Effects of Rolling Parameters on Texture and Formability of High Strength Ultra-Low Carbon BH Steel

Abstract

The effects of hot rolling and cold rolling parameters on texture and r (plastic strain ratio) value of high strength ultra low carbon bake hardening (ULC-BH) steels are studied with orientation distribution function (ODF) structural analysis method. After hot rolling, the high strength ULC-BH steel sheet has weak γ-fiber with uniform orientation distributions, and weak γ-fiber, of which {445}>110< component forms a high intensity peak at coiling temperature of 750 °C. After cold rolling, both {111}>110<−{111}>112< intensity on the γ-fiber and {111}−{112} >110< intensity on the α-fiber enhanced. As a result of substitutional solute elements Mn and P being added to the steel, strong {112}>110< deformation texture component is observed on γ-fiber, especially at 80% cold rolling reduction, and this leads to the strong {111}>112< recrystallization texture after annealing. The increase of cold rolling reduction shifts the maximum intensity on the γ-fiber from {111}>112< to {111}>113<. After annealing, a very strong γ-fiber is obtained, with intensity peak at {111}>112< component when cold rolling reduction reaches 80%. Increasing coiling temperature and cold rolling reduction improve γ-fiber intensity and r value, resulting in good deep drawability.