Mechanical properties and microstructure of high toughness Fe-base filaments produced by glass-coated melt spinning

High toughness Fe_57.5Co₅Cr₁₅Mn₁₀Cu₂B₁₀Ti_0.5 filaments having a high tensile strength of 1740 M Pa and high elongation of 11.0% were produced by the method of glass-coated melt spinning. A noticeable feature of the stress-strain curves of the filament was that rapid hardening to a high stress-level of more than 1500 M Pa was reached in the first few per cent of tensile elongation. The filament was 14.5m diameter and micropolycrystalline with a grain size of 27 nm. The crystal structure of the filament was a mixture of bcc and fcc phases and the two phases were distributed homogeneously in the filament. The high toughness of the filament related to its micropolycrystalline structure and the uniformly mixed structure of bcc and fcc phases. After heat treatment at 573 K for 600 sec, the filament developed a higher toughness with a tensile strength of 2150 M Pa and an elongation of 12.0%.