Regularities of Crystallographic Texture Formation in Austenitic Steel during Rolling and Tensile Testing

Abstract

AISI 304 steel samples cut from a forged rod were rolled at room temperature using longitudinal and cross schemes, after which they were subjected to various heat treatments with cooling from temperatures of the two-phase α′ + γ- and single-phase γ-regions to fix different phase compositions. The phase composition was studied, the volume fractions of austenite and α′-martensite, crystallographic texture, structure and substructure of two-phase steel were determined, uniaxial tension tests of rolled sheets in different directions were carried out to evaluate the anisotropy of mechanical properties. It was found that the occurrence of γ → α′ phase transformations during deformation significantly depended on the rolling scheme and conditions, and the amount of remaining austenite varied within 15–29%. The reverse α′ → γ phase transformation initiated by annealing in the single-phase γ-region leads in the case of longitudinal rolling to the multiplication of the γ-phase texture components and the appearance of an additional orientation {113}〈332〉, while in the cross scheme the texture of deformed austenite is preserved. Quenching in the two-phase region at 700°C does not lead to a fundamental change in the austenite texture but ensures the appearance of additional martensite components {110}〈001〉 and {112}〈111〉. The texture features affect the anisotropy of elastic properties and yield strengths: the anisotropy of the Young’s modulus of samples consisting entirely of austenite is higher (E_TD/E_RD = 1.67) compared to 1.25 for samples of quenched two-phase steel.