Determination of the degree of recrystallization of a microalloyed HSLA steel by using metallographic methods

On the one hand, this work aims at describing the grain elongation of compressed samples of a microalloyed high-strength steel using appropriate parameters. On the other hand, the degree of recrystallization is to be determined based on the samples' grain elongation. For this purpose, single-hit compression tests were performed with varying test parameter settings using a deformation dilatometer to generate samples characterized by various degrees of recrystallization. Three parameters were chosen to describe the grain elongation. It was found that the parameter defining the ratio length/ width of the original grain provides the highest sensitivity regarding changes in the grain elongation. Aiming at determining the degree of recrystallization, a critical grain elongation threshold value was determined below which it is assumed that a grain is recrystallized. The results show that choosing the right threshold value allows an automated determination of the degree of recrystallization of a microalloyed high-strength steel in the light microscope.