Processing of Low-Carbon Deep-Drawing Steel with High Plastic Anisotropy Using Two-Stage Batch Annealing Cycle

Abstract

Anisotropy in texture determines capacity of the steel to achieve maximum plastic flow in the plane of the sheet and maximum resistance to flow in a direction perpendicular to the sheet. Present work has been carried out to explore the potential of maximizing plastic anisotropy (rm) value in extra deep-drawing steel. Industrial heat was made with low carbon (0.03 wt.%), low manganese (0.15 wt.%), and low sulfur (0.007 wt.%) levels. Continuously cast slabs were hot-rolled and then cold-rolled to 1 mm thickness. The cold-rolled sheets were subsequently subjected to annealing in an annealing simulator furnace adopting specially designed two-stage batch annealing cycle. In batch-annealed steel samples, grains were found to be recrystallized and had undergone grain growth preferentially along the longitudinal direction with strong gamma fiber, comparable to that of Interstitial Free steel. Excellent combination of strength and forming properties, in terms of yield strength 190 MPa, ultimate tensile strength 290 MPa, and total elongation 45%, YS/UTS: − 0.66 with very high plastic anisotropy (rm): 2.45, could be achieved. Properties achieved have been correlated with the alloy chemistry, processing path history, percentage reduction, two-stage batch annealing cycle and the resultant grain size, microstructure and texture.