New Sheet Steel Production Processes

Published: Wednesday, 09 February 2022 04:40

Researchers from NMSTU are working on developing production processes to make steel that would combine high strength and high plasticity, while no heat treatment is involved.

The study is conducted on the new asymmetric rolling mill, which can roll steel workpieces reaching a 75 to 90% reduction in one pass. The mill has been in use at Zhilyaev Mechanics of Gradient Nanomaterials Laboratory for less than a year, and over that period researchers were able to increase metal plasticity due to optimum roll velocity errors that were found. For example, if aluminium alloy D16 fractured in the common cold rolling operation when the reduction reached 43%, in the asymmetric rolling operation it was reduced by 90% gaining a double increase in plasticity.

“Another peculiar property that we witnessed in the course of the study is that the process can start as a cold rolling operation, with no heat applied, and at its final stage it can turn into a hot rolling operation. This could be of interest with regard to copper alloys as the rate of phase transformations in them is quite high. A workpiece is heated to the required temperature at entry to the deformation zone and is immediately cooled down to 200-300 degrees. This process is referred to as air quenching. As a result, desired properties are obtained with no heat or further heat treatment applied,” – explains deputy head of the Laboratory Alexander Pesin.

According to the researchers, cold-rolled sheets produced by asymmetric rolling have high strength and high plasticity at the same time, and they can find applications in automobile and aerospace industries. This new type of steel will help make any structure lighter and strong at the same time.

“What we achieve in the asymmetric rolling mill is dynamic recrystallization with no heat treatment applied, which is due to high shear strains and the heat generated as a result. This is of importance when one aims to develop new rolling processes for various steels. At the moment we are working on proposals for steel producers (including MMK) to adopt the processes developed by our laboratory. For example, the production process for making steel bands from a number of steel grades involves up to four rolling-annealing cycles. If we can get rid of at least one cycle due to the use of asymmetric rolling, this will save a lot of cost,” – adds Alexander Pesin.

NMSTU’s Zhilyaev Laboratory has partners from multiple Russian and foreign universities and institutes. They include Central South University in Changsha, China; Indian Institute of Information Technology, Design and Manufacturing in Jabalpur, India; Polytechnic University of Catalonia in Barcelona, Spain, and others. New heat-resistant aluminium alloy that can withstand temperatures up to 400 °C developed by MISiS is currently being tested in the asymmetric rolling mill at NMSTU.

“In our research we engage high school students from NMSTU’s Project School. At this time, they are looking at binary alloys. Their task is to weld two workpieces together in a rolling operation and understand how various parameters effect the properties of the resultant laminar product. They are to present the obtained results at the international science conference that will take place at NMSTU this April. This is our way to engage young people in research activities,” – says Mr. Pesin.

Researchers from the Laboratory, together with their colleagues from China and India, have so far obtained 8 Eurasian patents. Not only do they develop processes from steel melting to obtaining desired properties, but they can also produce small pilot batches of specific materials.

As a reminder, the study was carried out under Decree no.220 dated April 9, 2010 by the Government of the Russian Federation, and it was funded by the Russian Science Foundation and the Russian Foundation for Basic Research.