The effect of scale microstructure on the pickling of hot‐rolled steel strip

Abstract

One of the problems in the production of narrow hot‐rolled mild steel strip is the formation, at the edges of the strip, of scale that can be extremely resistant to pickling; This extreme resistance to pickling of ‘hard edge scale’ sometimes requires repickling of a considerable percentage of coils with consequent loss of production and deterioration of surface finish. The paper considers in detail the correlation between the microstructure of scale on the strip and its pickling behaviour. It is shown that certain characteristics of the microstructure, peculiar to ‘hard edge scale’, i.e. increased thickness, the presence of a primary magnetite layer, greater degree of wüstite transformation and the nature and presence of haematite, can be suppressed to a greater or lesser degree by variations in the cooling cycle. It is considered that no single one of these structural differences between hard edge scale and that which is removed readily from the centre of the strip would, by itself, interfere with pickling, but when these characteristics occur together repickling is made necessary. The above observations and conclusions are supported by results obtained from pickling tests carried out in the laboratory on samples taken from a wide range of coils.

Citation

Tuck, C.W. (1969), "The effect of scale microstructure on the pickling of hot‐rolled steel strip", Anti-Corrosion Methods and Materials, Vol. 16 No. 11, pp. 22-27. https://doi.org/10.1108/eb005286