Determination of residual stress and critical rolling temperatures in a microalloyed steel with low carbon and niobium contents

摘要

Using torsion tests, residual stress (DELTA sigma) and critical rolling temperatures (T_(nr), A-(r3), A_(r1)) have been determined for a low Nb content microalloyed steel by means of simulation of rolling cycles and subsequent representation of mean flow stress versus the inverse of the temperature. The above magnitudes were determined as a function of interpass time for two strains applied in each pass (0.20, 0.35), respectively. among the results found, it is notable that DELTA sigma decreases with longer interpass times until it reaches zero, and is greater the smaller the strain applied. With regard to the cooling transformation temperatures A_(r3) and A_(r1), these were found to be practically independent of the interpass time and were higher for smaller applied strains. Temperatures A_(r3) and A_(r1) were also determined by dilatometry, and comparison of these values showed that both methods yield similar results, except in the value of A_(r1).