The Effect of Heating Rate on Texture and Formability of Ti-Nb Stabilized Ferritic Stainless Steel

Abstract

Typical applications of ferritic stainless steels require good formability of the material that is highly dependent on the processing route. In this study, the effects of the heating rate and peak heating temperature on the texture and deep drawability (R-value) of a 78% cold rolled, stabilized 18Cr (AISI 441) ferritic stainless steel were studied. Pieces of cold rolled sheet were heated in a Gleeble 3800 simulator at the heating rates of 25 °C/s and 500 °C/s to various temperatures up to 1150 °C for 10 s holding before cooling at a rate of 35 °C/s. Microstructures were characterized and the texture of the annealed samples determined by the electron backscatter diffraction method. It was established that the high heating rate of 500 °C/s promotes the nucleation of grains with the near {111}<uvw> orientations during the early state of the recrystallization. The maximum texture intensities were found at {554}<225>. The more effective nucleation of these grains resulted in a finer grain size and an increased intensity of the gamma-fibre texture which led to enhanced R-values. At high peak temperatures, the intense grain growth took place.