Installation of three Castrip lines in one year to allow Shagang Group to produce green ultra-thin strip.
Ultra-compact and energy-effective Castrip plants had already been installed by Nucor in the United States of America, as well as in Mexico, when the Shagang Group introduced Castrip technology to China at its plant in Zhangjiagang, Jiangsu Province, in 2018. These new lines were all implemented in just 12 months, with the latest becoming operational in June 2024. Primetals Technologies is a licensee of Castrip and provides equipment and automation for Castrip installations.
Shagang uses Castrip to produce high-quality steel grades that, according to Primetals, meet the requirements of a wide range of applications and that normally consist of cold-rolled sheet. The Shagang Group has already granted the final acceptance certificate (FAC) to Primetals Technologies for the first two lines. In total, Shagang now operates four Castrip lines. The entire line is controlled by fully integrated basic (level 1) and process optimization (level 2) automation systems, which control all casting and rolling operations.
According to the company, Castrip is suitable for steel producers operating either electric steel mills or LD converters (BOF). Castrip plants are defined by highly flexible ultra-thin cast strip (UCS) production at the industry’s lowest energy consumption and emissions levels. Two main factors allow for this remarkable achievement – first, there is no need to reheat the strip, and second, Castrip lines produce strip of close to net shape, which lowers the amount of rolling force needed to meet product requirements. According to Primetals, this is why Castrip is an attractive alternative for steel producers looking to decarbonise the production process.
An uninterrupted process
During the Castrip casting process, liquid steel from the meltshop passes through two counter-rotating rolls producing a continuously cast steel strip. The ultra-thin cast strip (UCS) leaving the caster roll nip then enters an area of the plant with a controlled atmosphere, called the hot box. This sealed environment reduces the levels of oxidation and prevents excessive scale formation on the newly formed strip. Thanks to the hot box process, there is no need to descale the strip.
A Castrip line also consists of a single stand hot-strip mill, which reduces strip thickness by 10 to 55 percent. The hot-rolled strip then enters a cooling zone where a controlled decrease in temperature takes place which gives the strip the desired physical properties. In the next step, the strip is guided towards one of the two coilers, and a rotary drum shear is used to separate the strip, resulting in an uninterrupted process starting from the upstream area and continuing all the way through the Castrip plant. According to the company, Castrip is the ideal solution for steel producers entering the flat steel market, as well as for those looking for additions to their long-term product portfolio.
Castrip also works especially well for creating and producing special steel grades of various types – producers investing in a Castrip line can spare their hot-strip mill from producing demanding thin gauges and thus increase the output of the hot mill. Castrip steel sheet is used, for example, in the construction sector, for purlins, steel framing, steel decking, and racking/storage systems, as well as in the lightweight construction of items for the agriculture sector, automotive parts, and the welded tube industry. Ultra-thin cast strip (UCS) and hot-rolled coils are used as a direct replacement for cold-rolled products and can also be cold-rolled as thin as 0.25 millimetres to expand product ranges.
Source: Primetals Technologies
