Texture Formation in Flow Formed Ferritic Steel Tubes and the Influence of the Process Parameters

Abstract

The crystallographic textures of flow formed parts are of great scientific interest as they result from a complex deformation mode that comprises strain components in the axial and hoop directions. In general they resemble those of the rolling type but with slight differences. The present paper analyses the effects of certain process parameters, such as roller contact angle, feed rate, and preform hardness, since these are crucial in defining the forces acting in each principal direction of the component. Additionally, the development of a texture gradient through the wall thickness is also discussed. Texture predictions from a crystal plasticity finite-element model were also employed to support the experimental data and interpret the deformation mechanisms. Finally, the diverse nature of the flow formed textures is verified by annealing treatments at 700°C, which yields the typical gamma-fibre encountered in rolled ferritic steels upon recrystallisation in conjunction with the strengthening of the (113)[1-10] component.

Forming of metastable austenitic stainless steel tubes with axially graded martensite content by flow-forming

“…The ratio of these components depends mainly on the rollers' attack angle, transition radius and exit angle [11]. Among others, Tsivoulas et al [12] and Jahazi and Ebrahimi [11] have investigated the dependence of the rollers' workpiece contact area and the resulting material flow. Their investigations indicate that the ratio of the axial to the radial material flow is determined by the ratio of the axial to the radial contact area of the roller and the workpiece.…”