Effect of the High-Temperature-Coiling on the Properties of Continuously Annealed Product

Abstract

In contrast to the established processing principle for the batch annealed cold rolled sheet gauge product, where the hot strip is coiled at a temperature around 560°C, coiling at a higher temperature near 700°C is desirable when the cold rolled strip is processed through the continuous annealing line.
The high temperature coiling is beneficial both to the formation of faborable recrystallization texture and the grain growth at the continuous annealing stage. These beneficial effects owe to the microstructure of the hot band, which is characterized by the coarsened carbides and a larger ferrite grain size. Of these, the former is responsible for both the texture formation and the larger ferrite grains.
The coagulated carbides serve to make the situation where recrystallization commences with the solute carbon content far less than the solution limit, leading to the formation of the {111} rich texture.
The coagulation of carbides is beneficial also to the grain growth, since the spacing of the particles are several times larger than the recrystallized ferrite grain diameter and the inhibition of grain boundary migration is greatly reduced.