Microstructures and mechanical properties of fiber textures forming mesoscale structure of drawn fine high carbon steel wire

The crystal orientation of a drawn high carbon steel wire was analyzed through electron backscatter diffraction analysis under the assumption that the wire consists of a mesoscale structure characterized by the fiber texture. The microstructure forming the mesoscale structure and the mechanical properties depending on the mesoscale structure were explained by the results of transmission electron microscopy observation, measurement of the electrical resistivity, differential scanning calorimetry thermal analysis, and tensile testing. In the beginning of the wire drawing, the wire has only {100}<110>−{111}<110> (the primary fiber texture). Then, the wire has this orientation at the outer side and {110}<110>−{111}<110> (the secondary fiber texture) at the inner side. At a drawing strain larger than approximately 2.7, the subprimary fiber texture ({100}<110>−{111}<110>) is formed at the outer side and will occupy the volume of the wire. The results indicate that with the increase of the drawing strain, the lamellar spacing decreased, and the amount of lattice defects increased. The tensile strength, uniform elongation, and reduction of area were typically uniform in the radial direction of the wire. On the other hand, the wire with only the primary fiber texture had lamellae whose angle with respect to the drawing direction decreased during wire drawing, as well as a surface layer with low longitudinal ductility. The wire with the subprimary fiber texture contained decomposed cementite. The wire also had a large variation of reduction of area. Increasing the back stress ratio shifts the transition of the mesoscale structure to a lower drawing strain.