Abstract:
This article presents the effects of different overaging temperatures adopted in continuous annealing line, on the microstructure and mechanical properties of HSLA500 steel. Four processing conditions were carried out, with variation in carbon with values of 0,06% and 0,08%, and overaging temperature, with values of 400°C and 420°C. The specimens produced, from sample obtained after industrial processing were characterized by tensile tests, metallographic analysis, chemical composition analysis, volumetric fraction analysis and particle size. The results of tensile strenght and yield strenght underwent analysis of variance (ANOVA). The results showed that the material submitted to a low overaging temperature presented a higher tensile strenght and a smaller volumetric fraction of cementite, and the opposite occurred for those submitted to a high temperature, for both percentages of carbon. In addition, particle size analysis showed cementite with smaller diameters in materials applied at lower temperature conditions and larger particle diameters for higher overaging temperatures. This indicates that the strength increase occurs due to cementite coalescing at lower overaging temperatures, resulting in precipitate refinement and dislocation movement blockage due to particles anchoring to the steel microstructure.