Estabilidad de la austenita retenida bajo condiciones de deformación en aceros multifásicos con bainita nanoestructurada

AUTOR(ES)
FONTE

Matéria (Rio J.)

DATA DE PUBLICAÇÃO

19/07/2018

RESUMO

ABSTRACT A steel with nominal composition 0.25C, 1.9Si, 0.63Mn, 1.5Cr was manufactured using an induction furnace. The as-cast alloy was homogenized and the temperatures of austenite start (AC1) and finish (AC3) during heating were determined by dilatometric analyses. Two intercritical austenitization temperatures were selected, which were used to perform partial austenization followed by isothermal treatment in a salth bath. The heat treated steel was characterized by optical microscopy, scanning electron microscopy, and x-ray diffraction. The microstructures contained proeutectoid ferrite, martensite, bainite and nanometric retained austenite. These steels were subjected to plastic deformation by cold rolling to evaluate the stability of the retained austenite under strain. It was found that the fraction of retained austenite increased and its stability under deformation conditions decreased as the intercritical austenitized temperature diminished. The combination of intercritical austenization followed by low temperature austempering on an alloy with suitable chemical composition allowed to obtain steels that combine the microstructures of TRIP and Nanobain steels.

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