentucky. Nucor had already ordered the supply of a slab casting machine for the new mill from SMS group in 2019. “We are excited to be working with SMS group to have them supply critical equipment for our new plate mill in Kentucky, and to install their heat treatment line that utilizes the MultiFlex-Quench®,” said Johnny Jacobs, Vice President and General Manager of Nucor Steel Brandenburg.
The new casting machine will become the largest slab caster in the world. It will produce slabs of 200 to 305 millimeters thickness and up to 3,150 millimeters width. The follow-up contract now received by SMS group is for all of the new plate mill’s slab and ingot reheat equipment, for a heat-treatment line for heavy plate of up to 356 millimeters thickness and for a continuous heat-treatment line with MultiFlex-Quench® technology for plate between 4.8 and 102 millimeters thickness and up to 4,267 millimeters width.
Under the new contract, SMS group will supply a wide range of equipment, including: A walking-beam furnace for the transfer of slabs from the SMS group casting machine to the rolling mill. The furnace will be designed for slab direct, hot and cold charging. Slabs of the maximal possible length of 15,240 millimeters will be charged in a single row - shorter ones in two or three rows. As a highlight, the walking beam furnace will be fitted with SMS-ZeroFlame burners, which are characterized by extra-low NOx emissions. For ingot reheating, SMS group is going to supply bogie hearth furnaces. These furnaces will be able to reheat ingots of various sizes. The combustion process in all the reheat furnaces will be controlled by the proven, advanced SMS-PROMETHEUS® Level 2 technology.
Further to these supplies, SMS group’s contract volume includes additional bogie hearth furnaces and a quenching facility, which Nucor will be using for a wide range of heat treatments – from low temperature annealing through to normalizing. The connected quenching tank with water circulation will enable Nucor to precisely set the specific mechanical properties in heavy plate.
SMS group is also going to supply a continuous heat treatment line incorporating a MultiFlex-Quench®, which will be arranged downstream of the rolling mill facilities. A low-temperature furnace installed in the line will be used for plate tempering (warming-up). A specially designed gas recirculation system provides for optimal convection within the furnace chamber, resulting in maximum temperature uniformity.
The leveller integrated into the continuous heat-treatment line will be designed for plates of 4.8 to 25 millimeters thickness and a maximum plate temperature of 300 degrees centigrade. It will come with a roller actuation system that enables each levelling roller to be adjusted individually and the leveling strategies to be specifically tailored to the individual product. This assures minimum internal stresses and excellent flatness results. Thanks to the possibility of actuating all the rollers separately, optimum torque distribution is achieved.
SMS group will supply all equipment complete with the associated electrical and automation systems. This includes the motors and converters, all sensors and technological measuring systems, the complete Level 1 automation, and Level 2 process models. The process model for the MultiFlex-Quench® is one of the quality features SMS group will integrate in the heat-treatment line and which will play a key part in assuring the highest product quality.
Commissioning of the plant is scheduled for 2022.
Source and photo: SMS group