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1.
Reducing scrap in long rolled round steel bars using Genetic Programming after ultrasonic testing
Miha Kovačič, Anže Zupanc, Uroš Župerl, Miran Brezočnik, 2024, izvirni znanstveni članek

Opis: At Štore Steel Ltd., continuously cast billets (180 mm × 180 mm) are reheated and rolled after cooling to room temperature. Hot-rolled bars are controlled as they cool to room temperature in specially designed cooling chambers, minimizing residual stresses and the development of pre-existing surface and internal defects. The bar ends can be additionally covered with insulating material. The cooled, rolled bars undergo examination using automated control lines to detect surface and internal defects, which primarily originate from the casting process. Internal defects are identified using ultrasonic testing. Between January 2022 and June 2023, 1550.0 tons of 61SiCr7 rolled bars, with diameters ranging from 53 mm to 72 mm and lengths from 7010 mm to 7955 mm, were examined using ultrasonic testing. The scrap was 109.6 tons (7.07 %). After collecting data on chemical composition (C, Si, Mn, Cr, Mo, Ni content), the casting process (casting temperature, cooling water pressure and flow in the first, second, and third zones of secondary cooling, as well as the temperature difference between input and output mould cooling water), and rolled bar geometry (diameter, length), scrap modelling after ultrasonic testing was carried using genetic programming. The genetic programming model suggested reducing the length of the rolled bar. Due to length multiplication, it was possible to reduce the rolled bar length from the initial lengths of 7010-7955 mm to the current lengths of 4558-6720 mm in June 2023. Based on this adjustment, a new production of rolled bars was established. By August 2024, 1251.9 tons of 61SiCr7 rolled bars were produced with the mentioned length adjustments. These rolled bars were subsequently examined using ultrasonic testing. The scrap was reduced by nearly 14 times, amounting to only 8.1 tons (0.64 %).
Ključne besede: steel industry, rolling, long bars, ultrasonic testing, scarp, defects, modelling, genetic programming
Objavljeno v DKUM: 27.08.2025; Ogledov: 0; Prenosov: 3
.pdf Celotno besedilo (681,48 KB)
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2.
Alliance networks : the case of multinational corporations
Władzimierz Sroka, 2010, izvirni znanstveni članek

Opis: The article deals with the problems of cooperation in network organizations. The structure of the text is divided into a couple of parts. Firstly, the increasing importance of alliance networks is described. Secondly, the concept of alliance networks as well as the essence of multinational corporations are presented. Beside theoretical deliberations, two practical cases are presented in the text too. First case relates to the Toyota keiretsu and the second one describes the network organization of the largest steel manufacturer in the world, i.e. ArcelorMittal Group. Last part of the text is the comparative analysis of the multinational corporations network vs. networks of small and medium size companies. The similarities as well as differences between both forms were presented. The article is based on the latest world literature devoted to the cooperative strategies as well as the practical business experience of the author from the work in Arcelor Mittal Poland and polish machine industry.
Ključne besede: cooperation, alliance network, multinational corporation, keiretsu group, steel industry
Objavljeno v DKUM: 10.07.2015; Ogledov: 1040; Prenosov: 176
.pdf Celotno besedilo (307,21 KB)
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