Papers by Author: A.L. Rivas

Abstract: The present investigation evaluates the effect of static annealing variables on the grain structure and mechanical properties of a 0.04 %C-Al killed steel. The experimental variables selected were the heating rate and the initial heating temperature. The results showed that an increase in the initial heating temperature and heating rates inferior to 500°C and 100°C/h, respectively, do not have a major influence in the grain structure of the material. These annealing conditions lead to a full "pancake" type of microstructure of the recrystallized ferrite grain, and as consequence, the mechanical properties of the material are in the intervals required for deep drawing applications.

Abstract: The effect of heating rate and annealing time on the microstructure and texture of a commercial 0.04 %C steel, cold rolled up to 80 %, is studied. Samples have been isothermally annealed at various heating rates (12 °C/h, 20 °C/h, 40 °C/h and 650 °C/min) and then soaked at 700 °C for 15 hours. The microstructural evolution of the samples during the heating process and hold period has been followed by optical microscopy, scanning and transmission electron microscopy. The electron back-scattered diffraction technique is used to reveal the texture of the samples. Tensile tests and hardness measurements are correlated with the microstructural features. Results show that (a) recrystallization occurs between 600 and 650 °C; (b) a “pancake” structure develops during recrystallization at low heating rates without appreciable grain growth; (c) samples heated at 650 °C/min exhibit an equiaxed grain structure and significant grain growth; (d) only at low heating rates the material develops a strong {111} recrystallization texture, in ccordance with the high plastic anisotropy found by mechanical testing.