Microstructure and Crystallographic Texture Development of Microalloyed Twinning Induced Plasticity (TWIP) Steels Under
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Microstructure and Crystallographic Texture Development of Microalloyed Twinning Induced Plasticity (TWIP) Steels Under Uniaxial Hot-Tensile Conditions A.E. Salas-Reyes1, I. Mejía1 and J.M. Cabrera2,3 1 Instituto de Investigaciones Metalúrgicas, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Mich., 58066, México. 2 Departament de Ciència dels Materials i Enginyeria Metal·lúrgica, ETSEIB – Universitat Politècnica de Catalunya. Av. Diagonal 647, 08028 – Barcelona, Spain. 3 Fundació CTM Centre Tecnològic, Plaça de la Ciència, 2, 08243 – Manresa, Spain. ABSTRACT Nowadays, there are limited referenced data on the hot deformation of twinning induced plasticity (TWIP) steels, particularly on the crystallographic preferred orientation (crystallographic texture). It is well know that texture is one of the most important factors affecting sheet metal forming performance. The aim of this research work is to determine the influence of microalloying elements on the microstructure and texture of high-Mn austenitic TWIP steels deformed under uniaxial hot-tensile conditions. For this purpose, one nonmicroalloyed and other single microalloyed with Ti, V and Mo TWIP steels were melted in an induction furnace and cast into metal and sand molds. Samples with average austenitic grain size between 400 and 2000 μm were deformed in the temperature range between 800 and 900 °C at a constant true strain rate of 10-3 s-1. The evolution of the microstructure and texture near to the fracture tip were characterized using electron back-scattering diffraction (EBSD) technique. The results show that the TWIP steels microalloyed with V and Mo and the non-microalloyed one, solidified in metal mold, exhibit dynamically recrystallized grains oriented in the [012] preferential direction, which was corroborated by local misorientation measurements, indicating low dislocation density. On the other hand, most TWIP steels solidified in sand molds do not show dynamically recrystallized grains, having the largest austenitic grains oriented in the [001]/[101] preferred directions. In general, weak textural Cube {001} combined with fiber, namely γ-fiber, spread from E {111} to Y {111} as major texture components were detected. INTRODUCTION Among the recently developed steels, high-Mn austenitic twinning induced plasticity (TWIP) steels with low-to-medium stacking fault energy has received extensive attention because of its high strength and excellent ductility [1,2]. The stacking fault energy depends mainly on the chemical composition and temperature [3,4] and it is definitely a parameter that greatly influences the work hardening rate of the austenitic steels since it controls the deformation mechanism, i.e., dislocation glide and twinning [5]. However, under hot working conditions, the steels undergo significant microstructural changes as a result of various physical phenomena. First, with the increasing of deformation temperature, dislocation glide becomes dominant while twinning is gradually suppressed. And second, dynamic softening by both reco
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