Strip Cooling Optimization by Means of Fully Coupled Thermo-Mechanical-Metallurgical 3D Model J. H. Bianchi 1 , L. Langellotto 1 , J. Díaz Alvarez 2 1 Centro Sviluppo Materiali S.p.A., 2 Arcelor Mittal España S.A. Abstract: Advanced High Strength Steels (AHSS) are the fastest growing segment of strip products due to their high demand in the automotive industry. Because they represents valid alternative to the use of expensive ferroalloys, steel producers are pushed to improve the processing routes and guarantee uniform properties conforming to specific targets. During the cooling phase on the Run Out Table (ROT), thermal and phase transformation inhomogeneities throughout the strip could lead to some sectors of this not conforming to target mechanical properties. Moreover, the differential shrinkage between neighboring fibers might induce plastic deformation leading to permanent loss of flatness. CSM metallurgical module microView TM has been fully coupled in Abaqus/Standard Thermo- Mechanical analysis and used in 3D modeling under generalized cooling conditions. First, it was applied to simulate rolling experiments done at CSM pilot mill using different cooling rates; the predicted volume fraction of constituent phases were compared against Metallographic measurements with good agreement. Secondly, the model was applied to an Arcelor Mittal España SA industrial line configuration and a sensitivity analysis was carried out to assess the effect of different cooling rates at the upper and lower face of the strip and finishing mill conditions (Temperature and Austenite grain size) on both breakdown of constituent phases and flatness. The model can be effectively used to optimize industrial parameters to guarantee dimensional/microstructure uniformity and absence of flatness. Moreover, an “early-quick” strategy that involves finishing water cooling and coiling the strip earlier were also examined and industrial practice modified accordingly to the predictions, with improvements in the strip quality Keywords: AHSS, Multiphase Steels, High Strength Steels, Hot Rolled Strip, Hot Rolling Technology, ROT, Run Out Table, Cooling bed, Coiling, Strip Flatness, Microstructural Coupling, Austenite Decomposition, Austenite Evolution, SRX, MDRX,DRX, Grain Size, Multiphase Properties. 1. Introduction The industrial production of modern microalloyed Advanced High Strength Steels (AHSS) strips such as Partially Bainitic, Dual Phase, Multi-Phase or TRIP, poses stringent requirements not only to rolling technology but also on the development and control of key properties during the accelerated cooling that follows (Sellger, 2003; Ibrahim, 2007; Bhattacharya, 2010; De Moor, 2010; Li, 2010; Barbero, 2012). These AHSS strips are produced from as-cast stocks heavily reduced to typical final thickness of 3 to 5 mm and width 1.2-1.50 m by a sequence of several rolling passes in Austenite state, followed by controlled cooling at the Run Out Table (ROT) and coiling of the strip (Figure 1). Austenite decomposes at the ROT in Ferrite and