Microstructure and strength in ultrastrong cold-drawn medium carbon steel

Via traditional wire drawing, the medium carbon ferrite-pearlite (MCFP) steel wires can achieve ultrahigh strength beyond 4 GPa normally for high-carbon pearlitic wires, but have a 30–60% lower production cost. The microstructural evolution and mechanical properties of been investigated by means scanning electron microscopy, transmission microscopy tensile testing. increases from 750 MPa up to 4120 when drawing strain ε = 6.4, which represents highest reported so far – our knowledge with such low content. At strains (ε ≤ 1.95), proeutectoid ferrite forms dense dislocation walls (DDWs) via activities, including sliding, accumulation, interaction, tangling. With increase, reorientation DDWs direction coarse lamellae. Finally, deformed high is characterized lamellar morphology average spacing about 55 nm at 6.4. interlamellar pearlite thickness cementite decreases increases. density in lamellae increases, 7.8 × 1015 m−2 4.19. A higher 3.1 1016 be obtained 6.4 extrapolation TEM investigations. stress contributions flow are estimated based on quantified structural parameters. Based assumption that different strengthening mechanisms linearly additive general rule mixtures, good agreement between measured stresses has found large range stress. application mixture indicates importance quantitative characterization parameters strain.