Comprehensive Observations and Interpretations in Al-Rich Interstitial-Free High-Strength Steel via Process-Induced Structure Evolution

Developing ND parallel to< 111 > fiber texture is vital for assessing the properties of interstitial-free high-strength steels utilized in the automotive industry. The present work deals with the microstructure and texture evolution in titanium-niobium-stabilized interstitial-free high-strength steels with varied aluminum content. Industrially hot-rolled steels with different aluminum content (0.045 and 0.12 wt.%) were cold-rolled (similar to 90%) and isothermally annealed at 650 and 750 degrees C for multiple time intervals. Texture studies showed a similarly weak hot band textures. After annealing, a stronger {111} recrystallization texture was observed in high-Al steel than in low-Al steel. High-Al steel depicted faster recrystallization than that of low-Al steel. In the early stages of recrystallization, a variation in the recrystallization behavior of the steels was observed. The presence of the strain-induced boundary migration at the beginning of annealing triggered recrystallization of 10011 <110 > grains and caused sluggish recrystallization of {111} < uvw > grains in low-Al steel. In contrast, the rapid recovery of {111} fiber grains hindered the effect of strain-induced boundary migration in high-Al steel. It resulted in faster recrystallization of {111} < uvw > and stronger {111} fiber texture. A higher annealing temperature and grain growth further strengthened the {111} fiber texture in both steels.