A new type of steel was developed by a team of scientists in China that has stretchable and durable key attributes. This could potentially overcome a tough challenge in steelmaking especially that strength and ductility are usually mutually exclusive.
Hydrogen direct reduced iron pellets are pictured at the HYBRIT pilot facility (a collaboration project between steelmaker SSAB, state-owned utility Vattenfall and mining company LKAB) in Luleå, northern Sweden, on August 27, 2021. - In a gleaming new building in the northern Swedish town of Lulea, steelmaker SSAB is using a new manufacturing method that could revolutionise the highly-polluting industry by eliminating nearly all its CO2 emissions. (Photo by Jonathan NACKSTRAND / AFP) (Photo by JONATHAN NACKSTRAND/AFP via Getty Images)
JONATHAN NACKSTRAND/AFP via Getty Images
(Photo : JONATHAN NACKSTRAND/AFP via Getty Images) Hydrogen direct reduced iron pellets are pictured at the HYBRIT pilot facility (a collaboration project between steelmaker SSAB, state-owned utility Vattenfall and mining company LKAB) in Luleå, northern Sweden, on August 27, 2021.
The demand for mechanically strong and ductile steel materials has been increasing day by day in several sectors and different industries like transportation, infrastructure, etc. While unifying both features in one material may be challenging, a group of scientists developed this kind of steel.
Scientists from Northeastern University in Shenyang, Shenyang National Laboratory for Materials Science, Jiangyin Xingcheng Special Steel Works in Eastern China, including Max Planck Institute for Iron Research in Germany, were the ones who developed plain medium manganese steel.
According to the South China Morning Post's report, this piece of steel is the same size as a fingernail that can bear the weight of a 2-tonne car without snapping. Additionally, the ductile metal can be stretched by 18 to 25 percent from its original form.
The study added that through the material, several inventions can be implemented in the vehicle, aerospace, and machinery sectors as they can be formed into complex shapes and absorb high energy from the impact of the collision.
Making the Steel
As per the released findings in the peer-reviewed journal Science, Ductile 2-GPa steels with hierarchical substructure required the scientists to use a combination of multiple transversal forging, cryogenic treatment, and tempering steps to produce a steel with both characteristics.
Scientists combine melted raw alloyed material at 650 to 800 degrees Celsius or 1,200 to 1,470 Fahrenheit. The special structure will be formed as the steel cools in the air. After this, they used liquid nitrogen with a temperature of minus 196 degrees Celsius to cool it down further. To improve its stability, the steel will be heated again at 300 degrees Celsius.
Northeastern University's State Key Laboratory of Rolling and Automation Postdoctoral Researcher and the lead author of the study Li Yunjie stated that the process is much simpler than on what they used to make conventional ultra high-strength steels that are rolled to form thin plates or sheets.
He described the produced 2 gigapascal strength steel as "almost the highest tensile strength in steels."
Aside from its characteristics, Li stated that this manufacturing method could reduce the costs of production to a tonne of steel by $75 or 510 yuan. This would also cut carbon emissions by more than 100 kg of coal equivalent per tonne.
"There is already a large-scale ship shaft with a tonnage scale based on the forging. Our process is consistent with its preparation with only a few adjustments in some process parameters," he added.
