A Study of the Influence of Rolling Geometry Upon Texture and Drawability of Rimmed Steel Strip

Abstract

The influence of seven different rolling schedules upon R values and textures of cold rolled and of subsequently annealed rimmed steel strip has been studied. The effect of increasing the annealing time upon R value and texture was also examined. R value measured in a tensile test was related to the corresponding texture determined by inverse and (110) pole figures. The seven rolling schedules consisted of three constant roll gap schedules, in which roll gaps of 0.001 in/pass, 0.005 in/pass and 0.02 in/pass were kept constant during the cold rolling process. The other three rolling schedules involved constant geometry and were designed to maintain constant shear plane angles of 55°, 45° and 35° to the strip surface, from one pass to the next. The seventh rolling schedule represented a pendulum mill schedule. Measurements of R values revealed that R values of the cold rolled materials were very low but improved after annealing. The longer the annealing time the more the R values became dependent upon the rolling schedules and total rolling reductions. However, after 6 hrs annealing, R values of strips previously cold rolled ‘using constant roll gap schedules increased with the magnitude of the roll gap and with the total rolling reduction to a maximum and thereafter decreased. On the other hand, R values of corresponding strips cold rolled using controlled geometry schedules increased with decreasing the shear plane angle and remained constant when the total rolling reduction was increased. R values of equivalent strips cold rolled by the pendulum rolling schedule decreased with increasing the total rolling reductions. The cold rolling textures observed were typical of b.c.c. iron with <110> direction parallel to the rolling direction and {111} planes parallel to the rolling plane. For a given total rolling reduction, intensities of the {100} and {111} planes were dependent upon the rolling schedules and total rolling reduction. Rolling with constant roll gap was associated with a decrease in the {100} intensity and an increase in the {111} intensity with increasing the total rolling reduction up to certain reduction then increased and decreased respectively. The total rolling reduction corresponding to the minimum {100} and maximum {111} intensities increased with increasing the magnitude of roll gap. As a result of rolling with constant geometry schedules, intensity of the {100} and {111} planes remained constant with increasing the rolling reduction but their intensities increased and decreased respectively with increasing the shear plane angle. When rolling on the pendulum mill, intensities of the {100} and {111} planes increased and decreased respectively with increasing the total rolling reduction. Annealing for 0.5 hr was associated with a significant decrease in the {100} and {111} intensities. Increasing the annealing time resulted in a further decrease in the {100} intensity and an increase in the {111} intensity. The relative intensities of the {100} and {111} planes varied with the rolling schedules and with increasing the total rolling reduction in the same manner as for the cold rolled material already described.