Evolutions of microstructure and ferritic micro-orientation and texture in a pearlitic steel wire during cold drawing

Cold drawn high-carbon pearlitic steel wires have the highest strength of all mass-produced steel materials and are widely used in industry for a variety of applications, including cables for suspension bridges, steel cords for automobile tires and springs. At present the maximum tensile strength of high-carbon steel wires has already reached a value of 5.7 GPa. The properties of steel wires, including strength, fatigue properties and torsinal properties, are deeply affected by microstructure and ferritic micro-orientation and texture in the deformed pearlite. In this study, the evolutions of microstructure and ferritic micro-orientation and texture were investigated in a pearlitic steel wire during cld drawing using electron channel contrast (ECC) and electron backscatter diffraction (EBSD) techniques. The results show that there exist shear-bands (S-bands) in the deformed pearlite microstructure. Their appearance is related to the angle between cementite plates and the drawing axis: the larger the angle is, the more S-bands appear in the structure. The pearlite structure turns to the drawing direction and the angle between S-band and drawing axis decreases with the increase of strain. The S-bands in the deformed pearlite colony induce the rapid change of local orientation of ferrite, and make the pearlite colony subdivide into several areas by high angle boundaries of ferrite. The strog ≤110> fibre texture f ferrite parallel to the drawing direction forms with the increase of strain, but the intensity of ≤110> fibre texture of ferrite is inhomogeneous from the centre to surface in longitudinal section with the strongest in the centre and the weakest near the surface. ©.