Texture and Formability of One-Step and Two-Step Cold-Rolled and Annealed Interstitial Free High-Strength Steel Sheets

Abstract

In the current experimental investigation, a comparative study has been carried out to understand the development of texture under different conditions, viz. controlled hot-rolled, one-step cold-rolled (CR) and annealed, and two-step cold-rolled and annealed conditions. Mechanical properties were determined and experimental formability limit diagrams (FLDs) were plotted after both one-step and two-step cold-rolled and annealed conditions. From the tabulated data, it was found that hot band texture of 85 to 90 pct deformation was strong and the main orientations were $\left( {112} \right)\left[ {1\bar{1}0} \right]$ and $\left( {332} \right)\left[ {\bar{1}\bar{1}3} \right].$ One-step cold rolling developed the strong and uniform α-fiber and γ-fiber at 80 pct cold reduction. The strong and uniform new γ-fiber was obtained at the one-step 80 pct CR annealed condition. In addition, the highest drawability was found at the one-step 80 pct CR annealed condition. In two-step cold rolling, orientation $\left( {223} \right)\left[ {1\bar{1}0} \right]$ was the main texture component along with extremely strong γ-fiber. Moreover, batch annealing of two-step cold-rolled steel sheets developed exceptionally strong and uniform γ-fiber, and all mechanical properties were enhanced significantly except yield strength. From FLDs, it is observed that the formability properties of interstitial free (IF) high-strength (HS) steel sheets were excellent at both one-step and two-step cold-rolled and annealed conditions. However, the two-step cold-rolling and annealing process was found to be superior to the one-step process. The data of this investigation may be used at the industrial level to design the entire processing of IF-HS steel sheets.