Industrial Research in Thicker Heavy Plates (70-80 mm) HSLA Steel Micro-Alloyed with Mo-NbTi Thermo-Mechanical Control Process in ArcelorMittal Galati
Abstract
Thermomechanical rolling (TMR or TMCP) is a special rolling process resulting in an extremely high-strength, fine-grained substructure which simultaneously offers very good toughness and cold formability. TM products have much lower carbon content and consequently are much less susceptible to cold cracks during welding. In ArcelorMittal Galati the challenge was to increase for structural steel the feasibility from 50 up to 80 mm and targeted plate thickness without ACC mode. Slabs thickness produced in AMG with maximum 250 mm thickness corresponding to almost the maximum ratio of 3:1 between slabs and targeted plate thickness according to the EN 10025/4/2004. TM rolled steels performed in industrial trial presented in this paper were performed in Heavy Plate Mill no 2 in ArcelorMittal Galați using computer process SIROLL assisted by AGC system. The main goal of this experimental rolling is to provide a concise and complete overview of the rolling process with higher amount of deformation below Tnr (non-recrystallisation temperature) and close to Ar3 in austenite region, and to address the potential to optimize it.
References
[2]. Prabal Gumar Ray, Ratan Indu Gangulay, Ashok Kumar Panda, Determination of Recrystallization stop temperature (TR) of an HSLA steel, Journal of Steel and related Materials - published in 2004.
[3]. Jian Fang, Experimental study on the relationship between impact fracture properties and titanium addition for HSLA steels, Technical Center, Baoshan Iron and Steel Co., Ltd., Shanghai 201900, China.
[4]. ***, http://galati.arcelormittal.com/about-s/arcelormittalprofile.
[5]. Hashimoto Shunichi, et al., Effects of Nb and Mo addition to 0.2% C-1.5% Si-1.5% Mn steel on mechanical properties of hot rolled TRIP-aided steel sheets, ISIJ, p. 1590-1598, 2004.
[6]. Craven A. J., He K., Garvie L. A., Baker T. N., Complex heterogeneous precipitation in titanium-niobium microalloyed Alkilled HSLA steels-I. (Ti, Nb) (C, N) particles. Acta Materialia, 48 (15), p. 3857-68, 25.09.2000.
[7]. Kunishige K., Nagao N., Strengthening and toughening of hot-direct-rolled steels by addition of a small amount of titanium, ISIJ International, 29 (11), p. 940-946, 1989.
[8]. Costel Durduc-Roibu, Elena Drugescu, Effect of intercritical hot rolling deformation on steel grade for welded pipes with lean chemistry, The annals of “Dunarea de Jos” University of Galati, Fascicle IX, Metallurgy and Materials Science, p. 171-178, 2012.
