Influence of rolling variables on texture development and distribution in rimmed steel strip

Abstract

The influence of variation in rolling draught per pass under both dry and lubricated conditions on the texture of cold-rolled and of subsequently annealed rimmed steel strip has been studied in detail and the observations related to the strain ratio R0 value of the finally annealed strip. For any given total reduction the mid-plane texture was independent of the magnitude of the draught and was typical of that generally reported for iron, namely two partial <110>RD or {111}RP fibre textures. The main difference in texture was observed in the surface layer. Rolling with a light draught of 0·025 mm with either dry or lubricated rolls developed a predominantly <110)RD texture in the surface layer, Type I, which changed progressively towards the common medial plane texture. With draughts of 0·500 mm, again dry or with lubrication, the {111}RP fibre texture was dominant at the surface, Type III, which increased rapidly in relative intensity immediately beneath the surface to a uniform level throughout the remaining thickness. An intermediate state, Type II, was developed with a draught of 0·125 mm. Yet another surface texture, Type IV, was developed after a reduction in thickness of 88% using the heaviest possible draughts and dry magnesia-dusted rolls, which could be described as a {110}<112> rolling texture. The surface texture and through-thickness variations were somewhat reduced in intensity on annealing but unchanged in character. The strain ratio R0 value offinal annealed strip increased with total cold reduction and with magnitude of rolling draught to higher maximum values, that is in the order of Type I, Type II, and Type III texture development, and the R0 values could be correlated with corresponding {111}RP/{100}RP relative intensities. Heavy draught and reduction with dry, magnesia-dusted rolls results in Type IV texture and disastrously low Ro values. Since the experimental work was carried out on industrial hot-rolled stock the conclusions should be relevant to industrial practice.