Influence of Strain Path Changes on Microstructure Inhomogeneity and Mechanical Behavior of Wire Drawing Products

Abstract

Cold drawn low carbon steel wires are widely used in several engineering applications where a proper combination of strength and ductility is of the paramount importance. In the present paper, the multi-pass angular accumulative drawing (AAD) is proposed as a new forming process where the high strain accumulation is used as a way to achieve much higher microstructure refinement level compared to the conventional wire drawing process. This process is characterized by a complex strain path history, being an effect of wire diameter reduction, bending, tension and torsion, what directly affects the microstructure changes in the final product. This process also evolves high inhomogeneity of microstructure, that if properly controlled, can lead to further properties improvement - what can be especially beneficial for alloys that are not characterized by complex compositions. In the present paper, special emphasis is given on the inhomogeneity of both deformation and microstructure and resulted mechanical properties. After drawing and annealing (at 500oC) mechanical properties measurements and microstructure analysis on the longitudinal sections of the wires were performed to assess the differences existing with respect to the conventional wire drawing process.