JISCO rolling mill successfully finished smelting 70 tons of high manganese non-magnetic steel ordered by a user in Xi’an. 2020, the product has been supplied to 375 tons for downstream users.
High manganese non-magnetic steel has the advantages of stainless steel resistance to low-temperature impact, low magnetic non-magnetic, and the advantages of excellent mechanical properties of carbon steel, easy to weld and other processing properties, and is widely used in the manufacture of large transformers internal structural parts low magnetic plate. With the continued development of China’s power transmission industry, non-magnetic steel is widely used to replace low-magnetic austenitic stainless steel, demand is increasing, and domestic and foreign steel companies competing to develop. However, the manganese content of non-magnetic steel is as high as 25% and aluminum content is as high as 2%, which are 20 times and 200 times of conventional steel, respectively, with high smelting safety risks and high-quality control difficulties, and the conventional production process cannot guarantee stable production requirements.
In 2017, the Wire Rod Research Institute of JISCO and the rolling mill started to plan the development of the non-magnetic steel project. in 2018, industrial production started and the first furnace of non-magnetic steel was successfully produced, but the smelting time was more than five times the smelting time of conventional steel grades. For this reason, they decided to change the furnace and adopt a new process of non-electric furnace smelting. The smelting time of the new process was significantly shortened, and the alloy yield was up to more than 95%.
Due to the high manganese and aluminum content, domestic and foreign steel mills use die-casting to produce high manganese steel grades, which makes it difficult to guarantee the surface quality of ingots. JISCO insisted on continuous casting production from the very beginning, and the R&D team overcame multiple difficulties such as developing large columnar crystals in the two-phase area of the steel grade, large alloy ratio, low solidification speed, and difficulty in continuous casting and became the third company in the world after POSCO and TISCO to successfully continuously cast and roll non-magnetic steel.
At the beginning of 2020, all the properties of Jiu Steel’s non-magnetic steel were tested by several units, including the National Steel Materials Testing Center, Xinjiang Quality Supervision Bureau, Lanzhou University of Science and Technology, and Beijing University of Science and Technology, etc. All the properties of Jiu Steel’s non-magnetic steel met the standards. Meanwhile, the test results show that Jiu Steel’s original production process of high manganese non-magnetic steel 20Mn23AlV has reached the leading level in the industry.