AVALIAÇÃO DO AMACIAMENTO ESTÁTICO A QUENTE E A MORNO DE UM AÇO SILICIOSO

Abstract

Double hit compression tests were performed on an ultra low carbon Si-Al alloyed steel. The true strain in both deformation steps was kept constant (0.2), while varying the strain rate (1 s -1 , 10 s -1 and 30 s -1 ), the temperature (1,050°C-austenite phase, 950°C-intercritical region and 850°C-ferritic phase) and the interpass time (0.5; 1; 5 and 50 s). The temperatures used are within the industrial range applied in the finishing rolling for this steel. The analysis of the flow curves obtained allowed the evaluation of the static softening characteristics of the steel. It was shown that the steel has a similar softening condition between passes at the three temperatures studied, with the softening fraction increasing with the increasing time and strain rate. The characteristics of the softening curves and microstructural features indicate that at the two higher temperatures (austenite phase and upper part of the intercritical region) the softening process is governed by recrystallization, with the nucleation and growth of subgrains. At the lower temperature, however, the softening is mainly due to strain induced boundary movement (SIBM) and recovery.